Causes of death and renal tubular dysfunction in residents exposed to cadmium in the environment.

OBJECTIVES

To clarify the causes of death of residents with renal tubular dysfunction induced by cadmium (Cd) in the environment.

METHODS

A 15 year follow up study was performed with the inhabitants living in the Cd polluted Kakehashi River basin in Japan. Standardised mortality ratios (SMRs) for causes of death, classified by ICD-9, were computed using the person-years method to investigate the excess mortality of subjects with urinary beta2-MG (microglobulin) > or =1000 microg/gCr. Mortality risk analysis was performed using Cox's proportional model to compare mortality between subjects with urinary beta2-MG > or =1000 and <1000 microg/gCr, and to investigate the relationship between the degree of urinary beta2-MG and mortality.

RESULTS

Excess mortality due to heart failure and cerebral infarction in both sexes, and nephritis and nephrosis in men, was observed among subjects with urinary beta2-MG > or =1000 microg/gCr. Significant increases in mortality risk for cerebral infarction in men and for malignant neoplasms in women with urinary beta2-MG > or =1000 microg/gCr were observed during the first five year observation period. For nephritis and nephrosis, the mortality risks for men and women with urinary beta2-MG > or =1000 microg/gCr significantly increased over the 15 year observation period. The mortality risks for heart failure and cerebral infarction increased in proportion to the increased urinary beta2-MG in both sexes. Increased mortality risks for nephritis and nephrosis were identified in the subjects with urinary beta2-MG > or =10000 microg/gCr in both sexes.

CONCLUSION

Renal tubular dysfunction induced by Cd affected the causes of death, and mortality for heart failure, cerebral infarction, and nephritis and nephrosis was increased among inhabitants living in a Cd polluted area in Japan. In women, cancer mortality may have been increased while Cd pollution was ongoing.