Comment on the carcinogenic potential of di(2-ethylhexyl) phthalate.

Analysis of the carcinogen bioassay of di(2-ethylhexyl) phthalate (DEHP) has shown that the designated maximum tolerated dose was exceeded in the low- and high-dose groups of male rats, in the high-dose group of female rats, and in the low- and high-dose groups of female mice. Significant differences in tumor incidence among small populations of laboratory animals within the testing facility further confounded interpretation of the bioassay. Critical data on food consumption, nutritional status, clinical signs, clinical pathology, and intestinal microorganisms are lacking. This review concludes that because of major deficiencies in the available data, the studies cannot be interpreted as showing a carcinogenic effect due to DEHP alone. Epigenetic mechanisms to explain the biologic effects are examined.