Long-Term Health Effects of PCBs and Related Compounds: A Comparative Analysis of Patients Suffering from Yusho and the General Population

Yusho, which refers to a mass poisoning caused by the ingestion of rice bran oil contaminated with polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans, was first reported in October 1968 in Japan. Yusho patients suffer from various symptoms; however, after 40 years, some emerging symptoms have been attributed to aging. The prevalence of symptoms and diseases among Yusho patients and the general population was compared in this study. The data obtained from the survey among Yusho patients (1131 patients) by the Ministry of Health, Labour, and Welfare of Japan in 2008 were compared with the data from a survey conducted among the general population. When selecting the comparison group, the age and residential area (prefecture) were taken into account to match the baseline characteristics of Yusho patients. A logistic regression analysis was performed to identify the association between Yusho and the prevalence of symptoms and was adjusted for various potential confounding factors (age, sex, body mass index, cigarette smoking, frequency of drinking, and walking time). Skin pigmentation and acneiform eruption were found to be characteristic symptoms of Yusho and were more prevalent in these patients. Other symptoms and diseases associated with Yusho included orthostatic hypotension, hypohidrosis, dysgeusia, Basedow’s disease, hoarseness, cardiac insufficiency, tachycardia, eczema, and hair loss. Symptoms related to aging, such as general fatigue, arthralgia, and numbness in the extremities, were significantly higher in Yusho patients after adjusting for age and lifestyle. This study demonstrated that, 40 years after the outbreak of Yusho, the prevalence of various symptoms and diseases in Yusho patients, including age-related diseases, was higher than that in the general population.