Hinson v. Cont'l Tire The Ams. ( 2019 )


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  •                IN THE COURT OF APPEALS OF NORTH CAROLINA
    No. COA18-770
    Filed: 3 September 2019
    N.C. Industrial Commission, I.C. No. 240941
    GAIL CANUP HINSON, Executrix of the ESTATE OF WALTER DUNBAR HINSON,
    Deceased-Employee, Plaintiff-Appellant,
    v.
    CONTINENTAL TIRE THE AMERICAS, SELF-INSURED, Employer-Defendant-
    Appellee.
    PART OF THE CONTINENTAL TIRE THE AMERICAS CONSOLIDATED
    ASBESTOS MATTERS.
    Appeal by Plaintiff from opinion and award entered 25 January 2018 by the
    North Carolina Industrial Commission. Heard in the Court of Appeals 12 March
    2019.
    Wallace and Graham, PA, by Edward L. Pauley, for Plaintiff-Appellant.
    Fox Rothschild LLP, by Jeri L. Whitfield and Lisa K. Shortt, for Defendant-
    Appellee.
    McGEE, Chief Judge.
    This appeal is companion to four additional appeals, COA18-766, COA18-767,
    COA18-768, and COA18-769 (all five together, the “bellwether cases”), consolidated
    for hearing by order of this Court entered 8 June 2018. The four companion appeals
    will be decided by opinions filed concurrently with this opinion.
    I. Procedural History
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    Decedent Walter Dunbar Hinson (“Plaintiff Hinson”) worked for Continental
    Tire the Americas (“Defendant”) at Defendant’s tire factory (the “factory”) in
    Charlotte from 1967 until 1999.1 This case and the other bellwether cases involve
    workers’ compensation claims based on allegations that Plaintiff Hinson, along with
    the additional four plaintiffs2 in the bellwether cases (“Bellwether Plaintiffs”), were
    exposed to levels of harmful airborne asbestos sufficient to cause asbestos-related
    diseases, including asbestosis.3 The bellwether cases constitute a small percentage
    of a much larger number of related claims that were consolidated by the Industrial
    Commission (the “consolidated cases”).4 Determination of the bellwether cases will
    impact not only the Bellwether Plaintiffs, but also the remaining plaintiffs from the
    consolidated cases (together with the Bellwether Plaintiffs, “Plaintiffs” or
    “Consolidated Plaintiffs”). The Full Commission (the “Commission”) explained the
    unique procedure that was adopted to handle the large volume of consolidated cases
    in five opinions and awards, entered on 25 January 2018, that decided the bellwether
    cases:
    This case is part of a large group of cases (currently
    numbering 144) alleging occupational exposure to asbestos
    at [the] factory. The large group of [P]laintiffs contends
    1 The factory was initially operated under the General Tire name.
    2 Douglas M. Epps, Bobby James Newell, Frank Lee Welch, and Charles Edward Wilson.
    3 Plaintiff Hinson filed a Form 18B with the Industrial Commission, completed 23 May 2002,
    alleging he had developed asbestosis as a result of exposure to asbestos while an employee at the
    factory.
    4 The Commission’s 25 January 2018 opinion and award states that there were “currently” 144
    consolidated cases. However, the number of consolidated cases has fluctuated. Both Plaintiffs and
    Defendant moved to consolidate these cases.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    that they developed asbestos-related disease, primarily
    asbestosis, caused by exposure to asbestos at the
    . . . factory[.] Defendant denied that the diagnoses of
    asbestosis were valid, and also denied that any employee
    could develop an asbestos-related disease as a result of
    employment with [D]efendant because there was
    insufficient exposure to asbestos in [the] factory.
    [The consolidated cases] were postured so that there would
    be an “initial six” cases to be tried as bellwether cases.
    Although the 144 cases had many issues and facts in
    common, it was an impossibly large number to try
    individually, and too difficult to manage in one joint
    hearing. Therefore, [P]laintiffs’ counsel selected a group of
    six representative bellwether cases to be tried together in
    a consolidated manner. The evidence presented in this
    consolidated hearing regarding the factory, [asbestos]
    exposures to employees, the criteria for the diagnosis of
    asbestosis, the scientific evidence regarding asbestos
    exposure, and the potential for disease causation would be
    common to, and thus universally applicable to, all 144
    claims. The parties agreed that evidence on the general
    issues was to be part of the record for all [consolidated
    cases], to the extent the evidence was applicable to each
    [P]laintiff’s issues. The [B]ellwether [P]laintiffs’ individual
    medical and employment histories would be addressed, as
    would scientific evidence applicable to all 144 claims
    regarding asbestos-related-disease-causing capabilities,
    including the exposure and medical causation testimony.
    In addressing the bellwether cases first and presenting
    evidence applicable to all extant claims, the assumption
    was that after the six cases proceeded through trial,
    decision and appeal, the parties would be in a better
    position to evaluate the remaining claims. The remaining
    [consolidated cases] could then be potentially resolved, or
    they could proceed to abbreviated hearings for the
    introduction of evidence regarding their individual medical
    and employment information.
    One of these “initial six” [Bellwether P]laintiffs, Kirkland
    . . ., filed a Notice of Voluntary Dismissal with Prejudice on
    -3-
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    13 November 2012. This left five Bellwether Plaintiffs to
    proceed through trial, decision, and appeal.5 While under
    the jurisdiction of former Deputy Commissioner George
    Glenn, these matters were set on a course unlike that of
    most workers’ compensation cases, in that each side was
    given the opportunity to have a “full trial on the science”—
    with freedom to prosecute the cases according to the civil
    procedure used in superior court. The parties were
    permitted to take as many pre-hearing depositions as they
    wished and could call as many hearing witnesses as they
    determined to be necessary. The [B]ellwether [P]laintiffs’
    cases were heard together in a consolidated posture by
    former Deputy Commissioner Gheen on a special-set basis
    in various locations over the course of thirty-eight hearing
    days beginning 14 February 2011 and concluding 18
    February 2013. Former Deputy Commissioner Gheen’s
    hearing of these claims also involved substantial pre-trial
    proceedings.[6] Much of the evidence presented was
    “common” evidence applicable to all 144 extant claims.
    . . . . The Full Commission has reviewed and considered all
    hearing and deposition transcripts, along with all
    evidentiary exhibits, arguments, and briefs in reaching a
    decision in this claim.
    After hearings had already commenced, the deputy commissioner entered a 27
    July 2012 order requiring that “Plaintiffs who die during the pendency of these claims
    shall have at least 30 blocks of lung tissue preserved for autopsy and examination by
    an expert of Defendant’s choice.” The deputy commissioner based this order on the
    following findings and reasoning:
    [Defendant] denies that any of its employees, including
    claimants, would have had sufficient exposure to asbestos
    5   These five Bellwether Plaintiffs are the five Plaintiffs currently before us in the associated
    appeals.
    6  Three different deputy commissioners had been involved in the consolidated cases through
    entry of the initial opinions and awards for the bellwether cases by the deputy commissioner.
    -4-
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    from working at its facility to either cause or contribute to
    an asbestos related disease. It has presented the testimony
    of multiple credible expert witnesses in support of this
    defense.
    [] Plaintiffs’ claims against [Defendant] are based, in part,
    on a “B-read” of an x-ray provided by Plaintiffs’ expert.[7]
    As testified by the medical experts, radiological studies are
    only effective at identifying abnormal features on the x-ray
    that may be consistent with the disease of asbestosis, but
    also may be consistent with multiple other lung diseases.
    In order to make a diagnosis of asbestosis, a physician is
    called upon to rule out other possible conditions.
    [] The medical experts representing both parties have
    repeatedly testified that the only way to positively identify
    whether or not a lung condition or other cancer is caused
    by asbestos exposure is to take a sample of and examine
    the actual lung tissue. However, due to the risks involved,
    this procedure is not done while the patient is alive; it is
    commonly performed at autopsy.
    Therefore, the deputy commissioner ordered that Plaintiffs save lung tissue of any
    Plaintiffs who died so that their lung tissue could be examined. Plaintiffs did not
    fully comply with this order.
    The deputy commissioner reasoned in a 30 April 2013 order: “The diagnoses
    [of asbestosis], or lack thereof, by the experts is based on the reading of the same
    radiology. Both sides argue the veracity of their own experts.” “Given the opposing
    medical findings, . . . the undersigned Deputy Commissioner suggested to the
    parties” that they “jointly agree to independent medical experts or to experts chosen
    7   See findings of fact 25 to 28, below, for an explanation of the “B-read” process.
    -5-
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    by the Industrial Commission to review the radiology and any other relevant medical
    evidence, which experts’ opinion both parties would accept as final.” “Alternatively
    the parties debated whether the Plaintiffs should be compelled to submit to a high
    resolution computed tomography (hereinafter ‘HRCT’) scan to be interpreted by a
    physician selected by the Commission in order to determine the presence or absence
    of asbestosis.” Defendant agreed to the suggestion, and agreed to pay for the HRCT
    scans and associated costs, but Plaintiffs did not agree.
    During the hearings, “[m]uch of the evidence presented was ‘common’ evidence
    applicable to all 144 extant claims.”        Due to the resignation of the deputy
    commissioner who had presided over the hearings, the consolidated cases were
    assigned to a different deputy commissioner on 15 April 2015.            Plaintiffs and
    Defendant completed submission of evidence to the deputy commissioner, and made
    their closing oral arguments on 26 and 27 January 2016. The deputy commissioner
    filed his opinions and awards in the bellwether cases on 19 December 2016, denying
    the claims of all five Bellwether Plaintiffs. Plaintiffs appealed to the Full Commission
    on 21 December 2016. The Commission heard the matters on 29 June 2017, and also
    denied Plaintiffs’ claims by five opinions and awards entered 25 January 2018. The
    five 25 January 2018 opinions and awards filed in the consolidated cases each contain
    findings of fact common to all claims, which also include the ultimate findings and
    conclusions of law common to all claims.         Following the common findings and
    conclusions, each of the five opinions and awards before us contain findings of fact
    -6-
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    and conclusions of law sections that are specific to each individual Bellwether
    Plaintiff, as well as the Commission’s rulings denying each of the Bellwether
    Plaintiffs’ claims.
    Bellwether Plaintiffs appealed, and Plaintiffs and Defendant filed a motion
    with this Court on 30 May 2018 requesting consolidation of the bellwether cases for
    appeal.8 This Court ordered that a single record be submitted for all five bellwether
    cases, and that: “The parties shall each submit one general brief addressing common
    issues and five specific briefs addressing individual [P]laintiff issues.” Plaintiffs and
    Defendant each filed a single “general brief”—ostensibly the “general brief addressing
    common issues” ordered by this Court. Plaintiffs’ general brief is in reality the
    statement of facts for Plaintiffs’ individual briefs.         In addition, each of the five
    Bellwether Plaintiffs filed “specific” individual appellant briefs that are nearly
    identical, and almost exclusively argue common issues. Defendant responded to the
    Bellwether Plaintiffs’ individual briefs by filing five separate appellee briefs
    addressing the issues specific to each of the five Bellwether Plaintiffs. Although
    Plaintiffs’ individual briefs do not address the “common issues” separately from the
    “individual issues,” we address all Plaintiffs’ arguments concerning the “common
    issues” that were decided in the Commission’s 25 January 2018 opinions and awards
    in this opinion—COA18-770.            Our holdings for the “common issues” will be
    8 Because the “common issues” sections of the 25 January 2018 opinions and awards apply to
    all Consolidated Plaintiffs, we treat them as appellants as well.
    -7-
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    incorporated by reference in our opinions for the remaining four bellwether cases—
    COA18-766, COA18-767, COA18-768, and COA18-769. The “individual issues” will
    be addressed separately in each opinion.
    II. General Factual History
    Plaintiffs all allege they were exposed to asbestos while working at the factory,
    and further allege they developed compensable asbestos-related diseases as a result.
    As explained in a Fact Sheet published by the National Cancer Institute (“NCI”)—
    which was entered into evidence:9
    Asbestos is the name given to a group of minerals that
    occur naturally in the environment as bundles of fibers
    that can be separated into thin, durable threads. These
    fibers are resistant to heat, fire, and chemicals and do not
    conduct electricity. For these reasons, asbestos has been
    used widely in many industries.
    ....
    Asbestos minerals are divided into two major groups:
    Serpentine asbestos and amphibole asbestos. Serpentine
    asbestos includes the mineral chrysotile, which has long,
    curly fibers that can be woven. Chrysotile asbestos is the
    form that has been used most widely in commercial
    applications. Amphibole asbestos has straight, needle-like
    fibers that are more brittle than those of serpentine
    asbestos and are more limited in their ability to be
    fabricated.
    9   We include this NCI publication as a general introduction to asbestos, asbestos-exposure,
    and related disease. This is just one piece of evidence considered by the Commission—it was not
    specifically adopted by the Commission in its opinions and awards.
    -8-
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    National Cancer Institute, U.S. Department of Health and Human Services, Fact
    Sheet: Asbestos Exposure and Cancer Risk 1 (1 May 2009) (“NCI Fact Sheet”)
    (citations omitted). According to the NCI Fact Sheet:
    People may be exposed to asbestos in their workplace, their
    communities, or their homes. If products containing
    asbestos are disturbed, tiny asbestos fibers are released
    into the air. When asbestos fibers are breathed in, they
    may get trapped in the lungs and remain there for a long
    time. Over time, these fibers can accumulate and cause
    scarring and inflammation, which can affect breathing and
    lead to serious health problems.
    . . . . According to [the International Agency for Research
    on Cancer], there is sufficient evidence that asbestos
    causes mesothelioma (a relatively rare cancer of the thin
    membranes that line the chest and abdomen), and cancers
    of the lung, larynx, and ovary.            Although rare,
    mesothelioma is the most common form of cancer
    associated with asbestos exposure. There is limited
    evidence that asbestos exposure is linked to increased risks
    of cancers of the stomach, pharynx, and colorectum.
    Asbestos exposure may also increase the risk of asbestosis
    (an inflammatory condition affecting the lungs that can
    cause shortness of breath, coughing, and permanent lung
    damage) and other nonmalignant lung and pleural
    disorders, including pleural plaques (changes in the
    membranes surrounding the lung), pleural thickening, and
    benign pleural effusions (abnormal collections of fluid
    between the thin layers of tissue lining the lungs and the
    wall of the chest cavity).
    ....
    Everyone is exposed to asbestos at some time during their
    life. Low levels of asbestos are present in the air, water,
    and soil. However, most people do not become ill from their
    exposure. People who become ill from asbestos are usually
    -9-
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    those who are exposed to it on a regular basis, most often
    in a job where they work directly with the material or
    through substantial environmental contact.
    ....
    Although it is clear that the health risks from asbestos
    exposure increase with heavier exposure and longer
    exposure time, investigators have found asbestos-related
    diseases in individuals with only brief exposures.
    Generally, those who develop asbestos-related diseases
    show no signs of illness for a long time after exposure. It
    can take from 10 to 40 years or more for symptoms of an
    asbestos-related condition to appear.
    ....
    Several factors can help to determine how asbestos
    exposure affects an individual, including:
    • Dose (how much asbestos an individual was exposed
    to).
    • Duration (how long an individual was exposed).
    • Size, shape, and chemical makeup of the asbestos
    fibers.
    • Source of the exposure.
    • Individual risk factors, such as smoking and pre-
    existing lung disease.
    Although all forms of asbestos are considered hazardous,
    different types of asbestos fibers may be associated with
    different health risks. For example, the results of several
    studies suggest that amphibole forms of asbestos may be
    more harmful than chrysotile, particularly for
    mesothelioma risk, because they tend to stay in the lungs
    for a longer period of time.
    
    Id. at 2-3
    (citations omitted). The NCI Fact Sheet also states that initial examination
    for someone who suspects they may have an asbestos-related disease would generally
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    include “[a] thorough physical examination, including a chest x-ray and lung function
    tests[.] . . . . Although chest x-rays cannot detect asbestos fibers in the lungs, they
    can help identify any early signs of lung disease resulting from asbestos exposure.”
    
    Id. at 4
    (citations omitted). However, the NCI further stated: “A lung biopsy, which
    detects microscopic asbestos fibers in pieces of lung tissue removed by surgery, is the
    most reliable test to confirm exposure to asbestos.” 
    Id. Plaintiffs worked
    in different sections of the factory, but all allege they were
    exposed to airborne asbestos in quantities and of a type sufficient to cause asbestos-
    related diseases—primarily asbestosis. The Commission made the following relevant
    findings of fact related to the “common issues” raised by Plaintiffs’ claims:
    1. Asbestos is a generic term for a group of six naturally-
    occurring, fibrous silicate minerals that are ubiquitous in
    ambient air. The general public is exposed to asbestos from
    natural and artificial sources through food, water, and in
    other ways. The background level of asbestos to which the
    general public is exposed varies based on several factors
    including geography and proximity to urban centers. Low
    levels of asbestos can be found in the lungs of virtually
    100% of the general population. [N.C.G.S.] § 97-62 defines
    asbestosis as “a characteristic fibrotic condition of the
    lungs caused by the inhalation of asbestos dust.”
    2. Plaintiffs allege that they contracted asbestosis caused
    by exposure to airborne asbestos during employment with
    [D]efendant at the . . . factory[.]     Additionally, some
    Plaintiffs allege that they also contracted diseases other
    than asbestosis caused by exposure to airborne asbestos
    during employment at [the] factory. Asbestos is not a tire
    component. The [P]laintiffs allege workplace exposure in
    the factory from one or more of four main sources: 1)
    airborne asbestos originating from damaged or
    - 11 -
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    deteriorated asbestos-containing pipe insulation; 2)
    powdered talc allegedly contaminated with asbestos used
    as a non-stick agent in certain areas of the factory; 3)
    asbestos-containing dust released into the air by sawing
    and/or otherwise working with asbestos-containing
    gaskets; and 4) airborne asbestos-containing brake dust
    that allegedly emanated from forklifts and other factory
    vehicles during maintenance and use. Plaintiffs allege that
    they were exposed to asbestos through one or more of these
    methods in such form and quantity and with such
    frequency that it caused asbestosis.
    3. The . . . factory was constructed in the late 1960s and
    began manufacturing tires by 1969. . . . . The factory
    ceased tire production on 4 July 2006. . . . .
    4. The tire-making process began in the Banbury/mixing
    department, a three-story area open to the rest of the
    factory. On the top floor of the Banbury/mixing area,
    chemicals and rubber were received, weighed, and mixed.
    On the second floor of this area, these raw materials were
    put into heated mixing machines. From these mixers the
    material was dropped down chutes to the mills on the main
    floor. The mills pressed the chunks of rubber material into
    sheets. The sheets of rubber were then hung on a line and
    dried using fans. Once dry, the sheets were put on pallets
    and sent to the “calendaring and extruding” area.
    5. In the calendaring and extruding area, the rubber
    material was compressed into different thicknesses,
    shapes, and sizes for eventual use as the different
    components of a tire. . . . . The compressed rubber was
    then transferred to the “stock prep” area, where it was cut
    to the correct dimensions for tire building.
    6. In the “tire building” area, all of the tire pieces were
    layered together and pressed in a tire-building machine.
    . . . . The “green tires” were then transported to the curing
    department.
    7. There were 147 clam-shell-shaped curing presses/ovens
    - 12 -
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    in the curing department. . . . . The curing process, during
    which the “green tires” were placed in a mold and
    vulcanized under heat and pressure, was very hot and was
    operated by steam. For this reason, the curing area had
    more condensate and steam piping than any other area in
    the factory. Much of this piping was located in trenches
    that ran to the curing presses/ovens.
    8. After curing, the tires went to the “final finish” area
    where they were trimmed, cleaned, and inspected. The
    tires that passed inspection were put on pallets and
    transported to the warehouse[.]
    9. Steam and condensate pipes ran throughout the factory.
    . . . . There were at least 26,180 linear feet of insulated
    steam and condensate piping in the factory. The insulation
    was comprised of one to two inches of an
    asbestos-containing cement, Thermobestos, encapsulating
    the steam and condensate pipes. The pipes had protective
    canvas and glue surrounding the Thermobestos. Asbestos
    insulation was removed from the market in the early 1970s
    and, as such, expansions at the . . . factory after a certain
    date would not have included the installation of asbestos-
    encapsulated piping. Most of the insulated steam and
    condensate piping was at ceiling level, 20-30 feet above the
    factory floor, or below floor level in the trenches that ran
    between and into the curing presses. The floor-level and
    trench-level pipe insulation was susceptible to damage by
    foot traffic.    Forklifts could damage floor-level pipe
    insulation and also could damage pipe insulation at higher
    levels. For example, while stacking tires high in the
    warehouse, it was possible for the forklift payloads to strike
    the insulated piping.
    10. Plaintiffs allege exposure to airborne asbestos
    originating from deteriorated pipe insulation. Plaintiffs
    allege that it was damaged through external molestation
    by workers walking on pipes, climbing on pipes, and
    striking the pipes with forklifts and forklift payloads.
    Plaintiffs also argue that internal pipe damage from
    ruptures forced steam to leak out of the pipes with
    - 13 -
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    sufficient force to cause insulation damage and cause
    asbestos to become airborne. Plaintiffs further allege that
    workers used compressed air near the damaged insulation,
    causing asbestos to become airborne. There is conflicting
    evidence regarding the amount of pipe insulation damage
    present at [the] factory.
    11. The highest concentration of insulated piping in the
    factory existed in the curing department, with much of the
    piping at or below floor level. Plaintiffs allege that workers
    used a band saw to cut large asbestos-containing gaskets
    in the curing department. If [P]laintiffs’ allegations are
    correct, it would be logical to expect high levels of airborne
    particulates in the curing department originating from
    damaged pipe insulation and gasket-sawing. However, the
    greater weight of the evidence does not support this
    conclusion.
    12. In 1979, the . . . factory took part in an air contaminant
    assessment study in conjunction with The National
    Institute for Occupational Safety and Health (hereinafter
    “NIOSH”). At the time, NIOSH was studying the best
    methods and technologies to control air quality in the tire
    industry.     The report reflects that [the] factory was
    selected for the study because it had “among the better
    controls for air contaminants in the industry.” NIOSH
    performed area and personal air monitoring in each area of
    the plant that it expected to find measurable dust or
    emissions. Specifically, NIOSH measured for dust—both
    airborne and respirable, as well as petroleum distillates,
    rubber solvent, Benzene, and Toulene.                The dust
    measurements would have measured any particulates in
    the air—whether the particulates were asbestos, talc, or
    something else. The 1979 NIOSH dust measurements
    found that the measured dust levels in the curing
    department were 1/100th of the permissible level. This was
    possibly due to the curing department’s powerful exhaust
    system, which drew air up and out of the area. Except for
    an outlier measurement created by an employee jumping
    up and down in a dusty trash bin, the 1979 dust
    measurements at [the] factory were five to ten times less
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    than the permissible exposure level (hereinafter “PEL”) in
    place in 2013. NIOSH concluded that the particulate and
    vapor concentrations at [the factory] were well below the
    PEL established by the Occupational Safety and Health
    Administration (hereinafter OSHA), NIOSH, and the
    American Conference of Governmental Industrial
    Hygienists. NIOSH also concluded that the environmental
    controls (exhaust and ventilation systems) were effective.
    13. There was also environmental air sampling for asbestos
    at [the] factory in 1985 when asbestos-containing
    insulation was removed from a furnace on the third floor of
    the mixing area. This sampling was done with background
    air monitoring as well as with personal air monitors on the
    personnel conducting the removal. In 1985, there were no
    regulations regarding wetting down insulation as it was
    removed. Therefore, the air measurements taken during
    this removal process record a scenario very favorable for
    the creation of airborne dust.       However, the 1985
    background air monitoring that took place showed results
    well below the then-current OSHA PEL. The highest
    recorded personal air monitoring result during the removal
    was also below the then-existing OSHA PEL.
    14. As a result of the 1986 federal asbestos regulations,
    large-scale asbestos abatement procedures were
    undertaken at [the] factory. This process required pre-
    abatement area air quality monitoring to measure pre-
    removal levels. For this reason, there were background air
    samples collected for abatement projects in 1989 (curing),
    1995 (calendar and extruding), and 2003 (powerhouse). In
    all of these areas, these measurements show that at no
    time was the potential exposure above the OSHA PEL.
    Background monitoring reflected levels to which the public
    at large is exposed.
    15. In areas with ceiling-level piping, such as the
    warehouse, the evidence demonstrates that any small
    amount of asbestos potentially disturbed and released at
    ceiling level due to pipe insulation damage would have
    dissipated before reaching workers and would not have
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    created any meaningful exposure.
    ....
    17. Plaintiffs also allege exposure to asbestos through the
    inhalation of powdered talc which they allege contained
    asbestos.      Talc is used ubiquitously by the general
    population in things such as makeup and baby powder. It
    is the most common non-asbestos mineral found in general
    population lung tissue. Talc was used in [the] factory as a
    non-stick agent. However, the amount of talc used in the
    . . . factory is a contested factual issue. Defendant avers
    that routinely, workers mistook other powdery materials
    used in great quantities at the factory for talc. Specifically,
    [D]efendant contends that clay [kaolin], calcium carbonate,
    and zinc oxide were commonly used in vastly larger
    quantities and were routinely incorrectly referred to by the
    workers as “talc.” . . . .
    18. While talc from certain mines is known to be
    contaminated by asbestos, there was disagreement among
    the experts regarding the likelihood of asbestos being a
    contaminant in the talc used at [the] plant. Furthermore,
    in 1995, air monitoring was done in the calendaring area
    while calendaring work continued.         Plaintiffs allege
    significant talc usage in this area.         If [P]laintiffs’
    allegations are correct, it would be logical to expect high
    levels of airborne particulates in calendaring. However,
    the 1995 measurements, performed as calendaring work
    continued, found airborne particulate levels well below the
    then-existing OSHA PEL, and EPA clearance levels.
    ....
    20. . . . . There was contradicting testimony on the issue
    of cutting gaskets—with some witnesses testifying that
    gaskets came from the manufacturer already made to fit
    and did not require any sawing and other testimony that
    any such sawing, if it took place, would have been done in
    the maintenance shop, not in curing.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    ....
    24. In 1986, federal government regulations mandated new
    procedures to identify, encapsulate, and abate workplace
    asbestos. As part of these new regulations, in 1987, certain
    employees at [the] factory were trained for the possibility
    that small asbestos removals would have to be performed
    by [Defendant’s] employees. . . . . All removal and
    abatement procedures were performed by outside
    contractors. Subsequent to the 1986 regulations, the new
    asbestos management policies were made known to all
    employees, masks were provided, and safety protocols,
    such as the prohibition of using compressed air on damaged
    insulation, were enacted. Furthermore, known asbestos-
    containing materials were labeled, encapsulated, and
    removed.
    25. An asbestosis B-read is a test in which NIOSH-certified
    physicians view a patient’s chest x-ray and score it from 0/0
    (for normal lungs) through 3/3 (for lungs with severe
    disease). B-readers become certified (and re-certified every
    4 years) based on their tested proficiency in scoring a set of
    standard x-rays. The first number in a B-read score
    reflects that reader’s first impression of the film, with the
    second number reflecting a different number if the reader
    has a “second thought” or if the reader thinks another B-
    reader could arrive at a different conclusion. For example,
    a 1/0 score reflects a B-reader’s conclusion that the film is
    mildly abnormal, but that another B-reader could read the
    film as normal.
    26. The 1986 American Thoracic Society criteria required a
    B-read to be 1/1 or greater before the result was considered
    consistent with asbestosis. The 1986 criteria also stated:
    “the benefit of the doubt should be given whenever the
    clinical features and occupational exposure data are
    compatible with the diagnosis.” The 2004 American
    Thoracic Society criteria liberalized the standard to define
    a 1/0 read or greater as consistent with asbestosis, but
    removed the “benefit of the doubt” language. Many
    common non-asbestos-related conditions are consistent
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    with a 1/0 B-read. For example, cigarette smoking can
    cause opacities consistent with a 1/0 B-read.
    27. The [P]laintiffs in these cases took part in a mass
    screening of chest x-rays of [Defendant’s] former . . . factory
    workers.       This mass screening was organized by
    [P]laintiffs’ attorneys. These x-rays were reviewed by B-
    readers selected by [P]laintiffs’ attorneys. Over 80% of
    [P]laintiffs in these cases were evaluated by [P]laintiffs B-
    readers to have “1/0” B-reads. Plaintiffs were subsequently
    referred by [P]laintiffs’ attorneys for mass diagnostic
    examinations at a hotel in Charlotte performed by
    pulmonologists selected by [P]laintiffs’ attorneys.
    28. Defendant’s B-readers evaluated the [P]laintiffs’ x-rays
    as 0/0. This consistent disparity of B-reads, which, by
    definition, are meant to be read to a consistent standard,
    raises the issue of possible B-reading bias by one or both
    sides.
    29. Asbestos-related diseases follow a dose-response
    relationship—the higher the cumulative [asbestos]
    exposure dose, the greater the risk of disease, with
    asbestosis generally requiring the highest dose. Pleural
    plaques, pleural thickening, and mesothelioma are
    asbestos-related conditions that generally form at a lower
    dose.
    30. In the general population, approximately 80% of people
    diagnosed with asbestosis will also have bilateral pleural
    plaques. However, experts in these cases only identified
    about 10% of the [P]laintiffs diagnosed with asbestosis as
    also having bilateral pleural plaques. This outcome is
    statistically improbable. Because pleural plaques require
    less exposure, it is not logical that such a large group
    diagnosed with asbestosis would have so few with pleural
    plaques.
    31. Pursuant to an order issued by former Deputy
    Commissioner Gheen, [D]efendant has been entitled to
    autopsies and lung tissue examinations of deceased
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    [P]laintiffs to allow pathological examinations. Although
    18 [P]laintiffs have died to date, [D]efendant has only been
    able to obtain autopsy results and tissue examinations of
    five deceased [P]laintiffs—Walter Hinson, Johnnie Jones,
    Charles Gibson, Homer Hunt, and Lloyd Cox. Walter
    Hinson is the only [Bellwether P]laintiff who had
    post-mortem pathology[.]
    32. Pathological examination of lung tissue is a definitive
    method of determining whether an individual has an
    asbestos-related disease. x-rays are inherently limited in
    that they can only identify markings that are consistent
    with a pneumoconiosis such as asbestosis.            These
    markings, as seen on radiological scans, can also be
    consistent with a number of unrelated conditions and
    diseases.
    33. The accepted scientific method to diagnose asbestosis
    pathologically requires diffuse interstitial fibrosis AND
    either two or more asbestos bodies per centimeter squared
    OR a count of uncoated asbestos fibers that falls within
    that lab’s range for asbestosis (accounting for the
    background levels found in that lab’s reference
    population/control group). Labs also may have different
    methodologies to digest and identify fibers, making cross-
    lab comparisons problematic. Asbestos bodies are fibers
    that have been coated by the body as a defense mechanism.
    Diffuse interstitial fibrosis or scarring can be caused by
    numerous things other than asbestosis. Many non-
    asbestos-related diseases and conditions can result in a 1/0
    B-read.
    34. Of the five deceased [P]laintiffs who had post-mortem
    pathological study of their lung tissue, (Walter Hinson,
    Johnnie Jones, Charles Gibson, Homer Hunt, and Lloyd
    Cox), none had pathological evidence of asbestosis.
    Pathology is the most reliable method to diagnose
    asbestosis.
    35. Pursuant to the Helsinki, OSHA, and NIOSH
    standards, fibers shorter than 5 micrometers [or microns]
    - 19 -
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    are not counted pathologically for purposes of asbestosis
    diagnosis or risk assessment. Fibers shorter than 5
    micrometers, due to their length, are cleared quickly by the
    lungs and are not believed to contribute to the disease.
    Only fibers longer than 5 micrometers become lodged into
    the lung tissue, as they are too big to navigate through the
    lymphatic channels to be cleared by a human lung’s
    defense mechanisms.
    36. Samples of the pipe insulation at the . . . factory show
    the presence of two types of asbestos—amosite and
    chrysotile. Amosite is an amphibole. Chrysotile is a type
    of [serpentine] asbestos, often shorter than five
    micrometers, that is particularly susceptible to being
    broken down quickly in acidic environments, such as a
    human lung. Due to its length and fragility in the human
    lung, the clearance half-life of chrysotile asbestos in
    humans has been estimated to be a few weeks to a few
    months. Plaintiffs argue that the tissue fiber analyses in
    these cases under-assessed the number of fibers by not
    counting the chrysotile fibers because they are quickly
    cleared from the human lung. Many experts believe that
    chrysotile asbestos does not cause or contribute to
    asbestosis or asbestos-related disease due to its short
    clearance half-life and that fact that persistence of a fiber
    within the lung is a crucial determinant of its
    pathogenicity. By contrast, amphibole asbestos fibers are
    not susceptible to being dissolved by lung tissue and have
    a clearance half-life in the human body measured in
    decades. Because the pipe insulation at the . . . factory had
    both chrysotile and amphibole asbestos, the [P]laintiffs’
    lung pathology would show occupational exposure, if it
    existed, in the form of amphibole fibers.
    37. [Plaintiff] Hinson . . . worked for 32 years, mainly in the
    curing department. The curing department had the
    highest concentration of insulated piping in the factory,
    with much of it at floor level or in exposed trenches.
    According to [Plaintiff] Hinson, he was also exposed to
    significant asbestos dust from using a band saw to cut large
    asbestos gaskets. If [P]laintiffs’ arguments are correct,
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    [Plaintiff] Hinson would have been exposed to a significant
    amount of airborne asbestos. [Plaintiff] Hinson was given
    a 1/0 B-read by Dr. James Johnson[.] Dr. Craig Hart at
    York pathology performed [P]laintiff Hinson’s lung
    autopsy. Dr. Hart found no evidence of asbestos bodies or
    fibrosis, but did see evidence of smoking. The tissue was
    sent to Dr. Oury, who examined the sample and confirmed
    Dr. Hart’s conclusions. Although it was not required for
    diagnostic purposes due to the lack of fibrosis, a fiber count
    analysis was done by Dr. Oury upon [D]efendant’s request.
    The fiber count analysis found 5 asbestos bodies per gram,
    which is a level well below that seen in individuals with
    asbestosis and in the range of control individuals with no
    history of [occupational] asbestos exposure.
    38. Decedent Johnnie Jones . . . worked for 25 years in the
    calendar area. If [P]laintiffs’ arguments are correct, he
    would have been subjected to significant airborne asbestos-
    contaminated talc exposure in his workplace environment.
    Decedent Johnnie Jones had a 1/0 B read from Dr. Crim.
    However, when Dr. Roggli performed a pathological
    examination of Jones’ lung tissue, he found no histologic
    evidence of asbestosis or elevated asbestos content. Based
    on decedent Jones’ employment history at [the factory] and
    his pathology results, Dr. Roggli testified that there was
    not sufficient exposure to asbestos at the factory . . . to
    contribute to or to cause an asbestos-related disease for Mr.
    Jones or anyone in his position.
    39. Decedent Charles Gibson . . . worked at the . . . factory
    . . . for 31 years—holding jobs in the tire-building and
    warehouse departments. If [P]laintiffs’ arguments are
    correct, Gibson would have been subjected to significant
    airborne asbestos exposure in his workplace environment.
    Decedent Gibson was found to have a 1/0 B-read according
    to Dr. Crim. Decedent Gibson’s lung tissue was collected
    by York Pathology Associates after his death. Dr. Jenkins
    with York Pathology performed a gross tissue examination.
    Dr. Jenkins found no pleural plaques. Dr. Oury also
    examined the tissue and found no evidence of pulmonary
    fibrosis, no asbestos bodies, and no fibers. Talc and
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    vermiculite were found, but the source of these materials
    was impossible to discern.
    40. Decedent Homer Hunt . . . was employed at the
    . . . factory for 17 years as a mechanic—working in all areas
    of the factory. Among many other tasks, decedent Hunt
    replaced forklift brakes. If [P]laintiffs’ arguments are
    correct, decedent Hunt would have been subjected to
    significant amounts of airborne asbestos-containing brake
    dust in his workplace environment. Decedent Hunt was a
    45-year smoker who died of lung cancer in 2012. His lung
    tissue was collected by York pathology pursuant to the
    Autopsy Order. Dr. Richard Johnson and Dr. Oury
    examined decedent Hunt’s lung tissue. No fibrosis was
    found in areas of the lung not impacted by the unrelated
    carcinoma tumor. Furthermore, there were no asbestos
    bodies or fibers found.
    41. Decedent Lloyd Cox . . . worked at [the] factory for 31
    years in the stock and bead prep area. Decedent Cox died
    in 2014 of viral pneumonitis complicated by other factors.
    Although decedent Cox had “end stage asbestosis” written
    on his death certificate by the Lancaster County coroner,
    this diagnosis is of dubious reliability in that it apparently
    has little or no scientific basis. The coroner does not have
    a college degree and did not consult with the county
    pathologist before writing that conclusion on the death
    certificate. Decedent Cox’s lung tissue was collected and
    examined by York Pathology Associates.                Surgical
    pathologist Dr. Sporn performed a “transbronchial biopsy.”
    Dr. Sporn did not find any asbestos bodies and no condition
    was found on the biopsy that would have been caused by or
    contributed to by asbestos exposure. Dr. Sporn articulated
    that viral pneumonia was the likely cause of death. Dr.
    Hart performed the pathology exam, microscopically and
    grossly, and found that there was no interstitial fibrosis, no
    asbestos bodies, no pleural plaques, no asbestos fibers, and
    no evidence of exposure to asbestos above the general
    population.
    42. Despite [P]laintiffs’ theories of exposure, pathology
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    results from the lung tissue of five long-term employees
    from a variety of departments and factory locations
    uniformly show a lack of fibrosis, a lack of asbestos bodies,
    and a lack of fibers.
    ....
    44. Drs. Ghio, Barrett, Goodman, and Alexander concluded
    that [P]laintiffs did not have findings consistent with
    diagnoses of asbestosis. Given the preponderance of the
    evidence in view of the entire record, their opinions are
    given greater weight than those of Drs. Crim, Ohar,
    Schwartz, and Frank [Plaintiffs’ experts].
    Plaintiffs argue that some of these findings are erroneous, incomplete, or misstate
    the facts. We will address Plaintiffs’ arguments concerning the findings of fact below.
    Based upon these common findings of fact, the Commission determined that Plaintiffs
    had not meet their burden of proving they were exposed to levels of hazardous
    airborne asbestos capable of causing—or significantly contributing to—their alleged
    asbestos-related diseases. Additional facts will be discussed below.
    III. Relevant Workers’ Compensation Law
    A. Standard of Review
    The issues before us are controlled by Article 1, Chapter 97 of the General
    Statutes—the “Workers’ Compensation Act” (the “Act”).         “The employee seeking
    workers’ compensation benefits bears the burden of proving every element of
    compensability. The degree of proof required of a claimant under the Act is the
    ‘greater weight’ or ‘preponderance’ of the evidence.” Hardin v. Motor Panels, Inc., 136
    - 23 -
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    N.C. App. 351, 354, 
    524 S.E.2d 368
    , 371 (2000) (citations omitted). This Court’s
    standard of review is well established:
    “Appellate review of an award from the Industrial
    Commission is generally limited to two issues: (i) whether
    the findings of fact are supported by competent evidence,
    and (ii) whether the conclusions of law are justified by the
    findings of fact.” Unchallenged findings of fact are
    presumed to be supported by competent evidence[.] The
    Commission’s conclusions of law are reviewed de novo.
    Penegar v. United Parcel Serv., __ N.C. App. __, __, 
    815 S.E.2d 391
    , 394 (2018)
    (citations omitted). “Whether an injury arose out of and in the course of employment
    is a mixed question of law and fact, and the Industrial Commission’s findings in this
    regard are conclusive on appeal if supported by competent evidence.” Culpepper v.
    Fairfield Sapphire Valley, 
    93 N.C. App. 242
    , 247, 
    377 S.E.2d 777
    , 780 (1989) (citation
    omitted).10 The Commission’s findings, including its ultimate findings, are binding
    “when they are supported by direct evidence or by reasonable inferences drawn from
    the record.” Kennedy v. Duke Univ. Med. Center, 
    101 N.C. App. 24
    , 30, 
    398 S.E.2d 677
    , 680 (1990) (citations omitted).            “[T]he Commission is required to evaluate the
    credibility of the evidence and reject any evidence it finds as not convincing.” Phillips
    v. U.S. Air, Inc., 
    120 N.C. App. 538
    , 542, 
    463 S.E.2d 259
    , 262 (1995) (citation omitted).
    [T]he Commission has sole authority to make findings of
    fact. This Court does not weigh the evidence. We
    determine only whether there is any evidence of substance
    in the record to support the Commission’s findings; if there
    10   We refer to the Commission’s resolution of these mixed questions of law and fact as “ultimate
    findings.”
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    is, we are bound by the findings, even though the record
    may contain evidence supporting findings contra. There
    must be a complete lack of competent supporting evidence
    to justify disregarding the Commission’s findings of fact.
    Where medical testimony is conflicting, the Commission
    decides which testimony to give the greater weight.
    Carroll v. Burlington Industries, 
    81 N.C. App. 384
    , 387-88, 
    344 S.E.2d 287
    , 289–90
    (1986) (citations omitted).
    B. Workers’ Compensation; Occupational Diseases
    Most, if not all, Consolidated Plaintiffs allege they developed asbestosis as a
    result of their work at the factory.11 See N.C.G.S. § 97-53(24) (2017). Two Bellwether
    Plaintiffs, Wilson and Epps, alleged they have occupational diseases as defined by
    N.C.G.S. § 97-53(13); colon cancer and tonsil cancer, respectively—caused by asbestos
    exposure at the factory. Normally, the Commission would first determine whether a
    plaintiff had proven an occupational disease, and only after determining that the
    plaintiff had met that burden would the Commission consider evidence related to
    compensability, or whether the occupational disease had any causal connection to the
    plaintiff’s employment.        However, for these cases we are asked to review the
    Commission’s determinations that conditions at the factory could not have exposed
    Consolidated Plaintiffs to airborne asbestos of a type and in sufficient amounts to
    cause asbestosis, or other asbestos-related diseases—before the Commission
    11 Or, for deceased Plaintiffs, their estates allege that the deceased Plaintiffs had developed
    asbestosis.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    determines whether any Consolidated Plaintiffs actually have asbestos-related
    diseases.12    In light of the unusual procedure employed, a review of workers’
    compensation law and procedure applicable to cases of alleged compensable asbestos-
    related diseases is appropriate.
    “The underlying purpose of [the 1929 adoption of the] Act . . . [wa]s to provide
    compensation for workmen who suffer disability by accident arising out of and in the
    course of their employment.” Henry v. Leather Co., 
    234 N.C. 126
    , 127, 
    66 S.E.2d 693
    ,
    694 (1951). Initially, the Act only allowed compensation for “injury by accident.” See
    
    id. at 127,
    66 S.E.2d at 694. However, the Act was amended in 1935 to include
    benefits for employees who developed compensable occupational diseases. 
    Id. at 128,
    66 S.E.2d at 694–95; N.C.G.S. § 97-52 (2017). The amendment enumerated specific
    diseases—like asbestosis—that were designated as “‘occupational diseases within the
    meaning of [Article 1].’” Henry, 234 N.C. at 
    128, 66 S.E.2d at 694
    (citation omitted);
    N.C.G.S. § 97-53. Later, the Act was amended to allow employees to prove that a
    disease not specifically enumerated in N.C.G.S. § 97-53 was a “compensable
    occupational disease” based upon the specific facts of the plaintiff’s claim. N.C.G.S.
    § 97-53(13). N.C.G.S. § 97-53(13) states in relevant part: “Any disease . . . which is
    proven to be due to causes and conditions which are characteristic of and peculiar to
    a particular trade, occupation or employment, but excluding all ordinary diseases of
    12  Excluding the Bellwether Plaintiffs, for whom the Commission has concluded no asbestos-
    related diseases have been proven to exist.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    life to which the general public is equally exposed outside of the employment” “shall
    be deemed to be [an] occupational disease[] within the meaning of” the Act. N.C.G.S.
    § 97-53(13).
    “[T]he addition of G.S. 97-53 to the Act ‘in nowise relaxed the fundamental
    principle which requires proof of causal relation between injury and employment.’”
    Booker v. Medical Center, 
    297 N.C. 458
    , 475, 
    256 S.E.2d 189
    , 200 (1979) (citations
    omitted). “It is overwhelmingly apparent that . . . disablement resulting from an
    occupational disease . . . must arise out of and in the course of the employment, i.e.,
    there must be some causal relation between the injury and the employment[.]”
    Morrison v. Burlington Industries, 
    304 N.C. 1
    , 12, 
    282 S.E.2d 458
    , 466 (1981).
    Now, all provisions of the Act that had formerly applied only to injuries by
    accident also apply to compensable occupational diseases—so long as they do not
    conflict with more specific provisions in the Act specifically pertaining to occupational
    diseases. N.C.G.S. § 97-52. “[A]n employee becoming disabled by asbestosis [or other
    occupational disease] . . . within the terms of the specific definition embodied in G.S.
    [§] 97-54 should be entitled to ordinary compensation measured by the general
    provisions of the . . . Act. G.S. [§] 97-64.” Young v. Whitehall Co., 
    229 N.C. 360
    , 366,
    
    49 S.E.2d 797
    , 801 (1948).
    Therefore, the Act now provides that the terms “injury,” “personal injury,” or
    “injury by accident” also encompass “[d]isablement or death of an employee resulting
    from an occupational disease described in G.S. 97-53[.]” N.C.G.S. § 97-52; N.C.G.S. §
    - 27 -
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    97-2(6) (2017) (emphasis added) (“Injury.—‘Injury and personal injury’ shall mean
    only injury by accident arising out of and in the course of the employment[.]”); see also
    Henry, 234 N.C. at 
    128, 66 S.E.2d at 694
    (citation omitted) (The amendment also
    “broadened or extended the meaning of the word ‘accident’ as used in the original Act
    so as to include a disablement or death resulting from an occupational disease
    described in G.S. § 97-53[.]”).    “Nothing is said in [N.C.G.S. § 97-52] or cases
    construing it which could be interpreted as allowing compensation for injury from
    occupational disease which falls short of ‘disablement.’”       Harrell v. Harriet and
    Henderson Yarns, 
    56 N.C. App. 697
    , 699, 
    289 S.E.2d 846
    , 847 (1982); N.C.G.S. § 97-
    64 (2017).
    Generally, “disablement” means a diminished ability to earn wages resulting
    from an injury sustained due to employment. N.C.G.S. § 97-2(9); N.C.G.S. § 97-54
    (2017).   “The term ‘disability’ as used in [the Act] means the state of being
    incapacitated as the term is used in defining ‘disablement’ in G.S. 97-54[,]” N.C.G.S.
    § 97-55 (2017), and is therefore, in all ways relevant to this opinion, synonymous with
    “disablement.” “The term ‘death’ as a basis for a right to compensation means only
    death resulting from an injury.” N.C.G.S. § 97-2(10).
    In order to be compensable, a plaintiff-employee must prove, inter alia, that
    the plaintiff’s alleged occupational disease, including one—like asbestosis—that is
    specifically enumerated in N.C.G.S. § 97-53, “‘was incident to or the result of the
    particular employment in which the workman was engaged.’” Booker, 297 N.C. at
    - 28 -
    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    
    475, 256 S.E.2d at 200
    (citation omitted). Stated differently, “to demonstrate a causal
    link between the condition for which plaintiff seeks compensation and plaintiff’s
    employment[,]” the plaintiff must prove that the plaintiff’s “employment ‘significantly
    contributed to, or was a significant causal factor in, the disease’s development.’”
    James v. Perdue Farms, Inc., 
    160 N.C. App. 560
    , 562, 
    586 S.E.2d 557
    , 560 (2003)
    (citations omitted). As noted in finding of fact 2, Consolidated Plaintiffs do not argue
    that employment at the factory “significantly contributed to” the development of their
    alleged asbestosis diagnoses. Instead, “Plaintiffs allege that they were [each] exposed
    to asbestos [while working at the factory] in such form and quantity and with such
    frequency that it caused asbestosis.” (Emphasis added). Therefore, with respect to
    asbestosis, our review will be limited to whether Plaintiffs proved work at the factory
    “was a significant causal factor in” development of Plaintiffs’ alleged asbestosis. 
    Id. Pursuant to
    N.C.G.S. § 97-53(13), colon cancer or tonsil cancer
    may be an occupational disease provided the occupation in
    question exposed the worker to a greater risk of contracting
    this disease than members of the public generally, and
    provided the worker’s exposure to [asbestos] significantly
    contributed to, or was a significant causal factor in, the
    disease’s development. This is so even if other non-work-
    related factors also make significant contributions, or were
    significant causal factors.
    Rutledge v. Tultex Corp., 
    308 N.C. 85
    , 101, 
    301 S.E.2d 359
    , 369–70 (1983) (citation
    omitted). When determining whether an occupational disease is compensable, “[t]he
    factual inquiry . . . should be whether the occupational exposure was such a
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    significant factor in the disease’s development that without it the disease would not
    have developed to such an extent that it caused the physical disability which resulted
    in claimant’s incapacity for work.” 
    Id. at 102,
    301 S.E.2d at 370. “[I]f a disease is
    produced by some extrinsic or independent agency, it may not be imputed to the
    occupation or the employment.” 
    Id. at 103,
    301 S.E.2d at 370 (citations omitted).
    Therefore, generally, in order for a claim of occupational disease to be
    compensable under the Act, the plaintiff must prove (1) that the plaintiff has an
    injury—specifically an occupational disease; (2) that the occupational disease “arose
    out of” and “in the course of” some employment, Gallimore v. Marilyn’s Shoes, 
    292 N.C. 399
    , 402–03, 
    233 S.E.2d 529
    , 531–32 (1977),—i.e. that the “employment
    ‘significantly contributed to, or was a significant causal factor in, the disease’s
    development[,]’” 
    James, 160 N.C. App. at 562
    , 586 S.E.2d at 560 (citations omitted);
    and (3) that the occupational disease resulted in “disability,” N.C.G.S. § 97-54.13 “In
    general, the term ‘in the course of’ refers to the time, place and circumstances under
    13  Generally, Plaintiff Hinson’s estate would not need to prove that his employment with
    Defendant was the “origin or cause” of his disablement, Penegar, __ N.C. App. at __, 815 S.E.2d at
    398—it could prove a causal connection between his alleged asbestosis and any employment prior to
    or including his work at the factory. Defendant would then be liable for any disability due to Plaintiff
    Hinson’s asbestosis if his estate could also prove that he “was last injuriously exposed to the hazards
    of” asbestosis, as defined in N.C.G.S. § 97-57, while working for Defendant. N.C.G.S. § 97-57 (2017).
    However, the Commission found as fact that Plaintiffs all “allege that they contracted asbestosis
    caused by exposure to airborne asbestos . . . during employment with [D]efendant[,]” and that Plaintiff
    “Hinson apparently had no exposure to asbestos through his prior employment.” Plaintiff Hinson’s
    Estate does not contest these findings, so it must prove that Plaintiff Hinson developed asbestosis due
    to exposure to asbestos while working at the factory—and that his asbestosis led to disablement as
    defined by the Act at some point prior to his death. N.C.G.S. § 97-52; N.C.G.S. § 97-2(6); N.C.G.S. §
    97-54.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    which an accident occurs, while the term ‘arising out of’ refers to the origin or causal
    connection of the accidental injury to the employment.” 
    Gallimore, 292 N.C. at 402
    03, 233 S.E.2d at 531
    –32 (citations omitted). “In determining whether a claimant’s
    [alleged occupational] exposure to [asbestos] has significantly contributed to, or been
    a significant causative factor in, [an asbestos-related] disease, the Commission may,
    of course, consider medical testimony, but its consideration is not limited to such
    testimony.” 
    Rutledge, 308 N.C. at 105
    , 301 S.E.2d at 372 (citation omitted). Our
    Supreme Court has stated:
    In the case of occupational diseases proof of a causal
    connection between the disease and the employee’s
    occupation must of necessity be based on circumstantial
    evidence. Among the [non-exclusive] circumstances which
    may be considered are the following: (1) the extent of
    exposure to the disease or disease-causing agents during
    employment, (2) the extent of exposure outside
    employment, and (3) absence of the disease prior to the
    work-related exposure as shown by the employee’s medical
    history.
    
    Booker, 297 N.C. at 476
    , 256 S.E.2d at 200 (citations omitted) (emphasis added).
    Only after a plaintiff has proven that the plaintiff’s occupational disease is
    compensable, must the plaintiff prove a defendant-employer’s liability—by proving
    the plaintiff was “last injuriously exposed” to the hazards of the disease while working
    for that defendant-employer. N.C.G.S. § 97-57. N.C.G.S. § 97-57 states in part:
    In any case where compensation is payable for an
    occupational disease,[14] the employer in whose
    14   I.e., once the plaintiff has proven a compensable occupational disease.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    employment the employee was last injuriously exposed to
    the hazards of such disease . . . shall be liable.
    For the purpose of this section when an employee has been
    exposed to the hazards of asbestosis . . . for as much as 30
    working days, or parts thereof, within seven consecutive
    calendar months, such exposure shall be deemed injurious
    but any less exposure shall not be deemed injurious[.]
    N.C.G.S. § 97-57 (emphasis added). If a plaintiff fails to prove that the plaintiff has
    a compensable occupational disease, compensation will be denied and “last injurious
    exposure” analysis pursuant to N.C.G.S. § 97-57 will not be necessary. N.C.G.S. § 97-
    57 is not meant to establish the burden for proving a causal relationship between a
    particular employment and development of an occupational disease. Instead:
    [T]he purpose of the “last injurious exposure” doctrine is
    “to eliminate the need for complex and expensive litigation
    of the issue of relative contribution by each of several
    employments to a plaintiff’s occupational disease.” The
    doctrine provides a plaintiff with a reduced burden by
    requiring only a showing that the occupational exposure
    augmented a disease, “however slight[,]” as opposed to
    demonstrating how much each exposure resulted in the
    disease.
    Penegar, __ N.C. App. at __, 815 S.E.2d at 398 (citations omitted). In the present
    cases, Plaintiffs alleged their sole occupational exposure to asbestos occurred working
    in the factory.
    C. The “Bellwether Cases” Approach
    As noted above, in the ordinary case—because it is the plaintiffs’ burden to
    prove they “suffer[ed] from [] compensable occupational disease[s,]” Hardin, 136 N.C.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    App. at 
    354, 524 S.E.2d at 371
    (citations omitted)—the Commission would first
    determine whether the plaintiffs had met their burden of proving they suffered from
    an occupational disease. If the plaintiffs failed to meet that burden, the Commission
    could deny their claims without making any further determinations such as
    compensability and liability.       See, e.g., Payne v. Charlotte Heating & Air
    Conditioning, 
    172 N.C. App. 496
    , 
    616 S.E.2d 356
    (2005); Clark v. ITT Grinnell Ind.
    Piping, Inc., 
    141 N.C. App. 417
    , 
    539 S.E.2d 369
    (2000).
    However, because of the bellwether cases approach, the Commission addressed
    the issues common to all Consolidated Plaintiffs first—and only then made individual
    determinations specific to the individual Bellwether Plaintiffs. The Commission’s
    determinations concerning whether any individual Consolidated Plaintiff had
    asbestosis will necessarily require review of the medical evidence specifically relevant
    to that particular Plaintiff—i.e., thorough review of all relevant documentary and
    testimonial evidence for every one of the 144 Consolidated Plaintiffs. Pursuant to the
    bellwether cases approach, review of the medical evidence for the alleged asbestos-
    related diseases for all Consolidated Plaintiffs will only be necessary if Plaintiffs first
    prove that working in the factory exposed them to asbestos, in a form and in
    quantities, that could have caused the alleged asbestosis; or caused—or significantly
    contributed to—the development of other alleged asbestos-related diseases.
    The Commission determined employment in the factory did not expose
    Plaintiffs to airborne asbestos of a kind and in amounts sufficient to cause or
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    contribute to asbestosis.15 If this determination is affirmed, most, if not all, of the
    Consolidated Plaintiffs’ asbestosis claims can be decided without the time and cost
    involved in conducting full hearings for all 144 cases. 
    Booker, 297 N.C. at 472
    , 256
    S.E.2d at 198. In light of the inverted approach applied in the bellwether cases, the
    Commission essentially assumed, arguendo, that the Consolidated Plaintiffs actually
    had asbestosis that resulted in disablement or death—and focused solely on whether
    Plaintiffs proved work at the factory was a significant causal factor in development
    of the alleged asbestosis.            The Commission has not, of course, made this
    determination16—but will do so if required by this Court’s resolution of the bellwether
    cases and factual circumstances particular to the remaining Consolidated Plaintiffs.
    The Commission also determined that, with respect to employment at the factory,
    neither colon cancer nor tonsil cancer were occupational diseases pursuant to
    N.C.G.S. § 97-53(13).
    D. The Bellwether Plaintiffs’ Claims
    Plaintiffs and Defendant presented weeks of expert testimony concerning the
    common issue of whether Plaintiffs could have been subjected to sufficient airborne
    asbestos—chrysotile or amphibole—while working at the factory to cause
    compensable asbestosis. 
    James, 160 N.C. App. at 562
    , 586 S.E.2d at 560. Evidence
    15  I.e., that any alleged asbestos-related disease could not have “arisen out of” employment
    with Defendant. 
    Gallimore, 292 N.C. at 402
    03, 233 S.E.2d at 531
    –32; N.C.G.S. § 97-54.
    16 Except for the five Bellwether Plaintiffs currently before us. Because these five cases were
    actually tried, the Commission considered the evidence relevant to the “common issues,” as well as the
    evidence uniquely relevant to each individual Bellwether Plaintiff.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    was also presented for Bellwether Plaintiffs’ individual claims, including evidence
    related to whether Bellwether Plaintiffs had the diseases alleged. Based upon this
    testimony, deposition testimony, and the exhibits tendered, the Commission
    determined that Plaintiffs failed to meet their burdens on all accounts.
    IV. Plaintiffs’ Common Issues Arguments
    Plaintiffs did not brief the common issues separately from the individual
    issues, so we look to Bellwether Plaintiffs’ individual briefs for the common issues
    arguments. Because our analysis pertaining to the common issues will apply to the
    claims of all Consolidated Plaintiffs—not just Plaintiff Hinson or the other Bellwether
    Plaintiffs—where Plaintiff Hinson’s brief refers to “Plaintiff,” we will substitute
    “Plaintiffs” or “Consolidated Plaintiffs,” which will refer to all Consolidated Plaintiffs.
    Generally, Plaintiffs argue: (A) The Commission did not apply the appropriate
    burden of proof in reaching its determinations concerning Plaintiffs’ exposure to
    asbestos as employees in the factory; (B) the Commission relied on incompetent
    evidence in reaching its conclusions; (C) certain of the findings of fact were not
    supported by sufficient competent evidence; and (D) the ultimate findings/conclusions
    of law are incorrect.
    A. Burden of Proof
    Plaintiffs first argue that the Commission “placed an impermissible burden of
    establishing the amount of exposure to asbestos” on Plaintiffs. We disagree.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    As a general matter: “The employee seeking workers’ compensation benefits
    bears the burden of proving every element of compensability. The degree of proof
    required of a claimant under the Act is the ‘greater weight’ or ‘preponderance’ of the
    evidence.” Hardin, 136 N.C. App. at 
    354, 524 S.E.2d at 371
    (citations omitted).
    Plaintiffs specifically argue:
    One of the critical issues in the [consolidated cases] was
    whether Plaintiff[s] [were] exposed to asbestos and
    whether such exposure was medically capable of causing a
    disease. . . . .
    [The] Commission made findings and conclusions
    regarding the amount of exposure [] Plaintiff[s] had to
    asbestos and whether that level was sufficient to cause a
    disease.
    The Commission specifically, and repeatedly, [determined]
    that [Plaintiffs] “[were] not exposed to asbestos in such
    form and quantity, and used with such frequency, as to
    cause asbestosis or any asbestos-related condition.” What
    the . . . Commission . . . did was place the burden on []
    [Plaintiffs] to establish the level of exposure to [asbestos].
    Under North Carolina law, that is impermissible.
    We first note that Plaintiffs’ counsel acknowledged during the hearings that
    Plaintiffs’ burden was to prove “what [Plaintiffs’] actual exposures were” to asbestos
    “[a]t the plant.” In addition, Plaintiffs have not challenged finding of fact 2, which
    states in part: “Plaintiffs allege that they were exposed to asbestos [while working in
    the factory] in such form and quantity and with such frequency that it caused
    asbestosis.” As we must take this unchallenged finding as correct, Plaintiffs now
    challenge the application of a standard they approved while arguing before the
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    Commission.     Nonetheless, Plaintiffs contend that the Commission erroneously
    applied the following burden of proof contained in N.C.G.S. § 97-53—and that by so
    doing, the Commission imposed upon Plaintiffs the impermissible burden of
    “establish[ing] the[ir] level[s] of exposure” to asbestos. N.C.G.S. § 97-53 contains
    different requirements depending on the type of injury alleged, including the
    following:
    Occupational diseases caused by chemicals shall be
    deemed to be due to exposure of an employee to the
    chemicals herein mentioned only when as a part of the
    employment such employee is exposed to such chemicals in
    such form and quantity, and used with such frequency as
    to cause the occupational disease mentioned in connection
    with such chemicals.
    N.C.G.S. § 97-53. Defendant’s counsel referred to this section of N.C.G.S. § 97-53 in
    the opening statement to the deputy commissioner, and Plaintiffs did not object. On
    appeal, Plaintiffs do not specifically challenge the applicability of this part of N.C.G.S.
    § 97-53 to cases involving exposure to asbestos—but do state that “this language
    speaks of ‘chemicals’ and not necessarily asbestos.         There was no testimony or
    evidence that asbestos would be considered a ‘chemical’ under the statute.” Plaintiffs
    further contend: “Regardless, this statute, as applied by the Commission, would be in
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    direct conflict with . . . case law whereby [employees were] not required to establish
    the amount of exposure.”17
    We note that this part of N.C.G.S. § 97-53, by its plain language, only applies
    to “[o]ccupational diseases caused by chemicals” “herein mentioned[,]” and only to
    “occupational disease[s] mentioned in connection with such chemicals.” N.C.G.S. §
    97-53.        Even assuming that asbestos would be considered a “chemical” for the
    purposes of this section, asbestos is not “mentioned” in N.C.G.S. § 97-53, and
    asbestosis is not “mentioned in connection with” asbestos, or any other “chemical.”
    Id.; cf., e.g. N.C.G.S. § 97-53(24) and (12) (compare “[a]sbestosis” to “[p]oisoning by
    benzol, or by nitro and amido derivatives of benzol”).
    However, the Commission did include language that tracks the language of
    this part of N.C.G.S. § 97-53 in five of its ultimate findings. For example, finding 45
    states in part: “The greater weight of the evidence in view of the entire record does
    not show that [P]laintiffs, through their employment at [the] factory, were exposed to
    asbestos in such form and quantity and [] with such frequency as to cause or
    significantly contribute to the development of asbestosis[.]” (Emphasis added). The
    italicized portion of this ultimate finding tracks the language of N.C.G.S. § 97-53.
    17While this Court is generally bound by its prior decisions interpreting a statute, In re Civil
    Penalty, 
    324 N.C. 373
    , 384, 
    379 S.E.2d 30
    , 37 (1989), no such interpretation of this part of N.C.G.S. §
    97-53 has occurred. Since there are no appellate opinions interpreting N.C.G.S. § 97-53 in the manner
    suggested by Plaintiffs, this Court is bound by the language of the statute itself, not the principles of
    law discussed in the two cases cited by Plaintiffs—one of which is unpublished—that do not address
    this provision.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    However, though the underlined portion is not found in N.C.G.S. § 97-53, it does
    correspond with the correct burden for proving a causal connection between a
    particular employment and alleged asbestosis. “Asbestosis may be [a compensable]
    occupational disease provided that the worker’s exposure to . . . [asbestos]
    ‘significantly contributed to, or was a significant causal factor in,’ the development of
    the disease.” Patton v. Sears Roebuck & Co., 
    239 N.C. App. 370
    , 375, 
    768 S.E.2d 351
    ,
    355 (2015) (citations omitted) (emphasis added).
    As discussed below, we find that the burden applied by the Commission was a
    correct application of the law to the facts of the consolidated cases. The testimony of
    both Plaintiffs’ and Defendant’s experts included opinions that support the
    Commission’s focus on “exposure to airborne asbestos,” “in such form,” in sufficient
    “quantity,” and “with such frequency”—i.e. recurring exposures over time, or duration
    of exposure—in making its determination of whether Plaintiffs had met their burden
    of proving a causal connection between their alleged asbestosis and their work at the
    factory. These categories conform with factors enumerated by the NCI concerning
    elevated risk for asbestos-related diseases: “Dose (how much asbestos an individual
    was exposed to)[; d]uration (how long an individual was exposed)[; and s]ize, shape,
    and chemical makeup of the asbestos fibers.”          NCI Fact Sheet at 2-3 (citations
    omitted).   They also conform to one of the non-exclusive circumstantial factors
    appropriate for consideration in determining whether a plaintiff has met the burden
    of proving a causal relationship: “[T]he extent of exposure to the disease or disease-
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    causing agents during employment[.]” 
    Booker, 297 N.C. at 476
    , 256 S.E.2d at 200
    (citations omitted). Therefore, consideration of these factors was appropriate in
    determining whether asbestos exposure at the factory “‘was a significant causal factor
    in,’ the development of” Plaintiffs’ alleged asbestosis. 
    Id. (citations omitted).
    1. “Form” of Asbestos
    As recognized by the NCI, the “size, shape, and chemical makeup of the
    asbestos fibers” are relevant in determining the likelihood exposure will result in
    disease. NCI Fact Sheet at 2-3 (citations omitted). Plaintiffs’ “expert in electron
    microscopy and lung tissue analysis,” Mark Wilson Rigler, PhD (“Rigler”),18 agreed
    with the NCI Fact Sheet that “asbestiform minerals come in a couple of different
    broad classes”—“serpentine,” which “is mainly comprised of chrysotile” asbestos and
    is “like a tube[,]” and “amphibole,” which is “mainly composed of blocky structural
    forms.” Rigler clarified that only when these minerals are in fiber form are they
    capable of causing disease. Rigler testified that “probably ninety-five percent of the
    products [] manufactured, at least in America, had chrysotile asbestos[,]” “and the
    other five percent would’ve probably had amosite [an amphibole form], and that
    might’ve been pipe coverings, that kind of thing.”
    Rigler further testified that the human body handles chrysotile asbestos
    differently than amphibole asbestos:
    18 Because Plaintiffs argue on appeal that only medical experts are qualified to give certain
    causation opinion testimony, in order to avoid confusion concerning which experts were medical
    doctors and which were PhDs, we will only use the honorific “Dr.” when referring to medical doctors.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    Chrysotile asbestos, which is the tubular type that we
    talked [about] earlier, . . . is not retained as long as the
    amphibole fibers are, so if you get chrysotile in the lung, it
    tends to move that out a bit quicker. Some of the
    [chrysotile] fibers are smaller. They are taken up a little
    bit easier into macrophages. . . . . So . . . then they try to
    move out, if they can, through your lymphatic circulation.
    Some are removed out through the blood stream, but they
    do . . . migrate in the body. Now, the amphibole types of
    asbestos, they tend not to migrate like that. They tend to
    stay in the body for 45 [years], so you can, you know, after
    ten, twenty, thirty years, you can see amphibole asbestos
    in the body.
    Defendant’s expert, Dr. Victor Roggli (“Dr. Roggli”), testified that chrysotile asbestos
    fibers cleared from the body much more rapidly than amphibole fibers. Plaintiffs’
    expert industrial hygienist, William M. Ewing (“Ewing”), agreed that amosite
    asbestos is “recognized as being more potent when it comes to cancer and exposure”
    than chrysotile asbestos, but testified that he did not know if “there is a general
    understanding among [other] industrial hygienists . . . that chrysotile is less potent
    with respect to asbestosis as well[.]” Dr. Roggli testified that exposure to commercial
    amphibole fibers can cause disease at a lower dosage than other asbestos fibers, such
    as chrysotile. He stated the difference was very significant for lung cancer, and that
    “it’s believed” by many experts that someone would require a greater exposure to
    “chrysotile to get to asbestosis than for commercial amphiboles.” Dr. Roggli testified
    that chrysotile asbestos fibers do not “form asbestos bodies as well” as amphibole
    asbestos fibers, and that “it really takes huge amounts of exposure to chrysotile to get
    asbestosis.” Dr. Thomas Sporn (“Dr. Sporn”) testified: “In general my opinions have
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    been that exposure [to] chrysotile containing end products [commercial products such
    as insulation, gaskets, or brakes] do not particularly cause . . . asbestosis[.]”19
    According to Dr. Roggli, asbestos fibers less than five microns in length “would
    not be disease-producing[,]” and that approximately ninety percent of the scientific
    community was of the same opinion. In prior testimony, Rigler also defined “larger
    structures” indicative of occupational exposure as “greater than five microns.” Dr.
    Roggli testified that chrysotile fibers of over five microns are rarely found in lungs—
    estimating that only about ten percent of chrysotile lung exposures include fibers
    longer than five microns. Rigler testified that “asbestos bodies” are created when
    tissue forms around an asbestos fiber, and they can be indicators of asbestosis.
    Defendant’s expert, Dr. Timothy David Oury (“Dr. Oury”), testified: “without asbestos
    bodies, [you cannot] make the pathological diagnosis for asbestosis[.]” Because of its
    generally smaller size, and the rapidity with which the human body evacuates it, Dr.
    Roggli testified that “of the asbestos types,” chrysotile is “the least effective at forming
    asbestos bodies.”
    Dr. Roggli’s expert medical opinion was that “short fibers of chrysotile[20 are]
    more consistent with a background environmental exposure than a long fiber would
    be[.]” Dr. Roggli testified that short chrysotile fibers are commonly found in water
    supplies and products such as beer, wine, soft-drinks, and ketchup. Rigler testified
    19   Assuming the product contained only chrysotile asbestos.
    20   Less than five microns.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    that multiple governmental and science agencies required that a suspected asbestos
    fiber had to be at least five microns in length “in order to be counted as a fiber” for
    purposes of determining asbestos exposure—but stated that he disagreed with this
    requirement.21 Rigler testified that a relatively small amount of short chrysotile
    fibers found in lung tissue would suggest a very significant prior exposure to
    chrysotile. Rigler saw no contradiction between his testimony in the present cases
    and testimony he had given in prior cases that “‘[t]ypically [a]n occupational exposure
    will be indicated by longer fibril structures.’” “‘As far as the length of structures, you
    will not normally see [fibers longer than five microns] in non-occupational exposure.
    You may see some much, much smaller structures. That’s typically what you see in
    environmental type exposure.’”
    Dr. Roggli testified in response to the idea that finding short chrysotile
    asbestos fibers in lung tissue was indicative of a substantial prior occupational
    exposure to chrysotile asbestos with the following: “Well, if that’s the case, it means
    everybody in the general population has had a huge exposure to chrysotile in the past
    because that’s exactly what you find in lung tissue from the people from the general
    population—is a number of short chrysotile fibers.”
    The Commission found as fact: “Chrysotile is a type of asbestos, often shorter
    than five micro[ns], that is particularly susceptible to being broken down quickly in
    21  There are also minimum width requirements, and the structure must also “have an aspect
    ratio of three . . . to one.”
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    acidic environments, such as a human lung.” “Fibers shorter than 5 micro[ns], due
    to their length, are cleared quickly by the lungs and are not believed to contribute to
    [asbestosis].”    “Many experts believe that chrysotile asbestos does not cause or
    contribute to asbestosis or asbestos-related disease due to its short clearance half-life
    and the fact that persistence of a fiber within the lung is a crucial determinant of its
    pathogenicity.”      There was plenary evidence from which the Commission could
    determine that the “form” of the asbestos that Plaintiffs alleged they were exposed to
    at the factory was a relevant factor in determining whether Plaintiffs’ alleged
    asbestos exposure at the factory could have caused asbestosis.
    2. Quantity
    The quantity, or amount of asbestos exposure, was central to the Commission’s
    determination.       The NCI refers to this as the “dose,” “how much asbestos an
    individual was exposed to[,]” and considers it an important factor to consider. NCI
    Fact Sheet at 3 (citations omitted). There are two general ways in which the amount
    of exposure impacts the Commission’s causation analysis: (1) Was the exposure
    sufficient to be a “significant causal factor” in the development of Plaintiffs’ alleged
    asbestosis; and (2) was the exposure “significantly greater” than the background
    environmental exposure.22 “[T]he ‘causative danger must be peculiar to the work and
    22 “Significant means ‘having or likely to have influence or effect: deserving to be considered:
    important, weighty, notable.’ Significant is to be contrasted with negligible, unimportant, present but
    not worthy of note, miniscule, or of little moment.” 
    Rutledge, 308 N.C. at 101
    –02, 301 S.E.2d at 370
    (citation omitted). Proving what constituted exposure “significantly greater” than environmental
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    not common to the neighborhood.’” 
    Culpepper, 93 N.C. App. at 248
    , 377 S.E.2d at 781
    (citation omitted). If the answer to either of these questions was “no,” then any
    alleged asbestos-related diseases could not be causally linked to work at the factory.
    Rigler testified that at his laboratory, in order to estimate the amount of
    exposure, they conduct a fiber analysis using “grid counting”; “we’ll count the number
    of asbestos [fibers].” According to Rigler, grid counting is “standard protocol.” Rigler
    testified that he would first use an electron microscope to count “what we call large
    fiber structures, ones that are larger than five microns or so.” Then Rigler increases
    magnification to the extent that he can count asbestos fibers “a half micron in size
    and up.” An estimated number of fibers per gram of lung tissue is extrapolated from
    the number of fibers actually detected in a smaller amount of tissue.
    Although Rigler testified that he believed “background” exposure levels should
    be zero, he testified in 2000 that, based on his own research and the relevant
    literature, the environmental background range he had seen had “‘been upwards of
    two hundred and fifty thousand [asbestos fibers] [per gram of lung tissue].
    Sometimes, again, it depends on the literature that you look at—half a million
    structures.’” Rigler admitted that he used to compare the number of structures per
    gram against a cohort, or control group, developed from examining lung tissue of
    people with no reported occupational asbestos exposure. The range of structures per
    exposure for these cases was Plaintiffs’ burden, and a determination that could only be made by the
    Commission—absent consensus between the parties.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    gram determined from the cohort constituted the range of non-occupational
    background environmental asbestos exposure of the general population.                    Rigler
    stopped comparing tissue samples examined in his lab against a cohort before his
    examination of Plaintiff Jones’23 lung tissue sample, which Rigler opined showed
    asbestosis. Dr. Roggli testified that the number of structures counted is meaningless
    without a proper cohort to compare that number to.
    The deputy commissioner questioned the basis of Rigler’s opinion that any
    amount of asbestos fibers found in lung tissue would be indicative of occupational
    exposure, and Rigler’s opinion that the amount of asbestos found in Plaintiff Jones’
    tissue indicated asbestosis:
    THE COURT: The [Plaintiffs] I’m looking at are from
    Charlotte, . . . which is a major metropolitan area[.] So I
    would assume that you would expect that some people
    within the Charlotte area, who’ve never had an
    occupational history, would have some asbestos in their
    lungs.
    [RIGLER]: I don’t know.
    THE COURT: Don’t know. Wow.
    Rigler then testified: “I think that you’re going to see a lot of variation [in background
    level] depending upon where these people lived. It’s always going to be dependent
    upon what they did and where they lived.” Plaintiffs’ expert, Dr. David A. Schwartz,
    23   One of the deceased Consolidated Plaintiffs whose lung tissue was examined.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    testified “I don’t think people in the general public are at risk of developing asbestosis
    based on their exposures to environmental concentrations of asbestos.”
    Dr. Roggli testified: “The analysis that we did did not demonstrate that
    [Plaintiff Jones] was exposed to asbestos greater than that of [the] general
    population.” Dr. Roggli explained that the types of employment that could expose a
    worker to the levels of chrysotile asbestos required to cause asbestosis were those jobs
    where employees were working directly with the asbestos, such as “insulators,”
    “shipyard workers,” and specialized work within other industries, but he could not
    remember ever diagnosing a tire factory employee with asbestosis.
    Therefore, there was evidence presented that most of the asbestos used in the
    factory was chrysotile, and that Plaintiffs would have had to have been exposed to
    “huge amounts” of it to develop asbestosis. Based on the evidence, the Commission
    needed to determine whether working at the factory exposed Plaintiffs to “quantities”
    of asbestos fibers sufficient to cause asbestosis, and whether working at the factory
    exposed Plaintiffs to quantities of asbestos “significantly” greater than the
    background levels to which the general public were exposed.
    3. Frequency
    Plaintiffs’ experts and Defendant’s experts disagreed concerning the likelihood
    that episodic exposures to elevated levels of asbestos were likely to cause asbestosis.
    The   Commission     found:   “Asbestos-related     diseases   follow   a   dose-response
    relationship—the higher the cumulative exposure dose, the greater the risk of
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    disease, with asbestosis generally requiring the highest dose.” The NCI Fact Sheet
    included “duration”—“how long an individual was exposed” to airborne asbestos
    fibers—as one of the factors to consider when evaluating the risks of developing
    asbestos-related diseases. NCI Fact Sheet at 3 (citations omitted). It is the position
    of the NCI that though “it is clear that the health risks from asbestos exposure
    increase with heavier exposure and longer exposure times, investigators have found
    asbestos-related diseases in individuals with only brief exposures.” 
    Id. It was
    the
    province of the Commission to determine from the record evidence if Plaintiffs had
    met their burden of proving sufficient frequency of exposure—whether by proving
    large, intermittent exposures, or lesser but more continuous exposures.
    Plaintiffs’ expert, Ewing, testified concerning the relationship between
    “quantity,” “frequency,” and duration of asbestos exposure: “You would like to have
    exposure information [quantity], duration information, how long is that exposure
    going on, and then frequency information, so you’d like to have those three pieces of
    data. If you have that, then you can do some calculations that can give you a person’s
    dose.” Ewing agreed that for the Bellwether Plaintiffs, “at most, their exposures were
    episodic[.]” Defendant’s expert, Dr. Andrew J. Ghio (“Dr. Ghio”), testified that, in his
    expert medical opinion, he did not believe “an individual working at [the factory]
    [wa]s at increased risk for asbestosis.” The Commission noted: “Dr. Roggli testified
    that there was not sufficient exposure to asbestos at the factory in question to
    contribute to or to cause an asbestos-related disease for Mr. Jones or anyone in his
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    position.” Drs. Ghio and Roggli were both of the opinion that Plaintiffs would have
    only endured minor, infrequent episodic exposures to airborne asbestos fibers, and
    these minor episodic exposures would not have been significant enough to increase
    Plaintiffs’ risks of developing asbestos-related diseases. The Commission did not err
    in considering the “frequency” of Plaintiffs’ exposure to airborne asbestos fibers.
    4. Last Injurious Exposure
    Plaintiffs   make    no    arguments      on   appeal   concerning   the   liability
    determinations made by the Commission pursuant to N.C.G.S. § 97-57. Therefore,
    any such arguments are deemed abandoned. Although, as discussed above, the
    Commission was not required to make any determination pursuant to N.C.G.S. § 97-
    57—once it determined that Plaintiffs had failed to prove their alleged asbestosis
    arose out of their employment, and was therefore not compensable—the Commission
    did make this determination in its ultimate findings 16, 19, 21, 23, 43 and 45.
    For example, in ultimate finding 43 the Commission determined that Plaintiffs
    had not been “exposed to the hazards of asbestosis through [their] employment with
    [D]efendant for 30 days or parts thereof within a seven-month consecutive period
    which proximately augmented the disease process of asbestosis to the slightest
    degree.” That unchallenged determination relieved Defendant of any liability for
    Plaintiffs’ alleged asbestosis—even assuming, arguendo, that all Plaintiffs had
    asbestosis, and that their asbestosis was compensable. This is because the “last
    injurious exposure” analysis is only concerned with which employer—or insurance
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    company—will be held liable for a proven compensable occupational disease. See
    Penegar, __ N.C. App. at __, 815 S.E.2d at 398.
    5. Conclusion
    It was the province of the Commission to decide, based on competent evidence,
    what factors Plaintiffs needed to prove in order to meet the burden of proving asbestos
    exposure at the factory was a significant causal factor in the development of their
    alleged asbestosis. Based on the evidence presented, the “form” of the asbestos, and
    the “quantity” and “frequency” of exposure, were legitimate considerations in making
    this determination. Therefore, the Commission’s ultimate findings that state “[t]he
    greater weight of the evidence in view of the entire record shows that [P]laintiffs were
    [not] exposed to airborne asbestos . . . in such form and quantity and with such
    frequency as to cause . . . asbestosis” do not show that the Commission “placed an
    impermissible burden” on Plaintiffs.
    In addition, the Commission also made the following ultimate finding in
    finding 43:
    Given the evidence of air contaminant measurements
    taken at [the] factory, the pathology evidence collected
    from workers’ lungs, and the scientific and epidemiological
    literature presented on the subject, the greater weight of
    the evidence in view of the entire record does not
    demonstrate a causal connection between asbestosis and
    employment at the . . . factory.
    This ultimate finding—which determined Plaintiffs failed to prove the required
    causal connection, 
    Patton, 239 N.C. App. at 375
    , 768 S.E.2d at 355, and other
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    authority cited—does not contain the language to which Plaintiffs object. Finally, the
    Commission’s unchallenged determinations pursuant to N.C.G.S. § 97-57 serve to
    relieve Defendant from any liability for Consolidated Plaintiffs’ alleged compensable
    asbestosis. This argument is without merit.
    B. Competent Evidence
    We have held that Defendant cannot be held liable for Plaintiffs’ alleged
    asbestosis, even were it compensable, due to the Commission’s unchallenged N.C.G.S.
    § 97-57 determinations. However, in light of the number of Consolidated Plaintiffs
    impacted by this opinion, we address Plaintiffs’ remaining arguments. Plaintiffs
    primarily argue that certain evidence relied upon by the Commission was not
    competent. However, as this Court has stated:
    Although [Plaintiffs] point[] to . . . evidence which [they]
    feel[] was incompetent to support [some of] the
    . . . Commission’s findings of fact, we find it unnecessary to
    decide those points of contention in light of the rule that
    findings of fact which are supported by competent evidence
    are conclusive on appeal, even though other incompetent
    evidence may have been improperly admitted.
    
    Kennedy, 101 N.C. App. at 33
    , 398 S.E.2d at 682 (citation omitted) (emphasis added).
    Therefore, even assuming, arguendo, the Commission relied upon some incompetent
    evidence, our review is limited to whether the competent evidence was sufficient to
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    support the Commission’s findings of fact—including its ultimate findings—and
    whether the findings support its conclusions and rulings.24 
    Id. Plaintiffs’ arguments
    fall into the following general categories: (1) The “air
    sampling” evidence and the “fiber year theory”; (2) reliance on “non-medical” expert
    testimony; (3) reliance on the lung pathology from the five deceased Plaintiffs; and
    (4) the Commission’s reliance on the above allegedly incompetent evidence in support
    of its ultimate findings and conclusions.
    1. Air Sampling and Fiber Year Theory
    Plaintiffs argue that “the Commission erred in relying on the ‘fiber year
    theory’” and air sampling to determine that Plaintiffs were not exposed to sufficient
    amounts of airborne asbestos at the factory to cause asbestosis. We disagree.
    Specifically, Plaintiffs argue that the “Commission never stated what level of
    exposure was necessary to cause a disease except to subscribe to [D]efendant’s usage
    of the ‘fiber year theory.’” Plaintiffs further argue that Defendant “could not prove
    the amount of [Plaintiffs’] exposure to asbestos and could only provide a very broad
    guess at the level necessary to cause a disease.”               Plaintiffs also argue that the
    Commission ignored the fact that incidents of airborne asbestos being released in the
    factory were “occasional,” not constant, and, therefore, “no one knows how much
    24  Plaintiffs did not seek to suppress the evidence they now challenge on appeal—either prior
    to or during the hearings. Although hearings before the Commission are quasi-judicial, this Court has
    applied N.C.G.S. § 8C–1, Rule 702 in its review of workers’ compensation claims. Wise v. Alcoa, Inc.,
    
    231 N.C. App. 159
    , 
    752 S.E.2d 172
    (2013).
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    asbestos was being damaged on any particular day. No one knows how much asbestos
    was inhaled by [Plaintiffs]. The only evidence of the levels of the asbestos in the air
    was from air sampling done in the facility.”
    Plaintiffs may be correct that “[n]o one knows how much asbestos was inhaled
    by” Plaintiffs, but it was Plaintiffs’ burden to prove that their alleged exposure to
    asbestos fibers at the factory caused or significantly contributed to their alleged
    asbestos-related diseases. The fact the Commission did not include findings of fact
    related to all the evidence that Plaintiffs believe supported their claims does not mean
    the Commission ignored this evidence. “[T]he Commission does not have to explain
    its findings of fact by attempting to distinguish which evidence or witnesses it finds
    credible.” Deese v. Champion Int’l Corp., 
    352 N.C. 109
    , 116, 
    530 S.E.2d 549
    , 553
    (2000) (citation omitted).   “Requiring the Commission to explain its credibility
    determinations . . . would be inconsistent with our legal system’s tradition of not
    requiring the fact finder to explain why he or she believes one witness over another
    or believes one piece of evidence is more credible than another.” 
    Id. at 116-17,
    530
    S.E.2d at 553. Further, the Commission stated that it had “reviewed and considered
    all hearing and deposition transcripts, along with all evidentiary exhibits,
    arguments, and briefs in reaching a decision[.]” The opinion and award contains over
    25 pages devoted to listing the transcripts, depositions, and exhibits considered by
    the Commission. The Commission also stated multiple times throughout the opinion
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    and award that its determinations were based upon the “greater weight of the
    evidence in view of the entire record[.]”
    Plaintiffs continue: “Yet the Commission found that [Plaintiffs were] not
    exposed to . . . levels” of asbestos sufficient to cause asbestosis.   Plaintiffs again
    suggest that it was Defendant’s burden to disprove Plaintiffs’ claims when it was
    Plaintiffs’ burden to prove all the elements necessary to show compensable asbestos-
    related diseases. Further, Plaintiffs did not direct this Court to any part of the
    Commission’s opinion and award in which the Commission “found that [Plaintiffs
    were] not exposed to” sufficient “fiber years” of asbestos to cause asbestosis. This is
    because “fiber years” are not discussed in the opinion and award. There is no evidence
    that the Commission subscribed to the fiber year theory, or relied on it when making
    its relevant findings and conclusions.
    Plaintiffs argue: “There was no evidence introduced by [D]efendant to establish
    whether [P]laintiffs’ exposure was consistent with the background level of the
    [factory]. There was no evidence introduced showing the levels of exposure when
    [P]laintiff[s] w[ere] damaging insulation, using compressed air on damaged
    insulation or cutting asbestos gaskets.” It was Plaintiffs’ burden to introduce this
    evidence, and Defendant had no burden to convince the Commission that Plaintiffs’
    alleged injuries did not arise in the course of employment at the factory.
    Although Plaintiffs presented evidence to the contrary, there was plenary
    evidence—including evidence unrelated to air sampling or the fiber year theory—to
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    support the Commission’s ultimate finding that Plaintiffs were not—due to their
    work at the factory—exposed to asbestos sufficient to cause asbestosis. For example,
    Dr. Ghio testified as follows:
    [DR. GHIO]: Again, the only [air sampling] levels that I’m
    aware of are those taken during the health hazard
    evaluation done by NIOSH in their review of the plants
    across the Midwest[.] . . . . And the ones that [Defendant’s
    attorneys] forwarded to me regarding [the factory]. This is
    outside of my expertise though. I’m not an industrial
    hygienist. I’m a pulmonologist.
    ....
    Q. Sir, do you think it’s proper for you to make an
    attribution of cause and effect when you acknowledge that
    you’re unaware of any of the exposure levels for disease in
    the tire industries?
    A. I’m aware of the levels at [the factory]. They were
    forwarded to me. Regarding a more global approach to that
    question, you know, can a physician be called upon to make
    a diagnosis of asbestosis without being aware of the actual
    dust levels in the environment, and it’s very rare that, as
    pulmonologists . . . we’re made [aware of] those values. We
    make diagnoses all the time of asbestosis. 99 percent of all
    diagnoses of asbestos[is] are made without any awareness
    of such levels. Dr. Ohar and Dr. Schwartz [Plaintiffs’
    medical experts] were unaware of levels when they
    diagnosed these patients to have asbestosis.
    Dr. Ghio’s testimony shows he was not, to any significant degree, “relying on the ‘fiber
    year theory’” or the air sampling in order to reach his conclusions. Further, as noted
    in finding of fact 38: “Dr. Roggli testified that there was not sufficient exposure to
    asbestos at the factory in question to contribute to or to cause an asbestos-related
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    disease for Mr. Jones or anyone in his position.” This opinion was not based air
    sampling from the factory.
    Dr. Ghio also testified: “[Asbestos] was simply there [in the factory], and by
    being there, [Plaintiffs] misinterpret that to [mean] that they’re at increased risk.
    They’re aware that piping in [the factory] had asbestos, and they have—they have
    the misconception that that increases their risk for asbestosis, and it does not.”
    Plaintiff’s expert, Ewing, agreed with Dr. Ghio in this regard, stating: “I’m not of the
    opinion that because pipe insulation is present there must be exposure. There has to
    be work going on on the pipe insulation or some disturbance of that material for the
    exposure to arise.” In forming his opinions, Dr. Ghio relied heavily on Plaintiffs’
    patient histories, and review of their x-rays:
    [PLAINTIFFS’ COUNSEL:] Dr., with respect to exposure
    history, you’ve testified in the past, have you not, that you
    put more emphasis on what the patient says than you do
    actually specific [airborne] fiber levels, sir. Do you
    remember that testimony?
    A. I do. I follow the ATS [(“American Thoracic Society”)]
    criteria which is—I base my diagnosis whenever possible
    on an accurate occupation history.
    Q. All right. So in the case of [Plaintiffs], you really never
    looked at what the industrial hygiene reported as to what
    the individual exposures were or the sampling was. Is that
    not true, sir?
    A. I have been provided actual values of fiber
    measurements, and actual fiber values of fiber
    measurements were in agreement with the histories, and
    that is that the exposure was minimal.
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    Q. Well, let me ask you, sir. [W]hen you gave your report
    and had your opinions about [Plaintiffs], you did not at any
    time mention the fiber levels. Did you, sir, or the industrial
    hygiene results?
    A. I don’t believe I did.
    Q. All right. And you’ve testified repeatedly . . . that
    patient histories are the best indicator of exposures, even
    over specific fiber levels. Has that been your testimony,
    sir?
    A. Well, it’s very rare for me to get . . . specific fiber levels.
    So, yes, that has been my testimony in the past. And as a
    physician, we take occupational histories. That’s what we
    do.
    ....
    Q. Sir, . . . you do require an occupational environmental
    history, but you go along to also require that the industry
    and occupation place the patient at an increased risk. And
    also, you require a marker of exposure, usually pleural
    plaque, sir. Do you see that?
    A. I don’t require all three. I require an occupational, and
    environmental history that increases the patient’s risk for
    asbestosis or I need a marker of exposure. If I see pleural
    plaques that are bilateral, I assume that that individual is
    at an increased risk.
    THE COURT: And that’s the marker.
    [DR. GHIO]: That’s the marker. You know, if that person
    has had enough fiber, you know, even though [their
    occupation is] lower in the pyramid, it’s way down at the
    bottom, I assume, you know, they had bilateral plaques,
    I’m going to give them the benefit of the doubt they had the
    exposure.
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    THE COURT: And you, in looking at all the x-rays from
    [Plaintiffs], you didn’t see anything that was a marker in
    any of them.
    [DR. GHIO]: Not a single one.
    Dr. Ghio stated that his opinions were based on the following:
    [DR. GHIO]: [T]he tire industry has never been reported in
    the medical literature to be associated with asbestosis. I’ve
    looked at the industrial hygiene behind the exposures of
    [the factory], and forty years would not make the criteria
    of twenty-five fiber years. I’ve been looking at a lot of these
    chest x-rays. I’ve not seen any evidence of asbestosis. I’m
    not seeing any evidence for even those diseases that
    require very, very minute exposures to fibers, and those
    would be pleural plaques. I don’t see any evidence of a
    significant exposure. So I think because of . . . all the above,
    I don’t think an individual working at [the factory] is at
    increased risk for asbestosis. [Emphasis added].
    To the extent that the Commission relied on the air sampling results as
    consistent with the testimony of Defendant’s experts that asbestos exposure at
    Defendant’s plant would not be sufficient to cause Plaintiffs’ alleged asbestosis,
    because the air sampling reports never indicated significantly elevated levels of dust
    or asbestos fibers, the Commission did not err in considering that evidence. Had the
    air sampling results shown elevated levels of asbestos during the testing periods, that
    would have been relevant evidence favorable to Plaintiffs that the Commission would
    have properly considered. The fact that none of the air sampling indicated elevated
    asbestos levels does not alter the relevance of the evidence, nor render it
    incompetent—it simply tends to support Defendant’s position more than Plaintiffs’.
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    It was for the Commission to determine the weight to give to that evidence, and
    Plaintiffs fail to demonstrate that the Commission abused its discretion in that
    regard. See 
    Wise, 231 N.C. App. at 164
    , 752 S.E.2d at 175–76. This argument is
    without merit.
    2. Medical Expert Evidence
    Plaintiffs argue that “the Commission erred by relying only on non-medical
    expert testimony” because “the amount of exposure necessary to cause disease is a
    medical question [that] only a physician can answer.” We disagree.
    Plaintiffs contend that there was “insufficient medical expert testimony for the
    Commission to determine that [Plaintiffs were] not exposed to sufficient levels of
    asbestosis to cause a disease.” Again, it was Plaintiffs’ burden to present evidence,
    medical or otherwise, to prove sufficient exposure to asbestos—not Defendant’s
    burden to prove insufficient exposure.       Plaintiffs bore the burden of producing
    “competent evidence to support the inference that the [exposure] in question resulted
    in the injury complained of[.]” Click v. Freight Carriers, 
    300 N.C. 164
    , 167, 
    265 S.E.2d 389
    , 391 (1980). Plaintiffs rely in part on Click in support of their argument. Click
    states:
    The quantum and quality of the evidence required to
    establish prima facie the causal relationship will of course
    vary with the complexity of the injury itself. There will be
    “many instances in which the facts in evidence are such
    that any layman of average intelligence and experience
    would know what caused the injuries complained of.” On
    the other hand, where the exact nature and probable
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    genesis of a particular type of injury involves complicated
    medical questions far removed from the ordinary
    experience and knowledge of laymen, only an expert can
    give competent opinion evidence as to the cause of the
    injury.
    
    Id. (citations omitted).
    Click was not an asbestosis case, and the injury involved in
    Click required very different causation evidence. Each case is fact specific, and
    Plaintiffs cite to no authority that would per se exclude reliance on non-medical expert
    testimony when deciding whether a particular employment could have caused or
    contributed to development of an asbestos-related disease.25
    In asbestosis cases, diagnosis of the disease itself requires expert medical
    testimony. However, once asbestosis is established, expert medical testimony is not
    necessarily required to establish a causal connection between the disease and the
    worker’s employment. For example, if a plaintiff has been diagnosed with asbestosis,
    non-medical evidence that the only place the plaintiff was exposed to asbestos was
    while working for the defendant-employer should be sufficient to prove a causal
    connection. This Court has reasoned: “If a plaintiff has not been exposed in prior
    employment, and has asbestosis, then that could give rise to an inference that he was
    exposed (and last injuriously exposed) while working for defendant-employer.”
    Vaughn v. Insulating Servs., 
    165 N.C. App. 469
    , 474, 
    598 S.E.2d 629
    , 632 (2004).
    Conversely, if an industrial hygienist testified that the plaintiff’s workplace
    25 Further, as noted above, Plaintiffs did not object to the testimony of Defendant’s industrial
    hygienists.
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    contained no asbestos, the Commission could properly determine that the plaintiff
    had failed to prove a causal connection.                   In Vaughn, the “plaintiff argued the
    Commission improperly required him to produce scientific or medical evidence of
    exposure to asbestos for the relevant time period while in defendant’s employ.” 
    Id. at 4
    73, 598 S.E.2d at 631 (citation omitted). This Court held that “[p]laintiff [wa]s
    correct that there [wa]s no need for such expert testimony.” 
    Id. “This does
    not mean,
    however, that the Commission cannot consider expert testimony, or the lack thereof,
    along with lay testimony, in weighing the evidence and determining whether
    claimant has met his burden of proof.” 
    Id. at 4
    73, 598 S.E.2d at 632. The Commission
    was free to consider all the evidence, lay and expert, to inform its conclusion that
    Plaintiffs failed to meet their burden on the issues of exposure and causation.
    In addition, Plaintiffs acknowledge that their contention is not accurate,
    admitting: “The Commission did rely on [Defendant’s expert] Dr. Ghio who is a
    medical expert.” Plaintiffs then incorrectly argue: “The only other medical expert
    offered by [] Defendant was Dr. [Selwyn] Spangenthal” (“Dr. Spangenthal”).26 For
    example, Defendant also presented live testimony from Dr. Kenneth Samuel Karb,
    26  Further, Plaintiffs are also incorrect in claiming Dr. Spangenthal “testified that [Plaintiffs]
    had sufficient exposure to asbestos to cause a disease.” Dr. Spangenthal was asked by Plaintiffs’
    counsel, for each Bellwether Plaintiff: “And if [the individual Plaintiff’s] testimony is true [concerning
    his exposure to asbestos in the factory], assuming that for the sake of my question, . . . would that
    exposure have been significant . . . enough to cause disease?” Dr. Spangenthal responded “yes,” but
    added “I just assume that, you know, [Plaintiff] knows where he works, and that’s his impression of
    what . . . his exposure was, and that’s what I’ve noted down. Whether it’s true or not, I have no idea.”
    The Commission was not required to give weight to Bellwether Plaintiffs’ own accounts of alleged
    asbestos exposure—whether given as testimony during the hearings, or given to physicians taking
    their histories.
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    Dr. David Allen Hayes (“Dr. Hayes”), and Dr. Roggli. Deposition testimony was
    presented from, inter alia, Dr. Oury, Dr. Gregory S. Parsons, Dr. Robert Reuter, and
    Dr. Sporn. Medical records and reports were entered into evidence from multiple
    additional physicians.
    Dr. Roggli offered, inter alia, his opinions that he would not “typically expect
    to see asbestos-related disease” associated with work within the tire industry, and
    the medical literature supports his opinion that tire plant workers are not exposed to
    a greater risk of asbestosis than the general public; that in his medical practice he
    has “not seen any asbestos-related lung cancers or asbestosis, to my recollection, from
    anybody . . . working with the tire industry”; that, contrary to Plaintiffs’ evidence, the
    appearance of “a few short chrysotile fibers in the lung” of an individual is “exactly
    what you find in lung tissue from the people from the general population”; that it
    would be very unusual to examine lung tissue from the general population and fail to
    find any measurable asbestos fibers; that, contrary to Plaintiffs’ evidence, asbestos
    fibers less than five microns in length “would not be disease-producing”; that
    approximately ninety percent of the scientific community was of the same opinion;
    and that, based upon his pathological analysis of Plaintiff Jones’ lung sample, he was
    “completely ruling out asbestosis[.]” Further, based on his fiber count analysis of
    Plaintiff Jones’ lung tissue, Dr. Roggli testified to his opinion “within a reasonable
    degree of scientific certainty,” that neither Plaintiff Jones, nor “a person in [Plaintiff]
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    Jones’ position” would have received “sufficient exposure to asbestos at [the factory]
    . . . to contribute to an asbestos-related disease[.]”
    Dr. Ghio testified concerning why he did not trust the Plaintiffs’ experts
    methodology when only ten percent of Plaintiffs diagnosed as having asbestosis also
    showed signs of pleural plaques:
    [DR. GHIO:] . . . . Eighty percent of the time [patients] have
    pleural plaques if they have significant exposure to asbestos.
    ....
    THE COURT: Well, let me ask it more specifically. On a
    . . . one zero,[27] are they going to have pleural plaques?
    [DR. GHIO]: Yes, eighty percent of them will.
    THE COURT: Okay.
    [DR. GHIO]: If it’s truly the result of significant exposure to
    fibers, eighty percent of the chest x-rays[—S]omewhere
    between fifty and eighty percent—and I like the eighty
    actually. More of the studies have come out with eighty
    percent will show pleural plaques if it is attributable—if it’s
    truly the result of fiber exposure. [Emphasis added].
    Dr. William Franklin Alleyene, II (“Dr. Alleyene”), Plaintiffs’ expert, agreed that
    pleural plaques will be present in approximately eighty percent of people who have
    asbestosis. Dr. Ghio further testified:
    [DR. GHIO:] [T]here have been many diagnoses of
    asbestosis that I’ve made on individuals who have come in,
    and they’re part of that twenty percent or the fifty percent
    that don’t have pleural plaques. But that’s an individual.
    27   The deputy commissioner is referring to a B-readers assessment of 1/0 as explained in
    finding of fact 25.
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    When you have a group of 157, you have the benefit of
    numbers here. And if in 157 individuals you’re looking at
    zero plaques, then you have to come to some conclusion
    about the exposure.
    THE COURT: Well, you’re saying—basically from your
    testimony, if I’m—and I want to make sure I understand
    what you’ve testified correctly. I’m just trying to clarify.
    Out of the 158, you would expect something like 120 to
    have pleural plaques on their x-rays.
    THE WITNESS: That is correct.
    THE COURT: Therefore, and because there are no pleural
    plaques, if other people are diagnosing one zeros on 157 x-
    rays, [and] somewhere about . . . 75 or so to 120 don’t have
    pleural plaques, you’re saying that those x-rays generally
    are being misread.
    [DR. GHIO]: That’s correct.
    ....
    [DR. GHIO]: And there’s nothing in the medical literature
    to support this possibility.
    Dr. Ghio then expresses his medical expert opinion that Plaintiffs were not exposed
    to sufficient asbestos working at the factory to cause disease:
    I don’t think that any contribution . . . from the work
    environment [in the factory] would significantly increase
    one’s risk [of contracting an asbestos-related disease].
    But[, hypothetically,] these individuals may have [been
    exposed to significant amounts of asbestos fibers in prior
    employment]. . . . I believe that they could be diagnosed to
    have asbestosis if they’re a Continental Tire worker, but it
    had nothing to do with the environment at [the factory].
    THE COURT: To any degree?
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    [DR. GHIO]: To any degree.
    In addition, Plaintiffs’ expert Dr. Alleyene, testified concerning the superiority
    of CT scans over x-rays in diagnosing asbestosis:
    X-rays are based on technology that’s over a hundred years
    old, and it’s like looking at something with a naked eye
    when you’ve got a microscope right next to you. And I can
    see things on a CT scan that is—are much more detailed
    [and] three-dimensional, and, also, it takes a lot of the
    guess work out of it. The—somebody looks at an x-ray, a
    B-reader, and they say, “Well, gee, I see these shadows, and
    they look like 1/0” versus on a CT scan I can see fibrosis, I
    can see pleural plaquing, I can see all types of things and
    so when physicians talk about making that diagnosis
    whether it’s in a board review course or anything, no one
    even mentions a B-read chest x-ray. That is something
    that exists only in the courtroom. Physicians, when we talk
    about asbestosis, when we talk[] about diagnosing
    asbestosis and how to manage patients with asbestosis, we
    speak specifically about high resolution CT scans. We don’t
    even talk about an x-ray other [than] to say, “Gee, if your
    x-ray is unclear or suspicious, you get a CT scan to
    confirm.”
    The deputy commissioner, based on Dr. Alleyene’s testimony, proposed that Plaintiffs
    and Defendant agree to allow independent doctors who were experts in asbestos-
    related diseases to administer and analyze high resolution CT scans of every living
    Plaintiff. Defendant wanted the deputy commissioner to order Plaintiffs to obtain
    high resolution CT scans, and Defendant agreed to pay for the procedures and the
    analysis. Plaintiffs’ counsel informed the trial court that they would not agree to
    having Plaintiffs undergo high resolution CT scans.        The deputy commissioner
    responded that Plaintiffs’ refusal “cuts both ways. And based on—based on the
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    evidence I have heard thus far, I again say that decision . . . cuts both ways—okay—
    cuts both ways because [P]laintiffs have the burden of proof here[.]”
    Both Plaintiffs and Defendant presented medical expert testimony that the
    only certain method of diagnosing asbestosis is to examine a sufficient sample of the
    patient’s lung tissue. Plaintiffs’ attorney, in response to the deposition testimony of
    Dr. Spangenthal that CT scans were “the gold standard” for diagnosing asbestosis,
    stated: “Actually, the gold standard would probably be a biopsy, isn’t it?”        Dr.
    Spangenthal agreed, noting that he was referring to procedures that he would
    generally perform on living patients. When Plaintiffs’ expert, Dr. Alleyene, was
    asked if there were any symptoms that are “pathopneumonic” for asbestosis—i.e. “a
    sign or a symptom or a finding that would be so closely correlated with a specific
    disease entity as to be virtually diagnostic”—he responded:
    There are what we call asbestos bodies[.] And if one found
    a certain concentration of asbestos bodies per gram of lung
    tissue, that would be pathopneumonic of asbestosis.
    Having said that, the way that you would get that tissue
    would require a procedure that is fairly invasive called an
    open-lung biopsy where they literally spread your ribs,
    take a piece of lung tissue that would be significantly larger
    than one could obtain from other methods[.] This—you
    would get a nice wedge of lung tissue, literally. And if they
    then prepped that tissue . . . and looked at it under an
    electron microscope, you could see these linear—they’re not
    fibers but they’re actually coated asbestos fibers, and they
    call them asbestos bodies[.] And if one has an open-lung
    biopsy and if one has the finding of these asbestos bodies
    or sufficient numbers of these asbestos bodies either in the
    tissue itself or in the lung fluid . . ., then that would be
    pathopneumonic.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    Q. Short of taking a wedge of somebody’s lung, there’s
    nothing pathopneumonic about asbestosis?
    A. That is correct.
    Dr. Oury agreed with Dr. Alleyene that “pathology [is] still the only way to
    definitively diagnose asbestosis[.]” Dr. Hayes also testified for Defendant, and agreed
    that pathology is the most accurate way to diagnose asbestosis, followed by high
    resolution CT scan. When Dr. Roggli was asked: “Would it be safe to say that, if you
    don’t have it pathologically, you don’t have it?” He responded: “Correct. That is
    assuming that you have a reasonable, decent sample of tissue, that would be correct.”
    Dr. Roggli also testified that the best tool for diagnosing asbestosis is “pathologic
    examination,” followed by “high-resolution CT—regular CT would be less sensitive,
    and least sensitive would be the routine chest x-ray.” Plaintiffs provided Defendant
    lung tissue from five of the eighteen deceased Plaintiffs; Defendant submitted lung
    tissue from all five for pathological examination, and none of the lung tissue from
    these deceased Plaintiffs, including Plaintiff Hinson, showed asbestos bodies or other
    signs of disease related to asbestos exposure.
    In Plaintiffs’ brief, they argue that the “Commission ignored the testing done
    by Plaintiffs’ pathologists. This testing irrefutably showed excess levels of asbestos
    in the lungs of the workers.” However, Plaintiffs did not offer testimony from any
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    pathologists.28 The Commission can “consider expert testimony, or the lack thereof,
    along with lay testimony, in weighing the evidence and determining whether
    claimant has met his burden of proof.” Vaughn, 165 N.C. App. at 
    473, 598 S.E.2d at 632
    .
    The common issues findings of fact demonstrate that evidence from medical
    experts factored heavily in the determinations of the Commission—see findings 1, 25,
    26, 27, 28, 29, 30, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, and 44—the Commission
    simply gave the testimony of certain of Defendant’s medical experts greater weight.
    It was the province of the Commission to determine the credibility of, and the weight
    to be given to, the various expert witnesses, including the medical experts. 
    Wise, 231 N.C. App. at 164
    , 752 S.E.2d at 175–76.
    Because Plaintiffs had “the burden of proving [their claims] by . . . a
    ‘preponderance of the evidence[,]’” they were required to “present credible evidence of
    [sufficient asbestos] exposure[.]” 
    Id. We hold
    that the Commission properly relied on
    both medical and non-medical evidence—expert and lay—when considering the issue
    of causation in this matter. Plaintiffs’ refusal to agree to certain more accurate
    medical procedures was also proper to consider. 
    Id. Plaintiffs’ argument
    is without
    merit.
    3. Extrapolating the Evidence
    28
    The only record evidence of Plaintiffs having obtained analysis of a deceased Plaintiff’s lung
    tissue was the fiber count done on Plaintiff Jones’ lung tissue by Rigler—who is not a medical doctor.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    As part of the section challenging certain findings of fact, Plaintiffs include the
    following two sentence argument: “[T]he Commission is attempting to use lung tissue
    samples from some workers to determine the amount of asbestos in the lungs of all
    [Plaintiffs]. That is speculation and there was no evidence of the relevance of the
    lung pathology to other workers.” We hold the results of the lung tissue analyses of
    the deceased Plaintiffs were a proper factor for the Commission to consider, and were
    relevant to the Commission’s decision.      Plaintiffs’ brief includes testimony from
    multiple witnesses contending that exposure to asbestos in the curing department
    was worse than anywhere else in the plant. Plaintiffs argue on appeal that “[t]he
    condition of the insulation was especially bad in the curing department.” In finding
    32, the Commission determined: “Pathological examination of lung tissue is a
    definitive method of determining whether an individual has an asbestos-related
    disease.” In finding 37, the Commission found that Plaintiff Hinson worked in the
    factory
    for 32 years, mainly in the curing department. The curing
    department had the highest concentration of insulated
    piping in the factory, with much of it at floor level or in
    exposed trenches. According to decedent Hinson, he was
    also exposed to significant asbestos dust from using a band
    saw to cut large asbestos gaskets. If [P]laintiffs’ arguments
    are correct, decedent Hinson would have been exposed to a
    significant amount of airborne asbestos. . . . . Dr. Craig
    Hart at York pathology performed [P]laintiff Hinson’s lung
    autopsy. Dr. Hart found no evidence of asbestos bodies or
    fibrosis, but did see evidence of smoking. The tissue was
    sent to Dr. Oury, who examined the sample and confirmed
    Dr. Hart’s conclusions. Although it was not required for
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    diagnostic purposes due to the lack of fibrosis, a fiber count
    analysis was done by Dr. Oury upon [D]efendant’s request.
    The fiber count analysis found 5 asbestos bodies per gram,
    which is a level well below that seen in individuals with
    asbestosis and in the range of control individuals with no
    history of asbestos exposure.
    Despite Plaintiffs’ arguments and evidence suggesting Plaintiff Hinson should
    have been exposed to more airborne asbestos than Plaintiffs who worked in other
    areas of the factory, Plaintiff Hinson’s lung pathology demonstrated that not only did
    he not have asbestosis, his exposure to asbestos was at “a level well below that seen
    in individuals with asbestosis and in the range of control individuals with no history
    of asbestos exposure.”    This evidence was relevant to the Commission’s decision
    regarding the overall levels of airborne asbestos in the factory, and properly
    considered for that purpose.
    Plaintiffs also argue that they were exposed to significant levels of asbestos in
    other areas of the factory. Plaintiffs claim that the asbestos insulation in the plant
    that “was in a damaged, deteriorated and [] dangerous condition” was “located in the
    work areas of the employees including the [P]laintiffs herein.” One of Plaintiffs’
    witnesses testified that “the insulation was torn off, beaten off, and looked ragged[,]”
    and “that this condition was consistent throughout the plant.” Plaintiffs agree in
    their brief that “[t]he poor condition of the asbestos insulation was not restricted to a
    single area but was consistent throughout the plant.” In addition, Plaintiffs argue
    they were exposed to airborne asbestos fibers throughout the plant due to the use of
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    talc contaminated with chrysotile asbestos; and the removal, replacement, and repair
    of gaskets and brakes that contained chrysotile asbestos. Plaintiffs argued to the
    Commission that the factory was “a very dusty plant” and that any plaintiff who
    worked throughout the factory “would have been in each of these departments and
    subject to the same type of exposures [as] everyone else.”
    In finding 34, the Commission stated: “Of the five deceased [P]laintiffs who
    had post-mortem pathological study of their lung tissue, (Walter Hinson, Johnnie
    Jones, Charles Gibson, Homer Hunt, and Lloyd Cox), none had pathological evidence
    of asbestosis. Pathology is the most reliable method to diagnose asbestosis.” In
    findings 38, 39, 40, and 41, the Commission determined that deceased Plaintiff Jones
    worked for twenty-five years in the calendar area—where he would have been
    exposed to talc, along with pipe insulation; deceased Plaintiff Gibson worked for
    thirty-one years in the tire-building and warehouse departments; deceased Plaintiff
    Hunt worked for seventeen years throughout the factory as a mechanic—which would
    have exposed him to the alleged brake-related asbestos dangers as well as all other
    alleged causes of airborne asbestos in the factory; and deceased Plaintiff Cox worked
    for thirty-one years in the stock and bead preparation areas.       The Commission
    determined in finding 42: “Despite Plaintiffs’ theories of exposure, pathology results
    from the lung tissue of five long-term employees from a variety of departments and
    factory locations uniformly show a lack of fibrosis, a lack of asbestos bodies, and a
    lack of fibers.”
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    The above findings of fact illustrate the relevance of the pathological
    examinations to the general issue of whether employment at the plant served to
    expose Plaintiffs to asbestos of the type and quantity that could cause or significantly
    contribute to the development of an asbestos-related disease.         The lung tissue
    pathology was direct evidence that none of the deceased Plaintiffs had asbestosis or
    other asbestos-related diseases, and was also circumstantial evidence supporting the
    Commission’s determination that Plaintiffs had failed to prove “a causal connection
    between asbestosis and employment at the . . . factory.”
    4. The Entire Record
    Plaintiffs challenge the Commission’s findings 16, 19, 21, 23, 43, 44, and 45,
    because the Commission stated that it was basing its determinations on “the greater
    weight of the evidence in view of the entire record.” Plaintiffs argue that the “entire
    record” language demonstrates that the Commission based these findings, in part, on
    incompetent evidence and, therefore, these findings and conclusions are invalid.
    Plaintiffs argue: “The ‘entire record’ consisted of the air sampling and testimony of
    experts regarding the amount of exposure for each [P]laintiff and the amount
    necessary to cause disease. As stated herein, [Plaintiffs] find[] that such evidence is
    not competent. Regardless, the Commission based its opinions on that evidence.”
    Plaintiffs also contend that “all of the testimony relied upon by the Commission to
    establish the levels of exposure were based upon air sampling.” As the Commission’s
    findings of fact, and the small sampling of the expert testimony included herein
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    demonstrates, the Commission relied primarily on expert medical testimony, not air
    sampling, and Plaintiffs’ argument fails for this reason.
    In addition, “[b]efore the Commission makes findings of fact, it ‘must consider
    and evaluate all of the evidence. Although the Commission may choose not to believe
    the evidence after considering it, it may not wholly disregard or ignore competent
    evidence.’” File v. Norandal USA, Inc., 
    232 N.C. App. 397
    , 400, 
    754 S.E.2d 202
    , 205
    (2014) (citation omitted). It would have been improper for the Commission not to
    have considered “the entire record” before making its determinations. Further, the
    Commission is not required to make specific findings indicating the evidence it is not
    relying on. Bryant v. Weyerhaeuser Co., 
    130 N.C. App. 135
    , 139, 
    502 S.E.2d 58
    , 62
    (1998).     Finally, “findings of fact which are supported by competent evidence are
    conclusive on appeal, even though other incompetent evidence may have been
    improperly admitted.” 
    Kennedy, 101 N.C. App. at 33
    , 398 S.E.2d at 682 (citation
    omitted). This argument is without merit.
    C. Findings of Fact
    Plaintiffs contest certain findings of fact, in whole or in part.29 Our review is
    limited to “whether the findings of fact are supported by competent evidence[.]”
    Penegar, __ N.C. App. at __, 815 S.E.2d at 394 (citation omitted). Uncontested
    findings are binding on appeal. 
    Id. We include
    as “unchallenged” many findings of
    29Plaintiffs challenge some of the “common issue” findings in certain individual briefs, but not
    others. For the sake of clarity, we address the challenges from all of the bellwether briefs related to
    common issues in this opinion.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    fact that Plaintiffs purport to challenge on appeal—because Plaintiffs’ “challenges” to
    these findings are not based on any alleged insufficiency of supporting evidence. 
    Id. Plaintiffs challenge
    certain findings based on the following sentence: “In
    Findings of Fact 43, 44, 45, 47 the Commission relies on evidence that is not
    competent for the reasons set forth herein.” That is the totality of the challenge, and
    it is not sufficient for appellate review. Plaintiffs challenge findings 12, 13, 14, 15,
    16, 18, 19, 21, and 23 by arguing that the Commission should not have relied on the
    air sampling reported in these findings. However, Plaintiffs do not contend that the
    findings themselves are not supported by competent evidence. These findings simply
    state uncontested facts concerning the air sampling done at the factory, and do not
    include any indication of how, or if, the Commission relied on these findings to make
    its decisions.30
    Plaintiffs challenge findings 15, 35, 36, 37, 38, 39, 40, 41, 42, 44, and 47, on the
    basis that the Commission “gave more credibility to [the opinions and testimony of]
    Defendant’s experts” and “failed to consider, and plainly ignored, the evidence that
    contradicted” the opinions of Defendant’s experts. Again, this is not an argument
    concerning whether there was sufficient evidence to support these findings—
    Plaintiffs simply argue that they disagree with the weight and credibility
    30  Findings 16, 19, 21, and 23 are ultimate findings, but they are not properly challenged in
    this section.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    determinations of the Commission.31 That is not a valid challenge to findings of fact,
    and this Court is without authority to make the determinations Plaintiffs ask of it:
    In passing upon issues of fact, the Industrial Commission
    is the sole judge of the credibility of the witnesses and the
    weight to be given to their testimony. The Commission
    may accept or reject the testimony of a witness solely on
    the basis of whether it believes the witness or not. The
    findings of the Industrial Commission are conclusive on
    appeal when supported by competent evidence even though
    there be evidence to support a contrary finding.
    Hilliard v. Apex Cabinet Co., 
    305 N.C. 593
    , 595, 
    290 S.E.2d 682
    , 683–84 (1982)
    (citations omitted). Therefore, these “unchallenged” findings of fact are binding on
    appeal.32 Penegar, __ N.C. App. at __, 815 S.E.2d at 394.
    Plaintiffs challenge finding 11, arguing that the Commission’s determination
    that the greater weight of the evidence did not support a finding that there were high
    levels of airborne particulates in the curing department “ignores evidence and
    misstates the evidence. Plaintiff[s] never suggested that workers were damaging the
    asbestos on the pipes every minute of every day. It was occasional exposures.” We
    agree that “high levels of airborne particulates in the curing department originating
    from damaged pipe insulation and gasket-sawing” would have been intermittent.
    However, there was sufficient evidence to support this finding as written. As the
    Commission stated in its ultimate finding 43:
    In occupational disease cases, a causal connection between
    31 Finding 47 is an ultimate finding or conclusion, but Plaintiffs’ argument is insufficient to
    challenge this conclusion as well.
    32 We further hold that all these findings of fact are supported by competent record evidence.
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    the employment and the alleged disease must be proven.
    This analysis includes the extent of exposure. Of necessity,
    evidence on the subject of causation in these cases is often
    circumstantial. Given the evidence of air contaminant
    measurements taken at [D]efendant’s factory, the
    pathology evidence collected from workers’ lungs, and the
    scientific and epidemiological literature presented on the
    subject, the greater weight of the evidence in view of the
    entire record does not demonstrate a causal connection
    between asbestosis and employment at the . . . factory.
    The Commission is correct in its statement of law: “In the case of occupational
    diseases proof of a causal connection between the disease and the employee’s
    occupation must of necessity be based on circumstantial evidence.” 
    Booker, 297 N.C. at 476
    , 256 S.E.2d at 200. The pathology evidence, the testimony of Defendant’s
    medical experts and industrial hygienists, the scientific and epidemiological
    literature, and other evidence presented, constituted sufficient evidence to support
    the finding that “the greater weight of the evidence [did] not support” that there were
    “high levels of airborne particulates in the curing department originating from
    damaged pipe insulation and gasket-sawing”—even though Plaintiffs presented
    evidence in support of a contrary finding.
    Plaintiffs also argue that in finding 12 the Commission “completely ignored the
    fact that the 1979 study was not measuring for asbestos.” However, finding 12
    correctly states that the study “measured for dust—both airborne and respirable, as
    well as petroleum distillates, rubber solvent, Benzene, and Toulene.         The dust
    measurements would have measured any particulates in the air—whether the
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    particulates were asbestos, talc, or something else.” We hold that all of the “common
    issues” findings of fact included in this opinion are binding on appeal.
    D. Ultimate Findings and Conclusions of Law
    Plaintiffs do not challenge the following ultimate findings/conclusions and they
    are therefore binding on appeal:
    46. Plaintiff Charles Wilson[], one of the “initial five”
    plaintiffs, alleges that he also contracted colon cancer as a
    result of exposure to asbestos at the . . . factory. However,
    the greater weight of the evidence in view of the entire
    record shows that colon cancer is an ordinary disease of life
    to which the public is equally exposed. The greater weight
    of the evidence in view of the entire record does not show
    that colon cancer is characteristic of persons engaged in the
    tire manufacturing industry or that working at the
    . . . factory placed those who worked there at an increased
    risk of developing colon cancer.
    47. Plaintiff Epps[], one of the “initial five” plaintiffs,
    alleges that he also contracted tonsil cancer as a result of
    exposure to asbestos at the . . . factory. However, the
    greater weight of the evidence in view of the entire record
    shows that tonsil cancer is an ordinary disease of life to
    which the public is equally exposed. The greater weight of
    the evidence in view of the entire record does not show that
    tonsil cancer is characteristic of persons engaged in the tire
    manufacturing industry or that working at the . . . factory
    placed those who worked there at an increased risk of
    developing tonsil cancer.
    Plaintiffs challenge ultimate finding 16, which states:
    16. The greater weight of the evidence in view of the entire
    record shows that plaintiffs were neither exposed to
    airborne asbestos as a result of damaged pipe insulation in
    such form and quantity and with such frequency as to
    cause or significantly contribute to the development of
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    HINSON V. CONT’L TIRE THE AMS.
    Opinion of the Court
    asbestosis, nor were plaintiffs exposed to the hazards of
    asbestosis through this method in this employment for 30
    days or parts thereof within a seven month consecutive
    period which proximately augmented the disease process
    of asbestosis to the slightest degree.
    Plaintiffs argue: “In short, the Commission found that [P]laintiffs were not exposed
    to asbestos in a sufficient amount from damaged pipe insulation to cause asbestosis.
    This finding was based upon ‘the entire record.’” Plaintiffs then state:
    The Commission also found the exposures from asbestos-
    containing talc, gaskets and brakes were insufficient to
    cause disease based upon the entire record. (Findings of
    Fact 19, 21, 23). The “entire record” consisted of the air
    sampling and testimony of experts regarding the amount
    of exposure for each [P]laintiff and the amount necessary
    to cause disease. As stated herein, Plaintiff[s] find[] that
    such evidence is not competent.           Regardless, the
    Commission based its opinions on that evidence.
    Plaintiffs contest ultimate findings 43 and 45 on the same grounds.33 We have
    already addressed Plaintiffs’ argument above—in section IV. B. 4. of this opinion—as
    well as noting that Plaintiffs failed to challenge the Commission’s “last injurious
    exposure” determinations made pursuant to N.C.G.S. § 97-57. In addition, we hold
    that there is sufficient competent record evidence to support the Commission’s
    ultimate findings.34 
    Culpepper, 93 N.C. App. at 247
    , 377 S.E.2d at 780.
    33 All of these ultimate findings are determinations that Plaintiffs’ alleged injuries did not
    “arise out of” their employment at the factory. See 
    Culpepper, 93 N.C. App. at 247
    , 377 S.E.2d at 780.
    34 To the extent, if any, that the ultimate findings are, or contain, conclusions of law, Plaintiffs
    abandoned any challenge to them because they have failed to argue that they are not supported by the
    findings of fact. In addition, we hold that any conclusions in the common issues section of the
    bellwether opinions and awards are supported by the findings of fact.
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    Opinion of the Court
    Findings 43 and 45 state in relevant part:
    43. . . . .   Given the evidence of air contaminant
    measurements taken at [the] factory, the pathology
    evidence collected from [deceased Plaintiffs’] lungs, and the
    scientific and epidemiological literature presented on the
    subject, the greater weight of the evidence in view of the
    entire record does not demonstrate a causal connection
    between asbestosis and employment at the . . . factory.
    ....
    45. The greater weight of the evidence in view of the entire
    record does not show that [P]laintiffs, through their
    employment at [the] factory, were exposed to asbestos in
    such form and quantity and used with such frequency as to
    cause or significantly contribute to the development of
    asbestosis[.]
    Because both ultimate findings 43 and 45 include determinations that
    Plaintiffs failed to meet their burden of proving a sufficient causal relationship
    between employment at the factory and their alleged asbestosis, these ultimate
    findings defeat Consolidated Plaintiffs’ asbestosis claims. Because the Commission
    determined in “findings” 46 and 47 that Plaintiffs have failed to prove that either
    colon cancer or tonsil cancer are “occupational diseases” as defined by N.C.G.S. § 97-
    53(13), these determinations also apply to the outstanding consolidated cases.
    E. Conclusion—Common Issues Arguments
    We affirm the Commission’s common issues determinations. It did not err in:
    (1) Determining Plaintiffs failed to prove a causal connection between employment at
    the factory and asbestosis; (2) its determination, based upon the facts presented, that
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    Opinion of the Court
    Plaintiffs failed to prove that either colon cancer or tonsil cancer were occupational
    diseases pursuant to N.C.G.S. § 97-53(13); or (3) its unchallenged determination that
    Plaintiffs were not last injuriously exposed to the hazards of asbestosis at the factory.
    Further, we hold that the Commission’s findings and ultimate findings are supported
    by competent evidence, and its conclusions and rulings are supported by the findings.
    V. Plaintiff Hinson’s Appeal
    Although we affirm the Commission’s opinion and award based on our holdings
    set forth above, we will also address the findings and conclusions specific to Plaintiff
    Hinson. Initially, Plaintiff Hinson does not make any argument that the findings of
    fact fail to support the conclusions of law; therefore, the conclusions of law stand.
    Penegar, __ N.C. App. at __, 815 S.E.2d at 394. For example, Plaintiff argues that, in
    support of conclusion of law 3, “the Commission . . . relied, in large part, on a
    determination of the amount of asbestos that [P]laintiff inhaled and how much was
    necessary to cause disease.” Conclusion 3 states in part: “[I]n this case, it was not
    established, by the preponderance of the evidence in view of the entire record, that
    [Plaintiff] contracted asbestosis or any asbestos-related condition.” Plaintiff argues
    this conclusion is not supported by competent evidence, but does not make an
    argument that the findings of fact fail to support this conclusion—therefore, this
    conclusion of law stands. 
    Id. Assuming, arguendo,
    Plaintiff Hinson has preserved challenge to the findings
    and conclusions specific to him, we hold that competent evidence supports the
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    Opinion of the Court
    relevant findings of fact and ultimate findings, which support the Commission’s
    relevant conclusions of law. 
    Id. Plaintiff Hinson
    does not challenge finding 34 which
    states in part that the “post-mortem pathological study of” Plaintiff Hinson’s “lung
    tissue” revealed no “pathological evidence of asbestosis.      Pathology is the most
    reliable method to diagnose asbestosis.” Findings 55, 57, 58, 60, 61, 62, and 63 are
    also unchallenged. These findings include determinations by multiple doctors that
    Plaintiff Hinson’s x-rays did not show evidence of pleural abnormalities or asbestosis;
    that after Plaintiff Hinson told his treating physician of his asbestosis diagnosis, his
    physician told Plaintiff Hinson “to inform his attorney that the abnormal x-ray was
    due to pneumonia”; and that though Plaintiff Hinson “testified vehemently that he
    never smoked,” medical records and his pathology results indicated he had “a remote
    smoking history.”
    The Commission found in findings 37 and 64 that during pathological
    examination of Plaintiff Hinson’s lung tissue, “Dr. Hart found no evidence of asbestos
    bodies or fibrosis, but did see evidence of smoking[,]” a conclusion “confirmed” by Dr.
    Oury, who also conducted a fiber count analysis and found results “well below that
    seen in individuals with asbestosis and in the range of control individuals with no
    history of asbestos exposure.” Plaintiff Hinson’s only argument concerning these
    findings is that the Commission “ignore[d] the pathology findings of [P]laintiff’s
    experts.” As noted above, Plaintiffs did not present any evidence from pathologists.
    To the extent Plaintiffs—including Plaintiff Hinson—mean to include non-
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    Opinion of the Court
    pathologist medical doctors, or non-physician scientists who work with lung tissue,
    under the definition of “pathologists,” it was the province of the Commission to weigh
    the evidence and the credibility of the witnesses. Because there is some competent
    evidence to support these findings, they are conclusive on appeal. Plaintiff challenges
    finding 65, in which the Commission states that Defendant’s medical experts were
    “given greater weight than” Plaintiffs’. Plaintiff Hinson’s challenge to this finding is
    based on Plaintiffs’ rejected “entire record,” “air sampling,” and “fiber year theory”
    arguments.
    Our review of the record demonstrates that the evidence supports the ultimate
    finding—included in finding of fact 66 and conclusions of law 2 and 4—that Plaintiff
    Hinson failed to prove a causal connection between his employment at the factory
    and his alleged asbestosis. We further hold that the Commission’s findings, which
    are based on substantial competent evidence, support conclusion 3, in which the
    Commission determined that Plaintiff Hinson failed to prove he had asbestosis.
    Finally, Plaintiff Hinson does not challenge the determination made pursuant to
    N.C.G.S. § 97-57 that he was not “last injuriously exposed” to the hazards of
    asbestosis at the factory. For all the above reasons, we affirm the denial of Plaintiff
    Hinson’s claim.
    AFFIRMED.
    Judges DIETZ and COLLINS concur.
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