Archives of Toxicology

, Volume 85, Issue 10, pp 1189–1193 | Cite as

Quantitative cancer risk assessment for ethylene oxide inhalation in occupational settings

  • Ciriaco Valdez-Flores
  • Robert L. SielkenJr
  • M. Jane Teta
Regulatory Toxicology


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.


Ethylene oxide Excess cancer risk calculation for occupational inhalation exposure NIOSH and UCC epidemiology data Cox proportional hazards models Lymphoid mortality 



Dow Chemical Company


Ethylene oxide


International Agency for Research on Cancer


National Institute for Occupational Safety and Health


Standardized mortality ratio


Union Carbide Corporation

Supplementary material

204_2011_669_MOESM1_ESM.pdf (88 kb)
Supplementary material 1 (PDF 87 kb)


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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Ciriaco Valdez-Flores
    • 1
  • Robert L. SielkenJr
    • 1
  • M. Jane Teta
    • 2
  1. 1.Sielken & Associates Consulting Inc.BryanUSA
  2. 2.Exponent Health SciencesMiddleburyUSA

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