Evaluation of the teratogenic potential of the oxidative dyes 6-chloro-4-nitro-2-aminophenol and o-chloro-p-phenylenediamine.

The oxidative dyes 6-chloro-4-nitro-2-aminophenol and o-chloro-p-phenylenediamine were administered by gavage to Sprague-Dawley rats on days 6-15 of gestation at dose levels of 87.5, 175 and 350 mg 6-chloro-4-nitro-2-aminophenol/kg body weight/day and 100, 200 and 400 mg o-chloro-p-phenylenediamine/kg/day. Maternal body-weight gain was significantly reduced by the high dose of each dye and the intermediate dose of o-chloro-p-phenylenediamine. Rats given the high dose of the latter dye showed a significant increase in resorptions and a significant decrease in foetal body weights. No embryotoxic or foetotoxic effects were observed with 6-chloro-4-nitro-2-aminophenol. Evaluation of foetuses for gross, visceral and skeletal anomalies revealed no statistically significant differences between dye-treated and vehicle-control groups but showed a significant increase (to 25-91%) in the incidence of abnormal foetuses in the group exposed to vitamin A, the positive control.