[Toxic effects of PCB/PCDF to human observed in Yusho and other poisonings]

Yusho PCB poisoning occurred in 1968, when the human environment had been polluted with PCBs and related compounds. The causal rice oil was contaminated with large amounts of PCBs and PCDFs by accidental leakage at the rice oil producing Kanemi Company on February 7-15, 1968. Much less concentrations of PCBs were identified in the rice oil produced and shipped from the Company before and after the critical days. Concentration trend of PCBs and TEQ in human body were examined for 40 years from 1968 to present. Concentrations in the blood of heavily exposed Yusho patients and normal Japanese were PCBs : 80 and 1.5 microg/g-fat, and TEQ : 60 and 0.1 ng/g-fat, respectively, in 1969, and decreased to PCBs : 1 and 0.2 microg/g-fat, and TEQ : 0.5 and 0.02 ng/g-fat, respectively, in 2007. PCBs and PCDFs have been persistently retained in human body for 40 years. Serious cases of Yusho and Yucheng having very high PCB, PCDF concentrations in blood have suffered from severe chloracne, pigmentation, eye discharge and others at the first stage and recovered very slowly with a lapse of several years. However, their hormone mediated signs and symptoms, such as high triglyceride and thyroxin levels in serum, disorder of immunoglobulin, goiter, decrease of sperm mobility, disorder of teeth and joints conditions, decrease of IQ score in children, headache and numbness, etc, are persisting for more than 30 years. The residents in East Slovakia who have been exposed to PCBs wasted from a PCB factory and have about 3 times higher blood PCB concentrations than the controls, have suffered from disorder of FT4 and T3 levels in serum, disorder of thyroid grand and thymus, dental defects in enamel developmental, hearing impairment at low frequency tone, tendency to diabetes and others. Residents in the Great Lakes area, USA, whose blood PCB levels are estimated to be higher than other places, have shown disorder of thyroid, T4, TSH levels, endometriosis, joint disorder, and low IQ score in children. The levels of PCBs and PCDFs in the blood of Yusho patients and Controls are compared to the normal levels of estradiol, testosterone and thyroxin. In the blood of Yusho patients, concentrations of single congeners of PCB118, PCB153, PCB156 and PentaCDF are high enough to disturb the hormonal effects. Blood PCB concentrations in normal Japanese are higher than the FT3 and FT4 levels, indicating hormonal disturbance will be easily produced. PCBs are metabolized to produce HO-PCBs, which bind to TTR and retain in blood medium. Blood HO-PCB concentrations in Yusho patients and normal persons are higher than the FT3, FT4 levels in serum. Therefore, the hormonal effects of thyroxin will be disturbed in Yusho and normal persons. As HO-PCB will be easily transferred to fetus through placenta, fetus development will be possible to be disturbed. In Yusho and other cases, PCBs and TEQ (PentaCDF, PCB118 etc) were ingested together and the strong enzyme inducers of PentaCDF and others have metabolized PCBs to HO-PCBs, which have retained in the blood. Complex reactions of PCDFs, PCBs and HO-PCBs have disturbed the hormonal effects and the induced symptoms and diseases would have been caused.