Butadiene and styrene are oxidized, in part, by eral blood. Butadiene and mixtures of butadiene cytochrome P450 2E1 and have been shown to and styrene were genotoxic in mice, as shown by metabolically interact in rodents exposed by inhala-a significant increase in the frequency of micronution to mixtures of both compounds. Because the cleated polychromatic erythrocytes. The increased reactive metabolites of butadiene and styrene are frequency following exposure to mixtures of butadithought to be responsible for the toxicity of each ene and styrene was not significantly different comcompound, metabolic interactions may alter the re-pared with the frequency following exposure to busponse in animals exposed to mixtures of butadiene tadiene alone. Styrene and mixtures of butadiene and styrene compared with the response in animals and styrene were cytotoxic in mice, as shown by exposed to butadiene alone or styrene alone. The significantly decreased number of spleen cells. Expurpose of this study was to quantitate alterations posure to mixtures of butadiene and styrene with in genotoxicity and cytotoxicity in male B6C3F1 butadiene concentrations of 62.5 or 625 ppm sigmice exposed to mixtures of butadiene and styrene. nificantly reduced the number of thymus cells. Expo-Male B6C3F1 mice were exposed to 6.25, 62.5, sure to 200 ppm or 625 ppm butadiene alone, or 200, or 625 ppm butadiene alone, 50 ppm styrene to mixtures of 200 ppm or 625 ppm butadiene and alone, or mixtures of 6.25, 62.5, 200, or 625 ppm 50 ppm styrene, significantly reduced the frequency butadiene and 50 ppm styrene. Genotoxicity was of polychromatic erythrocytes in the peripheral assessed by quantitating the frequency of micronu-blood. The results of the study demonstrate that excleated polychromatic erythrocytes in bone mar-posure to mixtures of butadiene and styrene does row. Cytotoxicity was assessed by counting total not reduce the respective genotoxicity of butadiene spleen and thymus cells and by quantitating the fre-or cytotoxicity of styrene.