Quantitative risk assessment of exposures to butadiene in EU occupational settings based on the University of Alabama at Birmingham epidemiological study

Abstract

The excess risks due to 1,3-butadiene (BD) inhalation in EU occupational settings are quantified for leukemia, AML, CLL, CML, lymphoid neoplasms, and myeloid neoplasms. The most recent data from the University of Alabama at Birmingham epidemiological study of North American workers in the styrene-butadiene rubber industry are modeled.The number of high-intensity tasks (HITs) and other exposure covariates may be more important predictors than cumulative BD ppm-years alone. For example, all of the 71 leukemia decedents in the UAB study who were exposed to BD had some BD HITs. None of the 1192 exposed workers without BD HITs had leukemia mortalities.The authors’ best estimate (consolidated over all endpoints) of the average occupational BD exposure concentration for 45years of exposure starting at age 20 corresponding to an added risk of 1/10,000 by age 70 is 7.2ppm.Cumulative BD ppm-years is not statistically significantly associated with CML, AML, or myeloid neoplasms or (after any one of eight exposure covariates is included in the modeling) leukemia. The statistical significance of the slopes for leukemia, CLL, and lymphoid neoplasms unadjusted for covariate effects disappears when modeling is restricted to person years with less than 200 cumulative BD ppm-years.