Cadmium exposure of women in general populations in Japan during 1991-1997compared with 1977-1981

Objectives: The Japanese people are known to have high environmental exposu re to cadmium (Cd). The present survey was initiated to elucidate possible changes in the intensity of Cd exposure to the population by comparison of the present exposure level with the situation some 15 years ago. Methods: During 1991-1997, 24h food-duplicate samples, peripheral blood spe cimens and morning spot urine samples were collected from 588 non smoking w omen from 27 survey sites in sis regions, where food-duplicate and blood sa mples had also been obtained during 1977-1981 from 399 women. The samples w ere wet-ashed (after homogenization in the case of food-duplicates), and Cd in the wet-ashed samples was analyzed by inductively-coupled plasma mass s pectrometry for Cd intake via foods (Cd-F), Cd concentration in blood (Cd-B ) and Cd concentration in urine (Cd-U). The Cd-F and Cd-B were compared wit h the Cd-F and Cd-B obtained at the same sites in the 1977-1981 survey. Res ults: The exposure levels during 1991-1997 were such that Cd-F, Cd-B and Cd -Ucr (Cd-U after correction for creatinine concentration) were 25.5 mu g/da y, 1.90 mu g/1 and 4.39 mu g/g creatinine. Comparison with the 1977-1981 su rvey Results (i.e., 37.5 mu g/day for Cd-F and 3.37 mu g/l for Cd-B) showed that there were significant reductions (by 32 and 450%) in both parameters resp ectively during the last 15 years. The dietary route was an almost exclusiv e (i.e., 99% of the sum of dietary and respiratory uptake) route of Cd upta ke, of which Cd in rice (11.7 mu g/day) contributed about 40% of the total dietary intake. When compared among survey sites, inter-site variation in d ietary Cd intake was primarily due to differences in the intake through boi led rice. Despite the recent reduction in Cd exposure, the current exposure level for Japanese people is still higher than the levels among other rice -dependent populations in Asia as well as in other parts of the world. Comp arison was made between the present findings in general populations and obs ervations among known Cd-pollution cases in Japan. Conclusions: Dietary uptake is an almost exclusive route of Cd exposure in the general Japanese population. Boiled rice is a strong determinant of var iation in dietary Cd intake. Whereas there was a substantial reduction in C d exposure among Japanese populations in the last 15 years, the current lev el is still high when compared internationally.