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Exposure to cadmium and lead was studied using a dietary survey. Data for 1348 individuals aged 25-64 years were collected using 3-day food records. In addition to the dietary intake of heavy metals, the effect of the following were also analyzed: smoking frequency, place of residence, occupation and age. Total cadmium and lead exposure was estimated by calculating intake from food plus that from inhalation, i.e. from urban air and smoking. Heavy smoking increased the cadmium exposure three-fold. The distribution curve of total cadmium exposure was bimodal due to the additional exposure caused by smoking. The distribution curve of the lead and cadmium exposure from food was also skewed, being mostly influenced by food intake. Contaminated urban air slightly increased the total exposure to lead. Occupation had a minor effect on the exposure to both metals. Housewives and retired persons were the least exposed groups. The distribution pattern and wide range of heavy metal exposure should be taken into account in risk assessment for contaminants in food. The additional exposure to cadmium and lead from smoking and from air and water should be considered.

The study of health problems due to cadmium pollution in Japan originated from an endemic episode of Itai-itai disease in a rural area in north-central Japan after World War II. The disease was defined as osteomalacia with tubular changes in the kidney and considered to be associated with excess intake of cadmium. This episode motivated the Japanese Government to conduct health examinations on the general population in cadmium-polluted and non-polluted areas throughout the country since 1969. Although Itai-itai disease-like bone changes were rarely found, these studies revealed a higher prevalence of renal tubular dysfunction among elderly people in the cadmium-polluted areas. No significant difference was noted in cancer mortality, but mortality from cardiovascular diseases and all causes tended to be lower in cadmium-polluted areas. Clinical and pathological studies in man as well as experiments on primates have recently been made to elucidate the pathogenesis of Itai-itai disease and the health effects of cadmium. The lack of knowledge on the ecological and biological complex of cadmium resulted in the impediment of studies on this problem. The lesson from this experience is that basic research is essential for promoting the study of pollutants such as heavy metals, though pollution problems usually require urgent solutions.

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.