More than fifteen years has been passed since the restoration of paddy fields in Cd polluted Kakchashi River basin, Japan. To investigate the influence of environmental cadmium: exposure on mortality after improvement of pollution, changes of mortality and causes of deaths were investigated among the subjects with increase of urinary â2-microglobulin(MG) excretion.
A 15–year follow-up study was carried out on the 3119 inhabitants (1403 men and 1716 women) aged >= 50 years old living in the cadmium polluted Kakehashi River basin, whose urinary excretion of β2-MG was examined in a 1981–2 health impact survey. The observation period was divided into three 5-year periods, 1981–1986, 1987–1991, 1992–1996, and the standardized mortality ratios (SMR) for all and special causes of death of the subjects with urinary β2-MG >= 1000μg/gCr or < 1000μg/gCr were compared with those of the Japanese general population in each observation period.
Excess mortality among the subjects with urinaryβ2-MG (> = 1000μg/gCr) was observed in both sexes in all periods. The SMR for all causes were higher in the women in all observation periods. The diseases contributing most to these increase of mortality were heart failure and cerebrovascular diseases. In women the SMR for heart failure was significantly increased in all periods. The SMR for cerebrovascular infarction was significantly higher in the men after 1987. In 1987–1991 the SMR for digestive diseases was higher in the women. In both sexes, the SMR for renal diseases was higher in 1992–1996, when 5–10 years had passed since the restoration was completed.
The prognosis of the inhabitants with the increase of urinary β2-MG induced by Cd is unfavorable, with higher mortality rates due to heart failure, cerebrovascular diseases.
(1) Department of Public Health, Kanazawa Medical University
(2) School of Health Sciences, Faculty of Medicine, Kanazawa University
(3) Department of Hygiene, Faculty of Medicine, Chiba University
(4) Division of Health and Welfare, Ishikawa Prefecture