ABSTRACT
The insecticide synergist piperonyl butoxide--alpha-[2-(2-butoxyethoxy)ethoxy]-4,5-methylenedioxy-2-propyltoluene--was tested for carcinogenicity in inbred F344 rats in a 2-year study employing doses of 10,000 and 5,000 ppm of the compound administered continuously in the feed. Although a statistically significant dose-related increase in the incidence of lymphoreticular neoplasia was associated with administration of the compound to females, the incidence of that class of neoplasm was higher in control males than in treated males. The finding of statistical significance in one sex is not considered by itself to constitute sufficient evidence of a biologic effect to justify an indictment of carcinogenic action. However, inasmuch as the chief use of this substance is to alter the in vivo metabolism of other chemicals, its possible role as a cocarcinogen should be carefully considered in any risk-benefit evaluation aimed at setting policies regarding its uses.
Subject(s)
Carcinogens , Neoplasms, Experimental/chemically induced , Piperonyl Butoxide/toxicity , Animals , Drug Evaluation, Preclinical , Female , Leukemia, Experimental/chemically induced , Leukemia, Experimental/pathology , Lymphoma/chemically induced , Lymphoma/pathology , Male , Piperonyl Butoxide/administration & dosage , Rats , Rats, Inbred F344 , Sex FactorsABSTRACT
The long-term administration of 50 and 100 ppm of Mirex in the diets of male and female Charles River CD rats was associated with a spectrum of liver lesions, from foci or areas of cellular alteration and neoplastic nodules to hepatocellular carcinoma. Statistically significant numbers of neoplastic nodules were observed in the livers of male rats receiving the high dose. Neoplastic nodules and hepatocellular carcinomas were not observed in control rats.
