[Associations between blood PCB level and symptoms of Yusho patients, twenty years after outbreak]

To investigate relationships between blood PCB (polychlorinated biphenyls) level and symptoms of Yusho patients, twenty years after outbreak, a comparative study was designed in accordance with the results of medical examination conducted in 1988. For this examination, standardized forms were introduced in 1986, and a whole system for data-processing has been completed through two-years' efforts. Study subjects were 259 Yusho patients (male: 136, female: 123) for whom PCB concentration in blood was reported, among a total of 285 patients examined (91%). And 31 examination items which correspond or relate to the diagnostic criteria for Yusho (1976) were selected from the examination form for analysis. Mean blood PCB concentration in the subjects was 4.78 ppb ranging 0.6-32.0 ppb. The subjects were stratified for four blood PCB levels, less than or equal to 2.6 ppb; less than or equal to 4.0 ppb; less than or equal to 6.0 ppb; greater than 6.0 ppb, by dichotomized categories (normal/abnormal) for the results of each examination. This two-by-four table was transformed to two-by-two table with a cut-off point where the largest chi 2-value was obtained. Then the odds ratio (OR) adjusted for gender and age was calculated for the examination item which showed a statistically significant decrease or increase in crude odds ratio, to assess the association between blood PCB level and symptoms of Yusho patients. (ABSTRACT TRUNCATED AT 250 WORDS)