Symptoms and blood PCB level among chronic Yusho patients, twenty-five years after outbreak

To investigate the frequency of symptoms and signs and their relationships with blood PCB (polychlorinated biphenyls) levels, twenty-five years after outbreak we analyzed the data of 276 Yusho patients (male/female: 137/139) who had received health examination in 1993. For this purpose 31 examination items which correspond or relate to the diagnostic criteria for Yusho (1976) were selected from the examination form. Mean blood PCB concentration in the subjects was 4.09 ppb with the highest value of 31.0 ppb (median: 4.0 ppb). The symptoms for which the proportion exceeded 60% were general fatigue, headache and numbness in extremities. Chronic bronchitis- like symptoms, such as cough and sputum, were observed in 50% of the subjects. Next, the subjects were classified into approximate quartiles of blood PCB: <3.00, 3.00-4.06, 4.07-5.99, and 6.00 + ppb. The distributions of subjects at four levels of blood PCBs were compared between the groups with or without each symptom or sign, using the Cochran-Mantel-Haenszel test. Significant differences were observed for comedones in the trunk (P = 0.02) and other regions (P = 0.02); acneiform eruptions in the genital regions (P = 0.01) and gluteal regions (P = 0.01); and hypersecretion in the Meibomian gland (P = 0.04). Thus, the typical skin and eye symptoms in Yusho patients still persist showing a close relation with blood PCB concentration.