Exposure of general Japanese population to cadmium and lead : A risk evaluation

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A nation-wide survey was conducted in 1990s in 19 sites in Japan as a follow-up of a preceding study conducted in 1980s. Altogether 467 women volunteered for blood sampling, of whom 375 subjects offered 24-hour total food duplicate samples in addition. Geometric mean (GM) cadmium in blood (Cd-B) in 1990s (1.98 ng/ml) were lower than Cd-B in 1980s (3.58 ng/ml), and Cd in food duplicates (Cd-F) was also lower in 1990s (30.0 ug/day) than in 1980s (38.0 ug/day). Lead in blood (Pb-B) and food (Pb-F) were 23.2 ng/ml and 7.1 ug/day in 1990s, being lower than the values for 1980s (33.9 ng/ml) and 32.2 ug/day). The observation shows a reduced Cd and Pb burden among general Japanese population. In a subsequent study, three urinary low-molecular-weight proteins of alpha_1-microglobulin (alpha_1-MG), beta_2-microglobulin (beta_2-MG) and retinol binding protein (RBP) were studied in 378 women in addition to Cd-F,Cd-B and cadmium in urine (Cd-U). When the subjects were classified into three groups of low (20.4 ug/day), middle (35.0 ug/day) and high (67.0 ug/day) Cd-F levels, there was no dose-dependent increase in alpha_--MG,beta_2-MG or RBP,although Cd-B and Cd-U increased in response to higher Cd-F.Thus it is prudent to conclude that no apparent Cd-induced kidney dysfunction could be detected among the general populations in Japan.