DOSE-RESPONSE RELATIONSHIP BETWEEN TOTAL CADMIUM INTAKE AND METALLOTHIONEINURIA USING LOGISTIC-REGRESSION ANALYSIS

The dose-response relationship for environmental cadmium exposure was assessed using logistic regression analysis. The prevalence of metallo thioneinuria was employed as a response variable, while age and total cadmium intake, calculated from the average cadmium concentration in r ice and duration of residence in the cadmium-polluted area, were used as explanatory variables. The target population comprised of 1843 cadm ium-exposed and 240 non-exposed inhabitants of Ishikawa, Japan. The in dividuals were divided into 96 subgroups by sex, age (4 categories), c admium concentrations in rice (3 categories) and length of residence i n the polluted area (4 categories). Only total cadmium intake had a si gnificant association with the prevalence of metallothioneinuria. In t he non-exposed subjects total cadmium intakes corresponding to 2.5% pr evalence of metallothioneinuria were calculated. Based on metallothion ein levels expressed as either mug/l urine or mug/g creatinine, the to tal intakes were: 2.221 or 2.207 g in men and 2.365 or 0.319 g in wome n, respectively. Most of these values were similar to those reported b y us previously, employing simple regression analysis. It is concluded , therefore, that a maximum allowable intake of about 2 g cadmium is a reasonable estimate for preventing the cadmium-induced renal dysfunct ion.