Documents Smith, Randall 4 results

"Objectives The purpose of this study was to evaluate empirically the relevance of animal-bioassay-based models for predicting human risks from exposure 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 and environmental exposures to BD and to compare these estimates with those previously derived from an analysis of animal bioassay data.Results The estimates of risk were found to be highly dependent on the model used when low levels of exposure were evaluated that are of environmental concern, but not at the levels of occupational concern. For example, at the level (1 part per million) of the recently revised standard of the Occupational 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 the risk estimates derived from the epidemiologic models was remarkably similar to the range of risk estimates for occupational exposures (1 to 9 per thousand) 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."

Several quantitative risk assessment models have been published for occupational and environmental exposures to diesel exhaust particles (DEP). These risk assessment models are reviewed and applied to predict lung cancer risks for miners exposed to DEP. The toxicologically based unit risk estimates varied widely (from 2 to 220 ? 10-6 per g/m3). The epidemiologically based unit risk estimates were less variable and suggest higher risks (from 100 to 920 ? 10-6 per g/m3). The wide range of risk estimates derived from these analyses reflects the strong assumptions and large uncertainties underlying these models. All of the models suggest relatively high risks (i.e., >1/1,000) for miners with long-term exposures greater than 1,000 g/m3. This is not surprising, given the fact that miners may be exposed to DEP concentrations similar to those that induced lung cancer in rats and mice, and substantially higher than the exposure concentrations in the positive epidemiologic studies.