Teratologic evaluation of 3,6-Dichloropicolinic acid in rats and rabbits.

3,6-Dichloropicolinic acid (clopyralid), a new herbicide, was evaluated for teratogenic potential in Fischer 344 rats and New Zealand White rabbits. Rats were given 0, 15, 75, or 250 mg clopyralid/kg/day by gavage on Days 6-15 of gestation while rabbits were given 0, 110, or 250 mg clopyralid/kg/day on Days 6-18 of gestation. Maternal toxicity, as evidenced by decreased body weight gain, was observed among pregnant rats in the 250-mg/kg/day group. No evidence of maternal toxicity was observed among treated rabbits. A teratogenic effect was not detected in either species.