Teratogenic and Embryotoxic Effects of the Herbicides Di- and Trichlorophenoxyacetic Acids (2, 4D and 2, 4, 5-T)

Abstract: Commercial solutions of phenoxyacetic acids were tested for teratogenic effects in NMRI-mice. The Swedish product Hormoslyr 500-T contained only 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) while Hormoslyr 64 was a mixture of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-T (2:1). Subcutaneous injections were given from day 6 through day 14 of pregnancy and the animals were sacrificed on day 18. The number of resorbed embryos, living embryos with gross malformations, as well as internal and skeletal malformations were recorded. It was found that both preparations at the high dosage (110 mg/kg/day) were teratogenic and embryotoxic. At the low dose level (50 mg/kg/day) the 2,4,5-T solution was more harmful than the mixture of 2,4-D and 2,4,5-T. The risks of teratogenicity in human civilian use and the role of dioxins are discussed.