Development and viability of offspring of male mice treated with chlorinated phenoxy acids and 2,3,7,8-tetrachlorodibenzo-p-dioxin.

Male C57BL/6 mice were given feed containing various concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) such that their diets contained daily doses of approximately 40 mg/kg 2,4,-D, 40 mg/kg 2,4,5-T, and 2.4 micrograms/kg TCDD (group II); 40 mg/kg 2,4-D, 40 mg/kg 2,4,5-T, and 0.16 microgram/kg TCDD (group III); or 20 mg/kg 2,4-D, 20 mg/kg 2,4,5-T, and 1.2 micrograms/kg TCDD (group IV). Controls (group I) were given a diet with only the corn oil vehicle added to the feed. At the conclusion of an 8-wk dosing period, treated males cohabited with untreated virgin C57BL/6 female mice. Females were randomly assigned either to undergo teratological examination at 18 d of gestation, when the fetuses were examined for external, visceral, and skeletal malformations, or to be segregated and allowed to deliver their pups. Live and dead offspring and birth weight were recorded and viability was monitored until postnatal d 21. In both cases, development and survival of offspring in the test groups, whose sire had been treated with the mixture of phenoxy acids and TCDD, were not significantly different from those in the control group, whose sire had received untreated feed.