Biological monitoring of the general population for cadmium.

Over 2000 blood samples and about 1000 24-h total food duplicates were collected in 49 non-polluted regions in Japan, and analysed for cadmium (Cd-B and Cd-F). Cd-B increased with age to reach a plateau at 40-59 years, where the geometric mean (GM) Cd-B was 3.2 ng/ml in men and 3.7 ng/ml in women. Smoking also increased Cd-B. The GMs of Cd-F were 43.9 and 37.0 micrograms/day for men and women, respectively, with boiled rice as a major source of cadmium (> 40%). Cd-B correlated significantly with Cd-F when compared on a regional mean basis. Similar Cd-B analyses among non-smoking women showed that Cd-B was lower in Korea (ca. 1.6 ng/ml) and in China (1.3 ng/ml) than in Japan. This observation is in accordance with the fact that rice in Korea (16.1 ng/g dry weight) and China (7.6 ng/g) contained less cadmium than that in Japan (52.5 ng/g). A preliminary follow-up in 1989 suggests a decrease in Cd-B (by ca. 30%) among the Japanese population, probably due to a reduction in cadmium in rice (ca. 14%) and a decreased rice intake.