Studies on renal tubular function in formerly cadmium-exposed residents after the restoration of environmental cadmium pollution

本文于1979年5月25日至26日和1987年6月26日至27日对日本长崎县对马岛伊豆原镇Kashine区镉污染区居民进行了流行病学调查。该地区被指定为镉污染地区，因为未经抛光的家庭大米中镉的浓度低于1.0 ppm。要求6岁以上的人参加1979年的健康检查。1979年前后，居民通过食物摄入镉的平均量为250 < micmicr> g/天。喀什地区镉污染稻田登记工作始于1980年，1984年完成。此后，居民通过食物摄入镉的平均量急剧下降到70 < micr> g/d，几乎等于日本人的平均日镉摄入量。有61人在1979年和1987年两次参加了健康检查。研究人员收集了参与者清晨的尿液样本。用放射免疫法和偏振塞曼无焰原子吸收分光光度法分别测定尿中β -2微球蛋白和镉。1979年尿β -2微球蛋白和镉含量高的人在1987年尿β -2微球蛋白和镉含量也高。即居民肾小管功能不全。另一方面，1979年显示上述两种水平正常的人显示出这些水平正常。由此可见，镉摄入量从250 ~ 70 <micrn>g/d降低4年对已建立的肾小管功能障碍无影响。

The epidemiologic study was carried out on 25-26, May, 1979 and on 26-27, June, 1987 on residents living in cadmium-polluted area, Kashine district located in Izuhara town, Tsushima Island, Nagasaki Prefecture, Japan. The district was designated as a cadmium-polluted area when cadmium concentrations in unpolished household rice were observed to be avobe 1.0 ppm.People older than 6 years were requested to participate in 1979's health examination. Residents' average intake of cadmium via foods around 1979 was 250 <micrn>g/day. The restration of cadmium-polluted paddy fields in Kashine district was started in 1980 and completed in 1984. After then residents'average intake of cadmium via foods sharply decreased to 70 <micrn>g/day almost equal to average Japanese daily intake of cadmium.61 people participated in both health examinations in 1979 and 1987. Early morning urine samples were collected from participants. Urinary beta-2-microglobulin and cadmium were determined by a radioimmunoassay and polarized Zeeman flameless atomic absorption spectrophotometry, respectivley.People showing high levels of urinary beta-2-microglobulin and cadmium in 1979 showed also high levels of both urinary beta-2-microglobulin and cadmium in 1987. Namely residents'renal tubular dysfunction remained unchanged. On the other hand, people showing normal levels of both mentioned above in 1979 showed normal levels of those.It was concluded that decrease of cadmium intake of 4 years from 250 to 70 <micrn>g/day had no effect on established renal tubular dysfunction.