Styrene inhalation toxicity studies in mice. I. Hepatotoxicity in B6C3F1 mice

Studies were conducted to evaluate the toxic effects of short-term repeated styrene inhalation in B6C3F1 mice. Male and female mice were exposed to 0, 125, 250, or 500 ppm styrene, 6 hr/day, for up to 14 days. Styrene toxicity was characterized by severe centrilobular hepatic necrosis and deaths after one exposure to 500 ppm or two exposures to 250 ppm. Mortality and hepatotoxicity were not increased by additional exposures, and in surviving mice, regeneration and repair of initial hepatic injury occurred in spite of continued exposure for 14 days. A marked sex difference was observed, with male mice significantly more susceptible to styrene toxicity than females. A nonlinear dose response was observed where mortality in male and female mice was greater in the 250 ppm dose group than that in the 500 ppm dose group. Severe congestion and necrosis of the liver was present in moribund mice; hepatic congestion and serum alanine aminotransferase and sorbitol dehydrogenase were significantly greater in moribund animals.