Toxicity of 1,2,3,4-, 1,2,3,5- and 1,2,4,5-Tetrachlorobenzene in the Rat: Results of a 90-Day Feeding STUDY

Abstract

Tetrachlorobenzenes (TCB) are industrial chemicals used as intermediates for chemical synthesis and for electrical insulation. TCB residues have been found in Great Lakes [USA, Canada] fish. The present study was designed to determine the subchronic toxicity of these compounds. Groups of 15 male and 15 female rats were fed diets containing 0, 0.5, 5.0, 50 or 500 ppm of 1,2,3,4-, 1,2,3,5- and 1,2,4,5-TCB for 13 wk. Rats fed 500 ppm 1,2,4,5-TCB exhibited significant increases in liver and kidney weight. 1,2,4,5-TCB at the highest dose level caused a significant increase in serum cholesterol levels. Hepatic microsomal aminopyrine demethylase and aniline hydroxylase activities were induced by this compound at 50 and 500 ppm in the males, and 500 ppm in the females. Moderate to severe histological changes occured in the liver and kidney of rats fed the 3 TCB isomers but the 1,2,4,5-isomer caused the most severe lesions. 1,2,4,5-TCB accumulated in fat and liver in a dose-dependent manner. 1,2,4,5-TCB was the most toxic isomer of the 3 and accumulated in liver and fat in a dose-dependent manner.