DOC 040 – Comments on Recommendation from Scientific Commitee on Occupational Exposure Limits for 1,3-Butadiene

DOC 040 : Comment on Recommendation from Scientific Committee on Occupational Exposure Limits for 1,3-Butadiene | October 2000

The present document reviews the Recommendation on Occupational Exposure Limits for 1,3-butadiene (BD), developed by the Scientific Committee for Occupational Exposure Limits (SCOEL) to Chemical Agents, document SCOEL/SUM/75E, June 1999. Since ECETOC submitted its original criteria document on BD to SCOEL, significant new information has become available. This includes an update of the most relevant epidemiology study of styrene-butadiene rubber (SBR) workers, with improved cell type information and refined chemical exposure estimates. The most critical findings were that BD exposures were underestimated at least 5-fold in the original report, and, although there was an association between estimated cumulative BD exposure and leukaemia, it was present only at relatively high BD exposures, above 100 ppm. New biomarker studies demonstrate that BD is not genotoxic to workers at relevant occupational exposures, and additional information on the role of dimethyldithiocarbamate (DMDTC) in leukaemogenesis supports the biological plausibility of DMDTC as a potential confounding agent in the epidemiology studies. The ECETOC Task Force believes that the new information is vital to the development of a sound assessment and should be taken into account when preparing a scientifically based Occupational Exposure Limit for BD.