BIOLOGICAL MONITORING FOR MUTAGENIC EFFECTS OF OCCUPATIONAL EXPOSURE TO BUTADIENE

The use of biological markers in the evaluation of human exposure to h azardous agents has increased rapidly in recent years. Because 1,3-but adiene is a mutagenic carcinogen, existing occupational levels of expo sure may be appropriately evaluated using somatic cell mutation as a b iomarker. Previously, we have described a biomarker study of workers i n a butadiene monomer plant (Ward et al., 1994). We now report results from a second study of the same group of workers, conducted after pla nt modernization, and present preliminary results from a study of expo sures in a styrene butadiene rubber (SBR) plant, Air levels of butadie ne were determined using either charcoal tubes with air pumps or passi ve badge dosimeters, The quantity of a butadiene metabolite in the uri ne was used as a biomarker of exposure and the mutagenic effects of ex posure were measured using the autoradiographic hprt mutant lymphocyte assay. in all three studies, the Frequencies of hprt mutants were sig nificantly elevated in workers from the areas of highest exposure when compared to workers from lower exposure areas or non-exposed subjects , The concentration of the urinary metabolite was significantly increa sed in high-exposed workers in the first study of monomer plant worker s but not in the second, In the first monomer plant study, historical air concentrations of butadiene were higher in the production units th an in the central control unit. While concurrent determined air concen trations were not elevated in the second monomer plant study, they wer e elevated in high exposure areas in the SBR plant study. Mutant frequ encies in the lower-exposure and the non-exposed groups were consisten t with historical values for non-smoking individuals who were not expo sed to known mutagens. The use of biomarkers, including the hprt mutan t lymphocyte assay, may be of great value in determining an appropriat e occupational exposure limit for butadiene.