Relative hepatotoxicity of some industrial solvents after intraperitoneal injection or inhalation exposure in rats

Intraperitoneal LD50 (lethal dose 50% kill) values and minimal liver toxic doses in female Sprague-Dawley rats were determined for the following industrial solvents: toluene, methylene chloride, carbon tetrachloride, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, ethanol, methyl ethyl ketone, and dioxane. For the following solvents LC50 values and minimal liver toxic air concentrations were also determined: xylene, styrene, chloroform, tetrachloroethylene, and dimethylformamide (DMF). The serum activity of the enzyme sorbitol dehydrogenase (SDH) was used as an indicator of liver damage. Carbon tetrachloride, chloroform, and DMF were hepatotoxic in low doses compared to LD50 values (TD50 (toxic dose 50%) values approximately 30, 90, and 50 mg/kg). Chloroform and DMF were hepatotoxic in comparatively low concentrations after a 4-hr inhalation exposure (TC50 (toxic concentration 50%) values approximately 590 and 740 mg/m3). Even relatively high doses of the other solvents did not raise the SDH activity. Significant direct (metabolite-mediated) hepatotoxicity seems to be an uncommon feature among commonly used industrial solvents.