© 1996 Oxford University Press
research-article |
Comparative Subchronic Studies on 2,4-Dichlorophenoxyacetic Acid, Amine, and Ester in Rats1
*Charles, Conn, & van Gemert, LLC Durham, North Carolina 27705
Rhone-Poulenc Ag Company Research Triangle Park, North Carolina 27705
John Wise & Associates, Ltd. Liberry, Missouri 64068
§Dow Chemical Company Midland, Michigan 48674-0001
Received December 19, 1995; accepted May 18, 1996
Forms of 2,4-dichlorophenoxyacetic acid (collectively known as 2,4-D) are herbicides used to control a wide variety of broadleaf and woody plants. Subchronic toxicity studies in rats were conducted on three forms of 2,4-D: the parent form, 2,4-D acid; 2,4-D dimethylamine salt (DMA); and 2,4-D 2-ethylhexyl ester (2-EHE). Doses in the subchronic studies (on an acid equivalent basis) were 0, 1, 15, 100, and 300 mg/kg/day. Major treatment related findings in the three studies included decreases in red cell mass, decreases in T3 and T4 levels, decreases in ovary and testes weights, increases in liver, kidney, and thyroid weights, and cataracts and retina] degeneration (high-dose females). These data demonstrated the comparable toxicities of 2,4-D acid, DMA, and 2-EHE and support a subchronic no-observed-effect level of 15 mg/kg/day for all three forms. In summary, the findings of these studies indicate comparable low subchronic toxicity potentials among representative forms of 2,4-D.