Inhibition of development of preneoplastic lesions in the livers of rats fed a weakly carcinogenic environmental contaminant.

The effects of di(2-ethylhexyl)phthalate (DEHP), a widely used plasticizer and environmental contaminant, on the emergence of gamma-glutamyltrans-peptidase positive (GGT+) preneoplastic foci in the liver was investigated. Sprague--Dawley male rats initiated with diethylnitrosamine (DEN) following partial hepatectomy were placed on: (1) a choline supplemented diet (CS); (2) a CS diet containing 2% DEHP (CS + DEHP); (3) a choline deficient diet (CD); (4) a CD diet containing a 0.06% phenobarbital (CD + PHB); or (5) a CD diet containing 2% DEHP (CD + DEHP). Rats maintained on the CS + DEHP diet for 5 and 10 weeks showed no increase in GGT + foci. The plasticizer effectively inhibited the appearance of the preneoplastic foci when it was included with the CD diet.