Acrylonitrile Exposure at Work Associated with Significant Risk to Workers

July 15, 2024, by Jennifer K. Loukissas, M.P.P.

Acrylonitrile is used in the manufacturing of a wide range of products and materials including nitrile gloves, plastic toys, and plumbing materials. Experts in the Occupational and Environmental Epidemiology Branch (OEEB) have been studying workers making or using acrylonitrile since the 1980s. In the latest analysis of data from the NCI Acrylonitrile Cohort Study, a population of over 25,000 workers, they used a novel approach to correct for bias, assess the extent of worker mortality that results from exposure, and test hypothetical alternatives to the present regulatory limit of exposure, specifically for lung cancer mortality. Their findings were published in Occupational and Environmental Medicine on May 20, 2024.

Alexander Keil, Ph.D., M.S.P.H., Earl Stadtman investigator in OEEB, and colleagues, reported both that lung cancer mortality was higher among those who recently left employment and more highly exposed workers left employment more frequently. These findings indicate the potential for healthy worker survivor bias, which occurs when healthier workers tend to stay employed and exposed for longer periods of time than less-healthy colleagues but are also less likely to develop disease. Together, these observations suggest previous findings may have underestimated the association between acrylonitrile and lung cancer mortality.  

In this new analysis, the investigators estimated that over seven lung cancer deaths per 1000 workers by age 90 resulted from acrylonitrile exposure at work. If historical exposure limits had been at or below current international regulatory limits (in the U.S., 2.0 parts per million (ppm); and 0.45ppm in the European Union), relative to no intervention, reducing exposure to under 2.0, 1.0, and 0.45ppm, would have been expected to reduce lung cancer mortality by age 90 by 4.46, 5.03, and 6.45 deaths per 1000 workers, respectively.  

These findings, along with other papers from the NCI Acrylonitrile Cohort Study (references below), contributed to the recent classification by the Monograph Programme of the International Agency for Research on Cancer of acrylonitrile as carcinogenic to humans (Group 1) on the basis of sufficient evidence for lung cancer.  

References

Keil A et al. Estimating impacts of reducing acrylonitrile exposure on lung cancer mortality in an occupational cohort with the parametric g-formula. Occupational and Environmental Medicine. 2024. 

Koutros S et al. Extended mortality follow-up of a cohort of 25,460 workers exposed to acrylonitrile. Am J Epidemiol. 2019. 

Blair A et al. Mortality of industrial workers exposed to acrylonitrile. Scand J Work Environ Health. 1998.