A teratological evaluation and analysis of fetal tissue levels following administration of tetrachlorobenzene isomers to the rat

Abstract

Three tetrachlorobenzene (TCB) congeners (1,2,3,4‐, 1,2,3,5‐, and 1,2,4,5‐) were administered daily by gavage to pregnant Sprague‐Dawley rats at levels of 50, 100, or 200 mg/kg from day 6 through day 15 of gestation. Mothers were sacrificed on day 21 of gestation and the pups removed by cesarian section for teratological evaluation. Administration of 1,2,3,4‐ and 1,2,3,5‐TCB failed to alter maternal body weight, organ weights, hematological, or the biochemical parameters studied. The highest dose level of 1,2,4,5‐tetrachlorobenzene caused maternal death in nine of ten animals. In addition it induced mixed function oxidases and increased serum cholesterol values at 50 and 100 mg/kg. There was a decrease in the number of fetuses at the highest dose levels of 1,2,3,4‐ and 1,2,3,5‐TCB and at the lowest dose level of the 1,2,4,5‐ congener. None of the congeners produced any anomalies. There were no treatment‐related histopathological changes in either the mothers or fetuses. Residues of all three congeners were found in maternal and fetal tissues but generally the amounts of the 1,2,4,5‐ isomer were about 100 times higher than the other two.