In vitro系统评价胃肠液pH及土液比对铅、镉、砷生物可给性的影响

土壤中铅、镉、砷可能直接通过人的口部无意摄入进入人体,危害人体健康,而各研究者评价土壤重金属对人体健康风险所用的实验参数有别,结果缺乏可比性,因此探讨不同评价方法对结果的影响具有重要意义。以污染的棕钙土和红壤为研究对象,应用in vitro方法研究分析胃肠阶段不同土液比、pH以及土壤性质对铅、镉、砷生物可给性的影响。结果表明,重金属的生物可给性与in vitro系统中的pH、土液比、土壤类型以及重金属本身有关。在胃阶段,随着土液比升高,3种重金属生物可给性趋于降低;不同土液比处理下,红壤中铅生物可给性大于棕钙土,而砷则相反,红壤和棕钙土中镉的生物可给性差异不明显。在肠阶段,随着土液比升高,3种重金属生物可给性也趋于降低（除了红壤镉以外）,土液比1∶100的3种重金属生物可给性均显著大于1∶10。不同pH处理下,铅的生物可给性随pH的升高逐渐降低,而pH对镉和砷的生物可给性的影响与土液比有关。因此,肠胃实际吸收的重金属可能与摄入水量、食物成分与组成以及食物摄入引起的肠液pH变化有关。

In vitro Model System to Evaluate the Influence of pH and Soil-gastric/intestinal Juices Ratio on Bioaccessibility of Pb, Cd and As in Two Typical Contaminated Soils

Bioaccessibility is one of important evaluating methods for the risk of poisonous soil particles to human. And the meihod of in vitro digestion has been used to access the bioaccessibility of heavy metals in dust from contaminated soils, such as lead（Pb ）, cadmium（ Cd ） and arsenic （As）. In order to figure out the influence of different soil-to-solution ratio and pH on the bioaeeessibility of heavy metals （%） in stomach and intestine, two typical contaminated soils were estimated using the method of in vitro digestion. The current results demonstrated that the differences in bioaccessibility of heavy metals were determined as a function of the pH, soil to solution ratios, soil types, digestive or- gans, and metal oneself. In stomach, the bioaccessibility of Pb, Cd, As in two soils tended to decrease with increasing soil to gastric juice ratio; the bioaceessibility of Pb in red soil was greater than that in brown calcic soil, but the opposite conclusion for As, while no significant differ- ences for Cd. In intestine, the bioaccessibility of Pb, Cd, As in two soils also tended to decrease with increasing soil to intestinal juice ratio un- der three tested pH except for Cd in red soil. The bioaccessibility of Pb in two soils decreased with pH from 6 to 8, while the influences of in- testinal juice pH on bioaccessibility of Cd, As were determined as a function of soil to intestinal juice ratios. Therefore, the actual uptake of heavy metals in stomach/intestine could depend on drinking water, and food composition and structure given food-induced pH change in gas- tric/intestinal juices.