基于体外模拟法的城市土壤铅的健康风险评估

Health Risk Assessment of Lead in Urban Soil by Simulation Methods in vitro

目的了解广州主城区土壤的Pb生物可给性,探讨土壤Pb生物可给性的影响因素,评估广州主城区土壤Pb经口无意摄入的人体健康风险。方法选择广州主城区62个采样点的土壤为研究对象,采用体外试验法模拟人体消化系统进行消化,运用原子吸收分光光谱法测定胃、小肠消化阶段反应液中可溶态Pb和土壤Pb含量。结果广州主城区土壤Pb平均含量高于广州市、广东省和中国土壤背景值(P<0.05);广州主城区土壤在模拟胃阶段Pb平均生物可给性(33%)高于小肠阶段(7.0%);不同城区儿童、成人经口无意摄入途径的Pb平均摄入量分别为28.51、7.13μg/d,不同城区儿童、成人Pb摄入量的分布差异存在统计学意义(P<0.05),其中黄埔区儿童、成人Pb摄入量最高(129.92、32.48μg/d);不同城区的儿童在模拟胃阶段和小肠阶段中的Pb平均生物可给量分别为11.58、1.85μg/d,成人则分别为2.89、0.46μg/d,不同城区儿童、成人在模拟小肠阶段中Pb生物可给量的分布差异有统计学意义(P<0.05);胃肠消化阶段中Pb溶出量与土壤Pb总量呈正相关(P<0.05);黄埔区土壤Pb的儿童健康绝对风险系数(Ka=2.4)、模拟胃阶段健康相对风险系数(Kr1=1.38)超过WHO人体健康防线警戒线。结论广州主城区土壤Pb不同程度受到污染,黄埔区土壤铅对儿童的健康风险应引起重视。

Objective To explore the bioavailability of lead and its influencing factors in soil in the main area of Guangzhou, and assess the health risk of soil-oral exposure of lead by in vitro simulation methods. Methods The soil samples were collected from the main area of Guangzhou by the method of lattice technique. The soil samples were digested by in vitro method and the soluble content of lead in the solution in the simulated stomach phase and intestinal phase were determined respectively and total lead in soil was determined with AAS. Results The mean content of lead in the main area of Guangzhou exceeded the background value in soils in Guangzhou, Guangdong and China respectively （P〈0.05）. The average bioavailability of lead in the stomach phases was higher than that in intestinal phases. There was significant difference among different district in the intakes of lead for children and adults, respectively （P〈0.05）.The average intakes of lead by soil-oral exposure for children and adults in different district were 28.5μg/d, 32.48 μg/d, respectively in which the Whampoa district was the highest （129.92μg/d, 7.03 μg/d）. The average amounts of available lead for children in simulated gastric and intestinal phases were 11.58 μg/d, 1.85 μg/d in different district, which for adult were 2.89 μg/d, 0.46 μg/d, respectively. There was a significant difference among different district in the amounts of available lead for children and adults, respectively （P〈0.05）. There were good linear relationships between bioavailability values and total metal concentrations （P〈0.05）.The values of the absolute health risk coefficient （Kn）, simulated gastrointestinal phase of health relative risk coefficient （Kn） in the Whampoa district, which were higher than the tolerant lead intake level for child and adult in soil, suggested by WHO. Conclusion The soil in the main area of Guangzhou is polluted by lead in varying degree. The values of the Ko and Kn in the Whampoa district for child are higher than the human heahh risk warning line presented by WHO.