Association between cadmium-induced renal dysfunction and mortality: further evidence.

Our previous follow-up study, carried out from 1979 to 1989, on 256 residents of Sasu, a cadmium (Cd)-polluted area located on Tsushima Island, Nagasaki Prefecture, Japan, showed a significant relationship between urinary beta 2-microglobulin (beta 2-m) excretion and mortality in men. To investigate the association between Cd-induced renal dysfunction and mortality more precisely, 275 residents in the same area aged 40-92 years, who had participated in a health survey conducted in May 1982, were followed to February 1989. The expected number of deaths was calculated on the basis of the sex- and 5-year-age-specific mortality rates for Tsushima Island in 1985. In both men and women with urinary beta 2-m concentrations greater than 1,000 micrograms/g creatinine, observed deaths were greater than the expected. However, the P value of the difference was less than 0.05 only in women. Analysis by the Cox proportional hazards model showed that, in both men and women, serum beta 2-m and creatinine, as well as urinary total protein and beta 2-m were significantly or marginally significantly related to mortality independent of age. In men, serum beta 2-m was more strongly related to mortality than urinary beta 2-m. The results provide further evidence for the causal association between Cd-induced renal dysfunction and mortality. The present report also discusses the role played by decreased glomerular filtration rate in the excess mortality of subjects with Cd-induced renal dysfunction.