Pu Xinzhu, Lee Linda S, Galinsky Raymond E, Carlson Gary P
School of Health Sciences, Purdue University, West Lafayette, Indiana 47907, USA.
Toxicol Sci. 2004 May;79(1):10-7. doi: 10.1093/toxsci/kfh091. Epub 2004 Feb 19.
The soil matrix can impact the bioavailability of soil-bound organic chemicals, and this impact is governed in part by soil properties such as organic carbon (OC) content, clay minerals, and pH. Recently, a physiologically based extraction test (PBET) was developed to predict the bioavailability of soil-bound organic chemicals. In the current study, the bioavailability of phenanthrene (PA) from laboratory-treated soils varying in OC content, clay, and pH was investigated using an in vivo rat model and an in vitro PBET. The relationship between these two approaches was also examined. In the in vivo assay, soils and corn oil containing equivalent levels of PA were administered to Sprague-Dawley rats by gavage at two dose levels: 400 and 800 mg/kg body weight. Equivalent doses were given via intravenous injection (i.v.). The areas under the blood concentration-versus-time curves (AUC) were measured, and the absolute and relative bioavailabilities of PA were determined for each soil. In the PBET tests, one g of each soil was extracted by artificial saliva, gastric juice, duodenum juice, and bile. The fraction of PA mobilized from each soil was quantified. The AUCs of PA in all soils were significantly lower than those following iv injection (p < 0.05), indicating that the soil matrix could reduce the bioavailability of PA from soil. There were obvious trends of soils with higher OC content and clay content, resulting in the lower bioavailability of PA from soil. A significant correlation (p < 0.05) was observed between the fraction of PA mobilized from soil in the PBET and its in vivo bioavailability. The data also showed that the absolute bioavailability of PA from corn oil was low: approximately 25%. These results suggest that PBET assay might be a useful alternative in predicting bioavailability of soil-bound organic chemicals. However, due to the limited soil types and use of one chemical vs. a variety of contaminants and soil properties in the environment, further efforts involving more chemicals and soil types are needed to validate this surrogate method.
土壤基质会影响土壤中有机化学物质的生物有效性，这种影响部分受土壤性质如有机碳（OC）含量、粘土矿物和pH值的控制。最近，一种基于生理学的提取试验（PBET）被开发出来以预测土壤中有机化学物质的生物有效性。在当前研究中，使用体内大鼠模型和体外PBET研究了来自不同OC含量、粘土和pH值的实验室处理土壤中菲（PA）的生物有效性。还研究了这两种方法之间的关系。在体内试验中，将含有等量PA的土壤和玉米油以两种剂量水平通过灌胃给予斯普拉格-道利大鼠：400和800毫克/千克体重。通过静脉注射（i.v.）给予等量剂量。测量血药浓度-时间曲线（AUC）下的面积，并确定每种土壤中PA的绝对和相对生物利用度。在PBET试验中，用人工唾液、胃液、十二指肠液和胆汁提取1克每种土壤。定量从每种土壤中释放出来的PA的比例。所有土壤中PA的AUC均显著低于静脉注射后的AUC（p<0.05），表明土壤基质可降低土壤中PA的生物有效性。存在OC含量和粘土含量较高的土壤具有明显趋势，导致土壤中PA的生物有效性较低。在PBET中从土壤中释放出来的PA比例与其体内生物有效性之间观察到显著相关性（p<0.05）。数据还表明，PA从玉米油中的绝对生物利用度较低：约为25%。这些结果表明，PBET试验可能是预测土壤中有机化学物质生物有效性的一种有用替代方法。然而，由于土壤类型有限以及使用一种化学物质与环境中多种污染物和土壤性质相对比，需要进一步开展涉及更多化学物质和土壤类型的工作来验证这种替代方法。
