Polychlorinated biphenyls, dibenzofurans, and quaterphenyls in the toxic rice-bran oil and PCBs in the blood of patients with PCB poisoning in Taiwan.

A mass outbreak of poisoning occurred in central Taiwan in 1979 due to the ingestion of rice-bran oil contaminated with polychlorinated biphenyls (PCBs). In addition to PCBs, polychlorinated dibenzofurans (PCDFs) and polychlorinated quaterphenyls (PCQs) were also found in the contaminated oil. The levels of toxic agents in the rice-oil samples collected from factory and school cafeterias and the families of the intoxicated patients were in the range of 53-99 ppm, 0.18-0.40 ppm, and 25-53 ppm for PCBs, PCDFs, and PCQs, respectively. Major components of PCBs and PCDFs in the toxic oil were separated and identified by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) using glass capillary columns. The most toxic PCB reported in commercial PCB preparations, 3,4,3',4'-tetrachlorobiphenyl, was found in the toxic oil as well as in one of the patients' blood and adipose tissue at an early stage of poisoning. The blood samples of 165 patients collected 9 to 18 months after the onset of poisoning contained 10 to 720 ppb of PCBs with a mean value of 38 ppb. One of the most toxic PCDFs, 2,3,4,7,8-pentachlorodibenzofuran, was retained in the liver of a deceased patient. This compound could play an important role in the etiology of PCB poisoning in Taiwan.