The toxicity of tetrachlorobenzyltoluenes (Ugilec 141) and polychlorobiphenyls (Aroclor 1254 and PCB-77) compared in Ah-responsive and Ah-nonresponsive mice

The toxicity of the PCB substitute Ugilec 141, a mixture of tetrachlorobenzyltoluenes (TCBTs), is compared with the toxicity of a commercial mixture of polychlorobiphenyls (Aroclor 1254) and with the model toxic PCB-congener 3,3',4,4',-tetrachlorobiphenyl (PCB-77) as a positive control. Alterations in liver weight, hepatic cytochrome P450 content and EROD and PROD activity, plasma thyroxin and retinol level, hepatic retinoid level and liver and thyroid pathology, have been studied in Ah-responsive and Ah-nonresponsive mice. Ugilec 141 proved to induce similar toxicological changes, qualitatively and quantitatively, to Aroclor 1254. Therefore Ugilec may pose a similar environmental and health risk as PCBs. The criteria for acceptance of new substances, like Ugilec 141, on the European market are discussed.