Basta Nicholas T, Foster Jill N, Dayton E A, Rodriguez Robin R, Casteel Stan W
The School of Environment and Natural Resources, The Ohio State University, Columbus, Ohio 43210-1085, USA.
J Environ Sci Health A Tox Hazard Subst Environ Eng. 2007 Jul 15;42(9):1275-81. doi: 10.1080/10934520701434927.
In vitro gastrointestinal (IVG) methods have been developed to provide an expedient and inexpensive means to estimate bioavailability of arsenic and other contaminants from ingestion of contaminated soil. Both in vivo and in vitro techniques have used a fasting model when determining Pb bioavailability/bioaccessibility as a conservative estimate of risk. Some IVG procedures have incorporated a dosing vehicle (DV) or food (i.e., milk) to simulate in vivo conditions. Potential differences in the bioaccessibility of contaminants between fasting and fed states remain a concern for those interested in adopting in vitro procedures for regulatory purposes. In this study, the effect of eliminating a dough-like DV on As bioaccessibility (BA), and this effect on the relationship between in vitro bioaccessible and in vivo relative bioavailability (RBA) As is determined. Also, the effect of phosphate from the DV on IVG BA is investigated. Two types of smelter-contaminated soils, calcine and iron slag, were used to examine the effect of dosing vehicle (DV) on BA determined by IVG. Dosing vehicle did not affect BA in the gastric extraction (GE) or intestinal extraction (IE) for 3 of the 5 calcinated contaminated soils. Inclusion of DV in the GE slightly increased BA for 2 of the 5 slag-contaminated soils. Increases in BA from DV may be attributed to ligand exchange of arsenate with phosphate. Strong relationships between BA and in vivo RBA As were found with or without DV. Bioaccessible As measured by the GE was strongly correlated with in vivo RBA As (IVG without DV: r=0.92, P<0.01; IVG with DV: r=0.96; P<0.01). Similarly, BA measured by the IE was strongly correlated with in vivo RBA As (IVG without DV: r=0.90, P<0.01; IVG with DV: r=0.96, P<0.01). The IVG method, with or without DV, is a reliable method to use as a rapid screening tool to provide an estimate of BA in contaminated soils. Further studies should be conducted to determine the influence of foodstuffs on BA for different types of As contaminated soil (i.e., non-smelter soil).
体外胃肠道（IVG）方法已被开发出来，以提供一种便捷且廉价的手段来估算摄入受污染土壤中砷及其他污染物的生物利用度。在确定铅的生物利用度/生物可及性时，体内和体外技术均采用空腹模型作为风险的保守估计。一些IVG程序已纳入给药载体（DV）或食物（即牛奶）以模拟体内条件。对于那些有兴趣采用体外程序用于监管目的的人来说，空腹和进食状态下污染物生物可及性的潜在差异仍是一个关注点。在本研究中，确定了去除面团状DV对砷生物可及性（BA）的影响，以及这种影响对体外生物可及性与体内相对生物利用度（RBA）砷之间关系的影响。此外，还研究了来自DV的磷酸盐对IVG BA的影响。使用两种类型的冶炼厂污染土壤，即煅烧土和铁渣，来检验给药载体（DV）对IVG测定的BA的影响。对于5种煅烧污染土壤中的3种，给药载体在胃提取（GE）或肠提取（IE）中不影响BA。对于5种矿渣污染土壤中的2种，在GE中加入DV会使BA略有增加。DV导致的BA增加可能归因于砷酸盐与磷酸盐的配体交换。无论有无DV，均发现BA与体内RBA砷之间存在强相关性。GE测定的生物可及性砷与体内RBA砷密切相关（无DV的IVG：r = 0.92，P < 0.01；有DV的IVG：r = 0.96；P < 0.01）。同样，IE测定的BA与体内RBA砷密切相关（无DV的IVG：r = 0.90，P < 0.01；有DV的IVG：r = 0.96，P < 0.01）。无论有无DV，IVG方法都是一种可靠的方法，可作为快速筛选工具来估算污染土壤中的BA。应进一步开展研究，以确定食品对不同类型砷污染土壤（即非冶炼厂土壤）中BA的影响。
