CDC Study Finds Mesothelioma Death Rates Higher Than Projections
On March 3, 2017, the Centers for Disease Control and Prevention (CDC) published a study assessing malignant mesothelioma mortality rates in the United States between the years 1999-2015. The Study – apparently the first of its kind to assess mesothelioma mortality rates based on International Classification of Disease, 10th Revision (ICD-10) coding found on death certificates – appears to contradict the consensus opinion by physicians and analysts which projected a gradual decline in the number of mesothelioma deaths in the United States as a result of the reduced use of asbestos since the 1970's. Instead, the authors not only found that the number of deaths increased over the study period by almost 5% (from 2,479 in 1999 to 2,597 in 2015), the data shows there were more deaths due to malignant mesothelioma per annum in the last eight years of the study (2,746.5) than in the first nine (2,583.2).
Most significantly, while the bulk of the afflicted were old enough to have entered the workforce while asbestos was still in common use, an apparently surprising number of deaths were identified in populations that came of age after the risks of asbestos were identified and its use regulated, including 138 deaths among persons aged 25-34 and 544 total deaths among persons aged 35-44. Based on these findings, the authors conclude:
The continuing occurrence of mesothelioma deaths, particularly among younger populations, underscores the need for maintaining efforts to prevent exposure and for ongoing surveillance to monitor temporal trends.
We anticipate plaintiffs and other interested persons will cite the Study as support for the need to increase regulation. Indeed, in an opinion piece published on HuffingtonPost.com, a member of the "asbestos victim community" cites the Study as supporting the authors' belief that: "we as a country must do much more to regulate asbestos and mitigate the risk of exposure…". We further anticipate that plaintiffs' counsel and their experts may cite the Study as support for the conclusion that the risk associated with low level exposure to all types of asbestos fiber has been historically understated. We believe such conclusions are simply not supported by the data.
First, while the data shows an increase in the total number of deaths over the Study period, this does not equate to increased risk. In fact, the Study found that the overall risk of developing mesothelioma declined 21.7% during the same time frame, from 13.96 cases per million in 1999 to 10.93 cases per million in 2015. This seemingly contradictory result may be explained by the Study’s methodology, which calculated age-adjusted death rates by dividing the total number of cases in a given year by 2000 U.S. Census standard population age distribution data for all persons who reached the age of 25 and older in a given year. But this does not appear to be the whole explanation.
The primary factor that drove the higher than expected number of cases was not deaths among those under the age of 44, it was the unanticipated rise in the deaths among those over the age of 85, which the authors describe as a “significant increase." Taken together with persons aged 75-84, these two groups are 6% of the total U.S. population yet account for 51.7% of all deaths identified in the Study (23,381 of 45,221). By contrast, the Study found that the number of cases "decreased significantly" for persons in the 45-54, 55-64, and 65-74 population subsets. And while it is unclear whether the death rate for persons aged 25-44 increased or decreased over the course of the Study, the total number of cases among this population (684 over 15 years) is insufficient to account for the overall rise in the mortality described by the Study. We believe the authors characterize these deaths as "substantial" because they were not projected at this point.
In short, while true that total cumulative deaths increased during the Study period, the data shows this was primarily due to a greater than expected number of deaths among those over the age of 75, not an across the board increase or stagnant death rate for all populations. Also, the increasing life expectancy may have played a role, although not addressed in the study.
Second, the Study’s reliance on the ICD-10 codes to determine the cause of death does not necessarily mean a given decedent was exposed to any significant source of asbestos. While generally accepted that exposure to asbestos may increase the risk of developing mesothelioma, it is also generally accepted that mesotheliomas can develop in persons with no known source of commercial, industrial, or household exposure to asbestos.
Finally, we note that any attempt to compare death rates based on the ICD-10 data with prior studies to find that the overall rates were “higher than projected” is problematic. Earlier studies used entirely distinct methodologies, were based upon multiple assumptions (such as exposure levels and projected latency periods), and failed to consider alternate causes or sources of mesothelioma, such as naturally occurring asbestos (i.e., erionite) and similarly toxic minerals, therapeutic radiation, as well as previously non-existent causes such as carbon nanotubes.
 Mazurek JM, Syamlal G, Wood JM, Hendricks SA, Weston A. Malignant Mesothelioma Mortality — United States, 1999–2015. MMWR Morb Mortal Wkly Rep 2017;66:214–218. DOI: http://dx.doi.org/10.15585/mmwr.mm6608a3 (hereafter cited as the "CDC Report").
 Prior to the adoption of the 10th revision of the ICD codes, malignant mesothelioma did not have a discrete code.
 Se eAsbestos exposure is still making people sick, CNN.com, located at http://www.cnn.com. /2017/03/03/health/asbestos-mesothelioma-death-rates-study/
 E.g., Lilienfeld DE, et al., Projection of asbestos related diseases in the United States, 1985 – 2009, I. Cancer. Br J Ind Med 1988;45:283-91.