Urinary cadmium and mortality among inhabitants of a cadmium-polluted area in Japan

The influence of cadmium (Cd) body burden on mortality remains controversial. Excess mortality and the dose–response relationship between mortality and urinary cadmium excretion were investigated in this study among environmentally exposed subjects. A 15-year follow-up study was carried out on 3119 inhabitants (1403 men and 1716 women) of the Cd-polluted Kakehashi River basin, whose urinary Cd concentration was examined in a 1981–1982 health impact survey. The mortality risk of high urinary Cd (⩾10 μg/g Cr) subjects after adjustment for age using Cox's proportional hazard model was higher than that of moderate urinary Cd (<10 μg/g Cr) subjects in both sexes. When the subjects were divided into five groups according to the amount of urinary Cd (<3, 3–5, 5–10, 10–20, ⩾20 μg/g Cr), the mortality risk was significantly increased among the subjects with urinary Cd⩾3 μg/g Cr in proportion to the increases in the amount of urinary Cd concentration after adjustment for age, especially in women. Furthermore, special causes of death among high and moderate urinary Cd were investigated, and mortality risk ratio for heart failure, which is a cause of death often diagnosed in cases with a gradual deterioration culminating in death, was significantly increased in both sexes, compared with the moderate urinary Cd subjects. Also, in women the mortality risk for renal diseases in the high urinary Cd subjects was significantly higher than that in the moderate urinary Cd subjects. These results suggest that a causal association between Cd body burden and mortality exists among inhabitants environmentally exposed to Cd but that no special disease may be induced except renal diseases.