Relationship between the amount of rice oil ingested by patients with yusho and their subjective symptoms

The goal of this study was to clarify the subjective symptoms closely related to yusho by examining the relationship between the amount of PCB-contaminated rice oil ingested by patients and the subjective symptoms recorded on their questionnaires. The amount of PCB-contaminated rice oil consumed by the patients was obtained by interviewing the housewife in each yusho family. Individual consumption of the oil was estimated by taking into account age, sex and the number of meals at home. In 1970, 46 patients were available for analysis, and in 1971, 33 patients were available. Among 12 subjective symptoms studied, numbness of the limbs, coughing, expectoration, and the sensation of "elevated" teeth were considered to show a dose-response relationship, which suggests that these subjective symptoms are closely related to yusho. Consistent high rates of complaints of general fatigue and eye discharge were considered possibly to be connected with yusho, although no dose-response relationships have been determined. Other subjective symptoms, such as fever, headache, dizziness, abdominal pain, swelling in the joints, changes in menstruation, and loss of hair failed to show consistent dose-response relationships. It should be noted, however, that for these symptoms which failed to show dose-response relationships, it is impossible to deny a causal relationship.