中国典型土壤中铅的生物可给性的影响因素分析与健康风险评估

土壤铅污染及其危害备受关注。作为评估其对人体健康风险的科学指标之一,土壤铅的生物可给性的影响因素仍不甚明确。采集中国5种典型土壤(红壤、褐土、黑土、棕壤和黄壤),根据国标中一类建设用地的管制值制备成800 mg·kg^-1的铅污染土壤样品,利用先进的基于生理学的体外试验方法(改进的PBET模型)研究经口部摄入的土壤铅的生物可给性及其对人体的健康风险,进而从土壤理化性质和铅的赋存形态角度,全面综合地探讨土壤铅的生物可给性的影响因素,并分析不同土壤间差异的原因。结果表明,土壤铅在胃阶段的生物可给性为72.7%—82.6%,各类型土壤间差异极显著,其中红壤较高而黑土较低;进入小肠阶段后,土壤铅的生物可给性极显著降低至22.8%—27.7%,各类型土壤间无显著差异。土壤铅对人体的健康风险评估结果与之相同。对儿童而言,土壤铅在胃阶段的非致癌风险达到可接受限值的2.1倍;且整体而言,土壤铅对儿童的非致癌风险平均达到成人的7.6倍,必须加以重视。此外,土壤铅的生物可给性与土壤pH、有机质质量分数和迁移系数均存在高度显著相关性,其中,土壤pH是影响土壤铅在胃肠道的生物可给性的主导因子。通过体外试验可直接、简便而准确地获取土壤铅的生物可给性信息,建议在今后实地的污染土壤健康风险评估工作中引入该方法。该研究成果将为铅污染土壤健康风险评估工作提供准确的科学依据与有价值的参考。

Study on the Influencing Factors of Pb Bioaccessibility in Typical Soils in China and the Human Health Risk Assessment

Soil Pb contamination and its harmful effects draw wide concern.Bioaccessibility provides a scientifically sound way to assess the health risk of soil Pb,however,the influencing factors remain uncertain.In this study,five typical soils(i.e.,red soil,cinnamon soil,black soil,brown soil and yellow soil)in China were artificially contaminated with Pb to a concentration of 800 mg·kg^?1,according to the risk intervention value for type 1 development land in the national standard.The bioaccessibility of soil Pb through oral ingestion was then studied using advanced physiologically-based in vitro test(modified PBET model),and the relevant health risk was assessed.Besides,the influencing factors of Pb bioaccessibility were comprehensively investigated from the aspects of soil physicochemical properties and fractionation of soil Pb,and accordingly the difference between soils was discussed.Results showed that the bioaccessibility of soil Pb ranged from 72.7%to 82.6%in gastric phase,with significant difference between soils,and red soil showed relatively higher Pb bioaccessibility while black soil showed relatively lower Pb bioaccessibility.After entering small intestine phase,the bioaccessibility of soil Pb significantly declined to 22.8%–27.7%,with non-significant difference between soils.The human health risk assessment obtained the same qualitative results.It should be noted that for children the non-carcinogenic risk of soil Pb in the gastric phase was 2.1 times the acceptable limit,and the overall non-carcinogenic risk of soil Pb for children was on average 7.6 times that for adults.In addition,significant correlation was respectively found between the bioaccessibility of soil Pb and soil pH,organic matter content,and migration factor,and soil pH was determined to be the dominant factor.In vitro test helps to obtain the information of the bioaccessibility of soil Pb in a direct,convenient and accurate manner,and is hence recommended to the field survey on the health risk of real contaminated soils.This study provides accurate scientific basis and valuable reference for the health risk assessment of Pb-contaminated soils.