Izuno T, Sugita M, Arita S, Otahara Y, Nasu I, Tsuchiya K, Hayashi Y
Department of Environmental and Occupational Health, Toho University School of Medicine, Tokyo 143-8540, Japan.
Environ Res. 2000 Nov;84(3):275-81. doi: 10.1006/enrs.2000.4093.
It is well known that cadmium (Cd) causes renal dysfunction such as increase of beta(2)-microglobulin excretion into urine. Although Cd in rice seems to be one of the largest sources of total Cd intake in Japan, there are very few studies that have epidemiologically clarified the relationship between Cd concentration in rice (Cd-R) and renal dysfunction, because such studies are basically ecological studies, in which confounding factors are difficult to take into consideration. To derive safety levels for foodstuff from Cd-R, it is essential to evaluate the effect of confounding factors. Thus, we investigated the dose-response relationship between renal dysfunction and not only Cd-R but also confounding factors, and we tried to determine whether Cd-R is an adequate indicator of "dose" in the dose-response relationship between Cd intake and renal dysfunction. In 1971, Cd-R data were obtained from rice samples collected by the Environment Agency, Government of Japan in the Fuchu area of Toyama Prefecture, which is known as a place where many itai-itai disease patients were found, and medical data were collected during 1979-1984 by Toyama Prefecture. First, the dose-response relationship between Cd-R and renal dysfunction was analyzed using the data from the Fuchu area. Second, to investigate the effect of confounding factors, analysis using the data from both the Fuchu area and an unpolluted area with environmental factors different from those of the Fuchu area was performed. The results showed that the cause of renal dysfunction could not be explained by Cd-R alone, and confounding factors were not negligible. Although it is difficult to clarify precisely the confounding factors from the available data, it is concluded that deriving a safety level for foodstuffs using only the Cd-R level as a reference is not appropriate.
众所周知，镉（Cd）会导致肾功能障碍，如尿中β2-微球蛋白排泄增加。虽然大米中的镉似乎是日本镉总摄入量的最大来源之一，但从流行病学角度阐明大米镉浓度（Cd-R）与肾功能障碍之间关系的研究非常少，因为此类研究基本上属于生态学研究，难以考虑混杂因素。为了从Cd-R得出食品的安全水平，评估混杂因素的影响至关重要。因此，我们研究了肾功能障碍与Cd-R以及混杂因素之间的剂量反应关系，并试图确定Cd-R是否是镉摄入量与肾功能障碍之间剂量反应关系中“剂量”的合适指标。1971年，Cd-R数据来自日本政府环境省在富山县府中地区采集的大米样本，该地区是发现许多痛痛病患者的地方，医疗数据由富山县在1979年至1984年期间收集。首先，使用府中地区的数据分析Cd-R与肾功能障碍之间的剂量反应关系。其次，为了研究混杂因素的影响，使用府中地区和一个环境因素与府中地区不同的未受污染地区的数据进行分析。结果表明，肾功能障碍的原因不能仅用Cd-R来解释，混杂因素不可忽视。虽然从现有数据中难以精确阐明混杂因素，但得出的结论是，仅以Cd-R水平作为参考来推导食品的安全水平是不合适的。
