Antagonistic interactions of an arsenic-containing mixture in a multiple organ carcinogenicity bioassay

Inorganic arsenic (As), 1,2-dichloroethane (DCE), vinyl chloride (VC) and t richloroethylene (TCE) are frequently identified as groundwater contaminant s near hazardous waste disposal sites. While the carcinogenicity of each of these chemicals has been extensively studied individually, little informat ion exists regarding their carcinogenic potential in combination. Therefore , we investigated the carcinogenic promoting potential of chemical mixtures containing arsenic, DCE, VC and TCE following multiple initiator administr ation in a multiple organ carcinogenicity bioassay (N. Ito, T. Shirai, S. F ukushima, Medium-term bioassay for carcinogens using multiorgan models, in: N. Ito, Il. Sugano (Eds.), Modification of Tumor Development in Rodents, F rog. Exp. Tumor Res., 33, 41-57, Basel, Karger, 1991). Our results reveal a dose-responsive antagonistic effect of this four-chemical mixture on the d evelopment of preneoplastic hepatic lesions (altered hepatocellular foci an d glutathione S-transferase pi positive foci) as well as bronchioalveolar h yperplasia and adenoma formation. (C) 1998 Published by Elsevier Science Ir eland Ltd. All rights reserved.