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 β2-MG (microglobulin) ⩾1000 μg/gCr. Mortality risk analysis was performed using Cox’s proportional model to compare mortality between subjects with urinary β2-MG ⩾1000 and <1000 μg/gCr, and to investigate the relationship between the degree of urinary β2-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 β2-MG ⩾1000 μg/gCr. Significant increases in mortality risk for cerebral infarction in men and for malignant neoplasms in women with urinary β2-MG ⩾1000 μg/gCr were observed during the first five year observation period. For nephritis and nephrosis, the mortality risks for men and women with urinary β2-MG ⩾1000 μg/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 β2-MG in both sexes. Increased mortality risks for nephritis and nephrosis were identified in the subjects with urinary β2-MG ⩾10000 μg/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.
- Cd, cadmium
- ICD-9, International Classification of Diseases, Ninth Revision
- RBP, retinol binding protein
- SMR, standardised mortality ratio
- causes of death
- renal tubular dysfunction
- follow up study
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Published Online First 6 April 2006
Competing interests: none.
Ethics approval: The Ethics Committee of Kanazawa Medical University in Uchinada, Ishikawa 920-0293, Japan, where the analysis of the data was conducted, approved the study.