Overview of Yusho

Background: Yusho is a type of food poisoning from rice bran oil contaminated with polychlorinated biphenyls (PCBs) and various dioxins such as polychlorinated dibenzofurans (PCDFs). The victims of Yusho suffered from dermatological manifestations (acneform eruptions, comedones, etc.) in association with systemic, ophthalmological, and mucosal symptoms. Objective: To analyze the relationship between the concentrations of dioxins/PCBs and the subjective/objective complaints of patients with Yusho. Methods: We recently started to measure the blood levels of dioxins in the annual medical check-up of Yusho patients. In addition, we reviewed the clinical and epidemiological findings elucidated over the past 36 years by the Study Group for Yusho. Results and conclusion: High amounts of PCBs and PCDFs are still present in a number of patients with Yusho. The majority of laboratory findings, except for triglyceride concentration, were within normal limits throughout the clinical course. However, the patients still suffered from various mucocutaneous and subjective symptoms, and these symptoms were correlated to the blood levels of polychlorinated congeners. The development of therapeutic interventions is warranted in the near future.