また平成14年度には、牛乳摂取にともなう人間へのSb曝露に関して最も重要な基礎資料となるSbの牧草への経根吸収特性をポット実験により把握した。その結果、ほとんど全ての牧草試料でSbが検出されることから、Sbは牧草に経根吸収されること、葉中Sb濃度が茎中Sb濃度を上回り、Sbは茎よりも葉に濃縮されることがわかった。土壌中Sb濃度が極端に高くなると牧草中Sb濃度は明らかに増加する。その場合、牧草の収穫を重ねても牧草中Sb濃度に変化がほとんどみられないことから、牧草が吸収できるSbの量には上限がある可能性が示唆された。
The objectives of this study are to determine toxic elements as air deposition in environment samples around an incinerator surrounded with grass field through field survey, and to examine some aspects of health risk with experiments. Soils, plants and particle matter in air were collected at several points around it. Concentrations of trace elements were measured by means of Instrumental Neutron Activation Analysis.
Antimony (Sb) concentrations in surface soils decrease monotonously in near area of the incinerator within 300m distance. Vertical soil profile in vicinity of it denotes that Sb in excess of natural background value of 1mg/kg remaining within 12cm depth, has been successively accumulated in surface. Sb in grass samples also decrease with distance from the incinerator and washing with water is able to make them clean. These facts imply that antimony is considered as chemical fallout exhausted form the incinerator.
It is significantly important that Sb is one of toxic substances released from incinerators beside dioxins. To properly evaluate the potential health risks of Sb near it, Sb concentrations in environment, and Japanese organs and tissues were collected from previous works. The data is not sufficient to estimate antimony exposure through both dietary and inhalation intake. Concerning with the physiologically based pharmacokinetic model (PBPK model) of lead, the PBPK model of antimony exposure to reference Japanese is constructed, taking critical organs and critical excretion pathways into account. Further activities are necessary for estimating parameter values in it, and improving it more precisely.
Some basic experiments on Sb absorption of grass through root were performed. Detecting Sb in almost samples denote that they absorb Sb. Stem concentrations were smaller than leaf ones, indicating Sb is accumulated in leaf. Sb in grass is getting bigger with increasing Sb in soil, consequently having the upper limit of Sb in grass.
その他のタイトル
Determination of Toxic Elements as Chemical Fallout in Environment Samples around an Incinerator Surrounded with Grassland, and Evaluation of Related Health Risk
清掃工場周辺の酪農地域における有害元素降下物の同定とそのリスク評価
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