Human cancer risk and exposure to 1,3-butadiene - a tale of mice and men

Objectives The purpose of this study was to evaluate empirically the releva nce of animal-bioassay-based models for predicting human risks from exposur e to 1,3-butadiene (BD) using epidemiologic data. Methods Relative-risk results obtained with a regression model in a recent epidemiologic study were used to estimate leukemia risk for occupational an d environmental exposures to BD and to compare these estimates with those p reviously derived from an analysis of animal bioassay data. Results The estimates of risk were found to be highly dependent on the mode l used when low levels of exposure were evaluated that are of environmental concern, but not at the levels of occupational concern. For example, at th e level (1 part per million) of the recently revised standard of the Occupa tional Safety and Health Administration in the United States the estimates of lifetime excess risk ranged from 1 to 8 per 1000 workers. The range of t he risk estimates derived from the epidemiologic models was remarkably simi lar to the range of risk estimates for occupational exposures (1 to 9 per t housand) previously developed by Dankovic et al in 1993 from an analysis of a mouse bioassay study for lymphocytic lymphoma. Conclusions Results for BD seem to provide another example of a high degree of concordance between the risk predictions from models of toxicologic and epidemiologic data, particularly at occupational levels of exposure.