AbstractMale CD‐1 mice were exposed to a commercial formulation of 2,4‐dichlorophenoxyacetic acid (2,4‐D), the amine derivative, in the drinking water at concentrations ranging from 0 to 0.163 of the formulated product, equivalent to approximately 0–50 mg kg−1day−12,4‐D content. The effect of 2,4‐D on urethan‐induced pulmonary adenoma formation was evaluated following a 105‐day exposure. Urethan‐induced sleeping times observed following an i.p. injection of urethan (1.5 mg g−1) after 3 weeks of 2,4‐D exposure were not altered by 2,4‐D, indicating that 2,4‐D did not influence urethan elimination. Pulmonary adenoma production, which was evaluated 84 days after urethan injection, was enhanced by 2,4‐D exposure but had no effect on tumor size. The effect of 2,4‐D on the incidence of spontaneous murine lymphocytic leukemia was evaluated during the 365‐day treatment period. Mortality associated with the leukemia virus was not altered by 2,4‐D treatment. Exposure to this commercial 2,4‐D product at moderately high levels of exposure may modify the development or expression of certain tumors in CD‐1 mice. The mechanism of the co‐carcinogenic or tumor‐promoting activity associated
展开▼
