A mass poisoning involving at least 1,860 individuals occurred in Kyushu, western Japan, in 1968. The incident is called Yusho oil disease because it was caused by the ingestion of rice bran oil that was contaminated with Kanechlor-400, a commercial brand of Japanese polychlorinated biphenyls (PCBs). It was later found that the rice bran oil had been contaminated not only with PCBs but also with polychlorinated dibenzofurans (PCDFs), polychlorinated quaterphenyls (PCQs), and other related compounds. Yusho is thus recognized as poisoning by a mixture of PCBs, dioxins and related compounds. For more than 35 years the patients with Yusho have suffered from various symptoms such as general malaise, headache, acneform eruption, dark-brownish nail pigmentation, increased discharge from the eyes with swelling of the eyelids, pigmentation of oral mucosa, peripheral neuropathy, irregular menstruation in women, and growth retardation in infants and children. We hereby publish the supplement entitled “Long-term effects of polychlorinated biphenyls and dioxins in humans
- Lessons from Yusho”. We hope the issue will help our understanding of intoxication with PCBs and dioxins in humans.

Masutaka Furue
Department of Dermatology, Kyushu University, Maidashi 3-1-1,
Higashi-ku, Fukuoka, 812-8582, Japan
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