Comparative rates of elimination of some individual polychlorinated biphenyls from the blood of PCB-poisoned patients in Taiwan

Abstract

In 1979, a mass outbreak of poisoning occurred in Central Taiwan due to the ingestion of rice-bran oil contaminated with polychlorinated biphenyls (PCBs). The major PCB isomers and congeners in the toxic rice oil and in the blood of PCB-poisoned patients were characterized by gas chromatography and gas chromatography/mass spectrometry using a highly efficient glass capillary column. The elimination of some major individual PCBs from blood of these patients was studied. The results indicate that tetra- and pentachlorobiphenyls with adjacent unsubstituted carbon atoms at metapara positions are rapidly eliminated from the blood of patients, while PCBs with the same degree of chlorination but with adjacent unsubstituted carbon atoms at ortho-meta positions are eliminated more slowly. The results also indicate that most of the hexa- and heptachlorobiphenyls, with adjacent unsubstituted carbon atoms at ortho-meta positions of the biphenyl ring, are eliminated very slowly. Laboratory-animal studies have indicated that PCB excretion depends primarily on the rate of metabolism; therefore these differences in rates of elimination of PCBs should reflect the differences in their rates of metabolism.