An outbreak of PCB poisoning

An outbreak of poisoning, characterized clinically by hyperpigmentation and a chloracne-like eruption, broke out in mid-Taiwan in February 1979. Probably over a thousand persons were affected. The source of poisoning was found to be a specific brand of rice bran oil which was contaminated accidentally with polychlorinated biphenyls (PCB). PCB was detected from suspected oil samples in concentrations of 40 to 106 ppm. The blood PCB levels were 70 to 460 ppb in some patients. The amount of oil consumed by the individual patients was approximately one liter per month. A total of 358 cases of suspected rice bran oil poisoning was seen in the special clinics of the Provincial Taichung Hospital and National Taiwan University Hospital. There were 171 males and 187 females, aged between 7 days and 78 years. Half of the patients were aged 11 to 30 years. One hundred and twenty-three patients were from families and the rest were groups from Hwei-Ming Blind School, factories, and temples. In general, the age distribution of the patients, the symptomatology, the skin pathology and the way the poisoning occurred were similar to those of Yusho patients. However, differences were noted in some clinical signs, namely a higher incidence of hyperpigmentation and a lower incidence of acneform eruption in our series when compared with Goto's series. It is speculated that this may be partly due to different isomers or concentrations of PCB in the blood and tissues.