Effect of toluene inhalation on the liver of rats--dependence on sex dose and exposure time.

: Groups of CFY rats were exposed to toluene inhalation as follows: both males and females to 1000 mg/m3 6 h daily five times a week for 6 months; only males to 3500 mg/h3 8 h daily every day for 6 months; and only males to 1500, 3000 and 6000 mg/m3 8 h daily for 4 weeks. Control groups were exposed to air inhalation under identical conditions. Toluene was found to inhibit growth but to cause no abnormal light-microscopical changes. Hepatic changes were: (i) Signs of compensation such as increased relative liver weight, SER proliferation; increased succinate dehydrogenase activity; a decrease in glycogen content; increased cytochrome P-450 and b5 concentration; increased hepatic aniline hydroxylase and aminopyrine N-demethylase activity. (ii) Non-specific subcellular effect was observed in a small number of hepatocytes, namely RER dilatation, separation of ribosomes, mitochondria of variable shapes, an increased number of autophagous bodies. As regards indicators of the hepatic function, BSP retention decreased, GOT and GPT activity did not change. The changes were observed in both sexes, were dose-dependent and reversible, and showed no--or only a slight--dependence on exposure time. Chronic toluene exposure has no specific hepatotoxic effect leading to chronic liver disease.