Urinary β₂-microglobulin Concentration and Mortality in a Cadmium-polluted Area

A 9-y follow-up study of 3,178 persons who lived in a cadmium-polluted area was conducted to assess the influence of environmental cadmium exposure on long-term outcome. The standardized mortality ratios of the urinary beta 2-microglobulin-positive subjects (> 1,000 micrograms/g creatinine) of both sexes were higher than those of the general Japanese population, whereas the cumulative survival curves were lower than those of the urinary beta 2-microglobulin-negative group. A significant association was also found between urinary beta 2-microglobulin and mortality, using a Cox's proportional hazards model. Moreover, mortality rates increased in proportion to increases in the amount of urinary beta 2-microglobulin excreted. These results suggest that the prognosis for cadmium-exposed subjects with proximal tubular dysfunction is unfavorable. The mortality rate tended to become higher as the severity of renal dysfunction progressed.