PCBs and Interactions with Insecticides

The effects of polychlorinated biphenyl plasticizers, like those of many other environmental chemicals ("synthetic chemicals to which man is exposed by either voluntary or involuntary means"), on biological systems are not too well understood. When research by our group at the University of Wisconsin indicated in 1969 (1) that several of the Aroclor compounds increased the toxicity of DDT and dieldrin to insects, their potential biological interaction with environmental chemicals was indicated. Since then further studies were conducted in our laboratory to investigate the effects and interactions of environmental chemicals on human cells in tissue culture by determining the toxicity of some of these chemicals on HeLa cells and skin fibroblasts (2). Aroclor 1254 (a polychlorinated biphenyl plasticizer), carbaryl, parathion, DDT, several insecticide metabolites, aspirin and caffeine were used to determine their effects on cell growth and synthesis oI proteins and nucleic acids. The dosage causing a 50% inhibition in culture growth was determined, and the interaction or combined effects between these chemicals relative to their effects on protein and nucleic acid synthesis was studied. Both cell types responded nearly equally to the presence of an individual chemical. Aspirin and caffeine were 8 to 20 times less toxic than the other chemicals studied, while Arcolor 1254 was as toxic as DDT (Fig. 1). Parathion was more toxic than its metabolite paraoxon. Para-nitrophenol was as toxic as parathion. 1-Naphthol was less toxic than its parent compound carbaryl. The toxicities of DDT and DDE were dependent upon cell type. Little significant interaction on nucleic acid or protein synthesis was seen (2).