Concentrations of PCB congeners in sera from workers with past and present exposure

The isomers indicating occupational exposure to PCB have been identified as 2,4,4′-triCB (IUPAC 28), 2,4,4′,5-tetraCB (IUPAC 74), 2,3,4,4′-tetraCB (IUPAC 60) and 2,3′,4,4′-tetraCB (IUPAC 66)^1,2, and those indicating accidental (short term) exposure as 2,4,4′-triCB (IUPAC 28), 2′,3,4-triCB (IUPAC 33) and 2,3′,4,4′-tetraCB (IUPAC 66). The latter isomers also prevailed in continuous exposure in a hazardous waste disposal plant. Abnormal levels of these isomers predicted elevated concentrations of coplanars, non-ortho-chlorinated isomers (IUPAC 77, 81, 126 and 169). Among the non-ortho-chlorobiphenyls 3,3′-4,4′- and 3,4,4′,5-tetraCB concentrations were clearly elevated in exposed groups compared to Finnish referents. 3,4,4′,5-TetraCB levels were below the limit of detection in all referents, elevated concentrations were observed in both capacitor manufacture and hazardous waste disposal. Elevated concentrations of 3,3′,4,4′,5-PentaCB were detected in capacitor manufacture and in some workers in hazardous waste disposal. Elevated concentrations of 3,3′,4,4′,5,5′-hexaCB were observed in capacitor manufacture.