A Retrospective Study on the Relation between Renal Dysfunction and Cadmium Concentration in Rice in Individual Hamlets in the Jinzu River Basin, Toyama Prefecture, Japan

Using as an index of exposure the Cd concentration in rice and as an index of health effect the urinary abnormality rate (proteinuria, glycosuria, and proteinuria with glycosuria) in the most systematic and extensive health screening examination conducted in 1967 and 1968 in the Jinzu River basin, Japan (a total of 13,183 subjects), we investigated whether a dose–response relationship exists between the two indices. For subjects that lived in the same hamlet since birth, with low Cd concentrations in rice it was confirmed that renal dysfunction does not develop unless the length of residence is prolonged, whereas with high Cd concentrations in rice renal dysfunction develops even when the length of residence is short. For subjects that lived in the same hamlet for over 30 years and that were aged over 50 years, the urinary abnormality rate in individual hamlets showed significant increases with increases in the mean Cd concentration in rice, demonstrating that a dose–response relationship existed. The allowable values of Cd concentration in rice were estimated to be in the range of 0.05–0.20 ppm, representing values lower than the 0.4 ppm provisionally adopted by the Japanese government