Reduced cadmium and lead burden in Japan in the past 10 years

Objective To investigate the current levels of exposure of the Japanese population to cadmium and lead, in comparison with the levels in 1980s. Design A nation wide survey was conducted in 1991-1994 (the 1990 study) in 19 study sites in Japan as a follow-up to a study conducted in 1979-1983 (the 1980 study). Blood samples and 24-h total food duplicates were collected from women who did not smoke or drink habitually. Methods Blood and food duplicates (after homogenization) were analysed for cadmium (Cd-B and Cd-F, respectively) and lead (Pb-B and Pb-F) by graphite furnace atomic absorption after wet-ashing. Results Altogether, 467 women volunteered for blood sampling. Of these women, 375 also gave food duplicates. Geometric mean (GM) Cd-B levels in the 1990 study were lower than the corresponding 1980 values in most study sites so that the 1990 grand GM (1.98 ng/ml) for Cd-B was significantly lower than the 1980 CM (3.58 ng/ml). This reduction in Cd-B was related to the reduction in Cd-F (GM for Cd-F was 38.0 mu g/day in the 1980 study and 30.0 mu g/day in the 1990 study). Dietary intake was almost exclusively the route of Cd burden among the populations studied. Both Pb-B and Pb-F also showed a remarkable reduction, i.e. from 33.9 ng/ml (1980 GM) to 23.2 ng/ml (1990 GM) in the case of Pb-B, and from 32.2 mu g/day (1980 GM) to 7.1 mu g/day (1990 GM) in the case of Pb-F. Pb-B, however, did not correlate with Pb-F either in the 1980 or the 1990 study, because Pb intake via inhalation of air remained significant when compared with dietary intake. Conclusion The Cd burden in Japan has decreased markedly in the past 10 years, although it is still higher than in other countries. The Pb burden has been quite low.