By Sonya Lunder

Fifty years after a landmark medical study definitively established that asbestos kills, the exact death toll remains unknown (Selikoff 1964).

EWG Action Fund’s exclusive analysis finds that exposure to asbestos kills at least 12,000 to 15,000 Americans a year. Despite a significant reduction in the use of asbestos since the 1980s, the number of annual deaths held steady for more than a decade, because asbestos-related diseases may not strike victims for decades after they were exposed to these dangerous mineral fibers.

From 1999 to 2013, the years for which data are currently available, we have estimated the number of deaths from asbestos exposure in the U.S. at 189,000 to 221,000 people, or 12,000 to 15,000 deaths a year (Figure 1). Those figures are based on a review of federal records of deaths from diseases caused exclusively by asbestos, plus a calculation using a formula developed by international cancer researchers to estimate the number of lung cancer deaths likely caused by asbestos (CDC 2015, McCormack 2012).

Asbestos kills 12,000 to 15,000 Americans each year

Source:  Environmental Working Group.  Asbestosis and Mesothelioma deaths compiled from CDC WONDER database, 1999-2013.  Estimates of lung cancers attributed to asbestos exposure from McCormack 2012 study.

A more exact number can’t be pinned down, because asbestos-related deaths are not precisely recorded or reported by public health authorities. Our estimate is conservative.

Asbestos exposure is not usually listed as a cause of death for lung cancer victims, even though researchers believe that many more people die of lung cancer triggered by asbestos than of other diseases exclusively associated with asbestos. Nor does our estimate account for undiagnosed diseases or errors on death certificates that result in misclassification of asbestos-related diseases.

Three major diseases are caused by inhalation of airborne asbestos fibers:

• Mesothelioma is a rare and always fatal cancer that strikes the mesothelium, a thin membrane lining the lungs, heart, chest cavity, gastrointestinal system and reproductive organs. Mesothelioma is primarily caused by exposure to asbestos (ACS 2015). For the purpose of this analysis all mesothelioma victims are presumed to have been exposed to asbestos at some point in their lives.

• Asbestosis is caused by inhaled asbestos fibers that lodge deep in the lungs, scarring the organs or triggering the growth of excess tissue, a condition known as fibrosis. Asbestosis makes breathing excruciatingly painful and often leads to death from lung or heart failure; the victim essentially suffocates. There is no known cure. Because its symptoms are similar to other respiratory diseases, asbestosis may not always be recorded as the cause of death.

• Lung cancer can be caused by inhalation of asbestos fibers. Estimating the number of lung cancer deaths attributable to asbestos exposure is difficult, since death certificates citing the cause of death as lung cancer do not indicate if the person had any exposure to asbestos. However, we estimate that many more people die of asbestos-related lung cancer than from mesothelioma or asbestosis.

Researchers believe that some cancers of the larynx, ovaries, stomach and colorectal area are triggered by asbestos exposure (NAS 2006). The number of cases is impossible to estimate based on existing evidence. It is likely fewer people die from these cancers than from mesothelioma, asbestosis or lung cancer.

EWG Action Fund searched the WONDER database of the U.S. Centers for Disease Control and Prevention, which currently holds Multiple Causes of Death files for all fatalities recorded for the years 1999 to 2013 (CDC 2015). We obtained data for deaths from mesothelioma and asbestosis.  Asbestosis is a non-cancer respiratory disease attributed to asbestos exposure. Because the files allow local health officials to record more than one cause of death, we counted all deaths for which mesothelioma or asbestosis is listed as the primary or contributing cause.

The data show that between 1999 and 2013, mesothelioma was listed as the cause of 39,870 deaths, or about 2,848 a year (ICD-10 code C45). Asbestosis was listed as the cause of 20,317 deaths, or about 1,451 a year (ICD-10 code J61). Both conditions are listed as the causes of 1,285 deaths, or about 92 people per year (Table 1).

Table 1: Mesothelioma and Asbestosis Deaths, 1999-2013

Source: Environmental Working Group. Compiled from CDC WONDER database, 1999-2013.

Asbestosis was recorded as the primary cause of death in the cases of 40 to 50 percent of asbestosis victims. In the remainder, asbestosis was recorded as a contributing cause. As a result, our estimates of asbestosis deaths are higher than those of the Centers for Disease Control, which counts only the primary cause of death (CDC 2008, Bang 2013).

Yet our estimates are still conservative, because some unknown number of deaths may have been attributed to pneumonia, other respiratory disease or lung fibrosis of unknown origin (Reynolds 2014). If doctors failed to ask patients about asbestos exposure, or if patients were unaware they had been exposed to asbestos, the death certificate would not mention asbestos as a cause.

Mesothelioma and asbestosis are only part of the devastation wrought by asbestos. Studies of people who worked with asbestos indicate that they have higher rates of lung cancer as well. However, there has been little effort to tally the toll of asbestos-related lung cancer.

Most lung cancer in the U.S. results from cigarette smoking. Studies of smokers exposed to asbestos consistently find higher rates of lung cancer than among smokers who were not exposed (Moon 2013). The combination of asbestos exposure and smoking is particularly deadly.

The increased risk of lung cancer in a given group of people depends on how much they smoked and on the severity and timing of their asbestos exposure, making it difficult to estimate risks for the general population from a single study. Because asbestos is essentially the sole cause of mesothelioma, and mesothelioma risk is not influenced by smoking, many studies have attempted to estimate the number of asbestos-related lung cancer deaths based on the number of mesothelioma deaths.

Scientists at the International Agency for Research on Cancer, part of the United Nations’ World Heath Organization, reviewed 55 studies that reported the rates of both lung cancer and mesothelioma in groups of people exposed to asbestos (McCormack 2012). In a study published in 2012, these scientists suggest that the best way to estimate asbestos-related lung cancer in a population is based on the number of mesothelioma deaths for that group. Their analysis suggests that there are 3.2 to 4 lung cancer deaths in the U.S. for every mesothelioma death among individuals exposed to asbestos.

Applying this ratio to the Centers for Disease Control death certificate records for mesothelioma mortality, we calculated that between 1999 and 2013 an estimated 127,579 to 159,480 Americans died of lung cancer caused by asbestos exposure – about 8,500 to 10,600 deaths a year (Table 2). This suggests that asbestos-related deaths from lung cancer dwarfs both asbestosis and mesothelioma.

Table 2. Asbestos-related lung cancer deaths by year, 1999 to 2013

Source: Environmental Working Group.  Estimates of lung cancer deaths from asbestos exposure compiled from CDC WONDER data, 1999-2013 and McCormack 2012.

Still, the number of lung cancer deaths EWG Action Fund estimates with this method may also be too low, according to Richard Lemen, a former U.S. assistant surgeon general who now heads the Science Advisory Panel of the Asbestos Disease Awareness Organization. Dr. Lemen believes the number of lung cancer deaths would have been greater if the authors of the International Agency for Research on Cancer study had based their calculation on fewer and higher quality mortality studies (Lemen 2013). Indeed, a recent review of occupational studies found that studies with better data collection and longer followup of participants produced higher estimates of lung cancer deaths. (Lenters 2011, 2012).

Another review by the World Health Organization says the number of lung cancer deaths could be greater than the first study estimates. It says that in workers exposed to chrysotile, the most common type of asbestos, lung cancer deaths are six times higher than mesothelioma deaths (WHO 2014). If this were true for the U.S. population the number of asbestos-related lung cancer deaths would be much greater than we estimate. More research is urgently needed to clarify the asbestos-related lung cancer burden for Americans.

All told, when annual deaths from lung cancer, mesothelioma and asbestos are tallied, the scale of asbestos mortality is staggering. We calculate that from 1999 to 2013, between 11,586 and 15,510 Americans died each year from asbestos-related diseases. Over this period there was no apparent decline in asbestos deaths. For those who were exposed years ago but may not yet show symptoms, the prognosis is grim, although research to find a mesothelioma cure continues. To keep even more victims from exposure, suffering and death, the nation needs a total ban on asbestos.

References:

American Cancer Society. 2015. Asbestos. http://www.cancer.org/cancer/cancercauses/othercarcinogens/intheworkplace/asbestos

Bang KM, Mazurek JM, Wood JM, et al. 2014. Diseases Attributable to Asbestos Exposure: Years of Potential Life Lost, United States, 1999-2010. American Journal of Industrial Medicine. 57:38-48.

CDC. 2015. Wide-ranging Online Data for Epidemiologic Research (WONDER), Multiple Causes of Mortality files. Center for Disease Control, http://wonder.cdc.gov/mcd.html, queried March 2015.

CDC. 2008. Asbestosis-Related Years of Potential Life Lost Before Age 65 Years – United States, 1968–2005. Centers for Disease Control, Morbidity and Mortality Weekly Report. 57(49):1321-1325. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5749a1.htm

Lemen R, Frank AL, Soskolne CL, Weiss SH, Castleman B. 2013. Comment on ‘Estimating the asbestos-related lung cancer burden from mesothelioma mortality’ – IARC and Chrysotile Risks. British Journal of Cancer 109:823-825.

Lenters V, Vermeulen R, Dogger S, et al. 2011. A Meta-analysis of Asbestos and Lung Cancer: Is Better Quality Exposure Assessment Associated with Steeper Slopes of the Exposure–Response Relationships? Environ Health Perspect. 119(11):1547–1555.

Lenters V, Burdorf A, Vermeulen R, et al. 2012. Quality of Evidence Must Guide Risk Assessment of Asbestos. Ann Occup Hyg. 56(8):879-87

McCormack V, Peto J, Byrnes G, Straif K, Boffetta P. 2012. Estimating the asbestos-related lung cancer burden from mesothelioma mortality. British Journal of Cancer. 106:575-584.

Moon EK, Son M, Young-Woo J, et al. 2013. Variations of Lung Cancer Risk from Asbestos Exposure: Impact on Estimating of Population Attributable Fraction. Industrial Health. 51:128-133.

National Academy of Sciences. 2006. Asbestos: Selected Cancers. June 2006. https://www.iom.edu/Reports/2006/Asbestos-Selected-Cancers.aspx

Reynolds C, et al. 2014. Occupational lung disease: Idiopathic Pulmonary Fibrosis, Mesothelioma, and Asbestosis Mortality Trends For England And Wales: Is Asbestos Exposure Associated With IPF? Thorax 2014;69:A4-A5 doi:10.1136/thoraxjnl-2014-206260.9

Selikoff IJ, Churg J, Hammond EC. 1964. Asbestos Exposure and Neoplasia. Journal of the American Medical Association. 188:22-6.

WHO. Chrysotile Asbestos. 2014. World Health Organization. March 2014. http://www.who.int/ipcs/assessment/public_health/chrysotile_asbestos_summary.pdf