Excretion of urinary cadmium, copper, and zinc in cadmium-exposed and nonexposed subjects, with special reference to urinary excretion of β2-microglobulin and metallothionein

The objectives of this study were to examine the association between urinary excretion of cadmium (U-Cd), copper (U-Cu), and zinc (U-Zn) and the severity of two different indicators of renal toxicity (urinary excretion of beta(2)-microglobulin [U-(beta(2)-MG] and metallothionein [UMT]) in Cd-exposed subjects compared to controls, and to assess the physiologic mechanisms by which the exposure to environmental Cd affects U-Cd, U-Cu, and U-Zn. The target population included 3508 Cd-exposed and 294 nonexposed participants who received a health survey conducted among the population of the Kakehashi River basin. Increases of U-Cd, U-beta(2)-MG, and U-MT in the Cd-exposed population were observed relative to excretion of these substances in controls. Regression analysis using a general linear model revealed that the correlations between U-Cd or U-Cu, and U-beta(2)-MG and between U-Cd, U-Cu or U-Zn, and U-MT were statistically significant in both sexes, but the correlation between U-Zn and U-beta(2)-MG excretion was significant only in men. These results suggest U-Cd and U-Cu is affected by dysfunction in renal tubular absorption (indicated by U-beta(2)-MG), whereas not only U-Cd and U-Cu but also U-Zn appear to be a function of renal cellular desquamation (indicated by U-MT).