Abstract
The estimated occupational ethylene oxide (EO) exposure concentrations corresponding to specified extra risks are calculated for lymphoid mortality as the most appropriate endpoint, despite the lack of a statistically significant exposure–response relationship. These estimated concentrations are for occupational exposures—40 years of occupational inhalation exposure to EO from age 20 to age 60 years. The estimated occupational inhalation exposure concentrations (ppm) corresponding to specified extra risks of lymphoid mortality to age 70 years in a population of male and female EO workers are based on Cox proportional hazards models of the most recent updated epidemiology cohort mortality studies of EO workers and a standard life-table calculation. An occupational exposure at an inhalation concentration of 2.77 ppm EO is estimated to result in an extra risk of lymphoid mortality of 4 in 10,000 (0.0004) in the combined worker population of men and women from the two studies. The corresponding estimated concentration decreases slightly to 2.27 ppm when based on only the men in the updated cohorts combined. The difference in these estimates reflects the difference between combining all of the available data or focusing on only the men and excluding the women who did not show an increase in lymphoid mortality with EO inhalation exposure. The results of sensitivity analyses using other mortality endpoints (all lymphohematopoietic tissue cancers, leukemia) support the choice of lymphoid tumor mortality for estimation of extra risk.
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Abbreviations
- Dow:
-
Dow Chemical Company
- EO:
-
Ethylene oxide
- IARC:
-
International Agency for Research on Cancer
- NIOSH:
-
National Institute for Occupational Safety and Health
- SMR:
-
Standardized mortality ratio
- UCC:
-
Union Carbide Corporation
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Acknowledgments
This manuscript is based on a December 16, 2010, slide presentation requested by the Scientific Committee on Occupational Exposure Limits (SCOEL). This work was financially supported by the CEFIC Ethylene Oxide & Derivatives Sector Group, Avenue Van Nieuwenhuyse 4, Box 2, B-1160 Brussels. The conclusions are those of the authors. The epidemiological data for the updated NIOSH study were obtained from the National Institute for Occupational Safety and Health through a Freedom of Information Act request (May 13, 2004). The epidemiological data for the updated UCC study were obtained under a November 19, 2008, confidentiality agreement between Union Carbide Corporation and Sielken & Associates Consulting, Inc.
Conflict of interest
The authors have served as EO consultants to the American Chemistry Council (ACC) and the European Chemical Industry Council (CEFIC). Statements of fact and opinion are those of the authors.
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Valdez-Flores, C., Sielken, R.L. & Jane Teta, M. Quantitative cancer risk assessment for ethylene oxide inhalation in occupational settings. Arch Toxicol 85, 1189–1193 (2011). https://doi.org/10.1007/s00204-011-0669-2
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DOI: https://doi.org/10.1007/s00204-011-0669-2