Mutagenicity of PCBs and their pyrosynthetic derivatives in cell-mediated assay.

The mutagenicity of PCBs, Aroclor 1242 and Clophen A60 was studied in a mammalian cell assay using V79 Chinese hamster cells as target cells. The method was used as a direct assay without metabolizing cells and as a cell-mediated assay with 5000 R-irradiated rat fibroblasts as metabolizing cells. A wipe soot sample of a PCB fire was studied in the same assay, and the results showed no mutagenicity of the pure PCBs. However, the wipe sample showed weak mutagenic activity which disappeared when metabolizing cells were used. The chemical analysis of the wipe sample showed tri-, tetra- and pentachlorodibenzofurans in addition to PCBs.