幼童誤食污染土壤後其胃部與腸道之重金屬生物可及性之評估

Evaluating the bioaccessibility of heavy metals in child’s gastrointestinal tract by soil inadvertently ingestion

劉儲芸(Chu Yun Liu)

指導教授 ： 許正一

國立屏東科技大學/工學院/環境工程與科學系所/碩士(2008年)

https://doi.org/10.6346/NPUST.2008.00108

摘要

誤食重金屬污染土壤為人體暴露危害途徑之一，且幼童常有手沾吮嘴的行為，而造成更高的危害風險。過去用來評估土壤重金屬生物有效性濃度的化學萃取法「生物有效性濃度」，並不適用在人體直接攝食污染土壤之條件下，而與動物試驗(in vivo)相比，體外試驗(in vitro)實驗時間短、成本低。本研究使用以生物學為基礎的體外萃取試驗(生理反應萃取法)來進行生物可及性(bioaccessibility)的評估，再以序列萃取法(sequential extraction)探討重金屬的化學型態與生物可及性濃度的關係，進而提供建立土壤中重金屬對於幼童的健康風險評估中暴露劑量的參考。實驗結果顯示Cd與Zn在胃腸道中之生物可及性，不論有無添加食物(牛奶與稀飯)皆與可交換態有顯著正相關（p＜0.01）。土壤pH值與Cu、Ni和Zn在胃部之生物可及性濃度有顯著正相關（p＜0.05），而有機質則與Cd有顯著負相關（p＜0.05）。陽離子交換容量與Pb有顯著負相關（p＜0.05）。另外，胃部（pH=1.5）重金屬之生物可及性大部分皆高於小腸道（pH=7.0）。整體而言，胃腸道之生物可及性濃度約為重金屬全量44 %左右。

關鍵字

體外試驗 ； 生物學為基礎的體外萃取試驗(生理反應萃取法) ； 生物可及性 ； 序列萃取法 ； 重金屬

並列摘要

Ingestion of contaminated soil has been recognized as an important exposure pathway of heavy metals for humans, especially for child through outdoor hand-to-mouth activities. Chemical extraction method has been used for evaluating the bioavailability of heavy metals in soils which was not suitable in the human body took in food directly condition of under the contaminated soil, moreover in vitro studies have the advantage of being rapid and relatively cheap in comparison with in vivo method. In addition the heavy metals characteristic and the gastrointestinal tract absorption condition, will all affect takes in the soil heavy metals solubility. Therefore in this study we use the physiologically based extraction test to assess the bioaccessibility of heavy metals of the study soils in child’s gastrointestinal tract. Sequential extraction procedure correlated the chemical forms of heavy metals and bioaccessibile concentrations, further provided the exposure dose reference in the soils regarding for assessment of child health risk. The results show that no matter whether food, the bioaccessibility of Cd and Zn in the gastrointestinal tract was significantly (p＜0.01）correlated with the exchangeable fraction. Soil pH was significantly (p＜0.05）positively correlated with the bioaccessibility of Cu, Ni and Zn in the gastric tract. Organic matter was significantly (p＜0.05）negatively correlated with the bioaccessibility of Cd. The bioaccessibility of Pb was significantly (p＜0.05）negatively correlated with cation exchange capacity. Most of the bioaccessibility of heavy metals in the gastric tract (pH 1.5) is higher than in the intestinal tract (pH 7.0), indicated that the gastrointestinal tract pH will affect the bioaccessibility of heavy metals. Therefore the results confirmed that exchangeable fraction, soil pH, organic matter and cation exchange capacity were important factors which controlled heavy metals bioaccessibility in the gastrointestinal tract.

並列關鍵字

in vitro ； physiologically-based extraction test(PBET) ； bioaccessibility ； sequential extraction ； heavy metal

參考文獻

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