Epidemiology of renal tubular dysfunction in the inhabitants of a cadmium-polluted area in the Jinzu River basin in Toyama Prefecture.

Urinary beta 2-microglobulin (beta 2-m), alpha 1-microglobulin (alpha 1-m), amino-nitrogen, glucose, calcium, phosphorus, cadmium concentrations, and pH values were analyzed in urine samples from 187 females aged 55-66 years in the Jinzu River basin, which is known to be a cadmium-polluted area, and from 32 controls living in two adjacent reference areas in 1983-1984. Mean urinary beta 2-m, alpha 1-m, amino-nitrogen, glucose, cadmium concentrations and pH values in the inhabitants of the Jinzu River basin were significantly higher than those in the adjacent reference areas. Sixty-four inhabitants in a cadmium-polluted area were found to have renal tubular dysfunction with urinary beta 2-m level exceeding 1 mg/g creatinine and urinary glucose level exceeding 100 mg/g creatinine. The severity of renal tubular dysfunction in several inhabitants were comparable to those of the patients with Itai-itai disease. Mean cadmium concentrations in rice (mean: 0.32-0.57 ppm) which has been daily consumed by the inhabitants of the Jinzu River basin were significantly higher than those in the reference areas (mean: 0.12-0.13 ppm). The close relationship between cadmium exposure and the degree of renal tubular dysfunction was well demonstrated by principal component analysis.