Three industrial solvents investigated for tumor promoting activity in the rat liver.

Dioxane, perchloroethylene, and trichloroethylene were investigated as rat liver altered foci promoters in an initiation/promotion protocol. Animals were initiated with diethylnitrosamine, 30 mg/kg, injected i.p. 24 h after 2/3 partial hepatectomy. The chemical under study was administered by gavage once a day, 5 times a week for 7 weeks. Ten days after the last administration the animals were killed. Liver sections were stained for gamma-glutamyl-transpeptidase (GGT) and the number and total volume of GGT-positive foci was studied. Dioxane (1000 mg/kg) significantly increased the number and total volume of foci while a marginal effect was noted for the high dose of trichloroethylene (1100 mg/kg). A high dose of perchloroethylene (1100 mg/kg) had no effect.