わが国における土壌中重金属類の暴露量推定 地圏環境評価システムの開発に関する研究

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We have developed the geo-environmental risk assessment model for heavy metals, which are considered both soil properties and exposure factors specific to Japanese situations. The exposure rates, the distribution of exposure paths and the risk level of soil content to the human have been evaluated by using this model.Since the Japanese soil have the specific properties, i.e. high pH, high fraction of organic carbon content and high fraction of clay content, it is difficult to transport into the groundwater and the crops in comparison with other kinds of soil. The exposure rates of children are higher than those of adults. Especially, infants aged 1 to 2 are much exposed to the heavy metals. The major exposure paths of the human are different due to the kind of heavy metal. The human are mainly exposed to lead and chromium from direct ingestion of soil, whereas they are mainly exposed to selenium and cupper from intake of drinking water. The soil contents of exposure limit are estimated at 37 mg / kg for arsenic, 26 mg / kg for cadmium, 620 mg / kg for chromium, 4,600 mg / kg for cupper, 4.0 mg / kg for mercury, 120 mg / kg for lead and 1.6 mg / kg for selenium.