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 GM (3.58 ng/ml). This reduction in Cd-B was related to the reduction in Cd-F (GM for Cd-F was 38.0 micrograms/day in the 1980 study and 30.0 micrograms/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 micrograms/day (1980 GM) to 7.1 micrograms/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.