广州市不同功能区土壤铅的健康风险评估

Health Risk Assessment of Lead in Soils in Different Functional Areas of Guangzhou

[目的]了解广州市不同功能区土壤铅(Pb)污染状况及其生物可给性,初步探讨Pb生物可给量的影响因素,评估不同功能区土壤Pb经口无意摄入途径的人体健康风险。[方法]选择广州居民区、商业区、汽车站、文教区、医疗区和公园土壤为研究对象,采用体外实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含量并计算其生物可给性,根据Pb生物可给量进行健康风险评价。[结果]广州市中小城区土壤Pb平均含量(90.34mg/kg)高于广州市、广东省和中国土壤背景值(P<0.05)。土壤在模拟胃、小肠阶段中Pb平均生物可给性分别为36.55%、9.03%,其中以公园最高(41.98%,14.17%)。儿童和成人经口无意摄入途径的Pb平均摄入量分别为18.32、4.58μg/d,其中商业区最高(28.14、7.03μg/d)。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6.86、1.46μg/d,其中以商业区最高(13.03、2.03μg/d);成人在模拟胃阶段和小肠阶段中的Pb平均生物可给量则分别为1.72、0.36μg/d,其中商业区最高(3.26、0.51μg/d)。儿童和成人在胃肠消化阶段中Pb生物可给量与土壤Pb总量有直线关系(P<0.05)。不同功能区土壤Pb对儿童和成人的健康绝对风险系数(Ka)以及模拟胃、小肠阶段的健康相对风险系数(Kr1、Kr2),均未超过世界卫生组织(WHO)人体健康风险警戒线。[结论]广州市不同功能区土壤Pb污染程度不同,但不同功能区土壤Pb尚未超过WHO人体健康风险警戒线。

[ Objective] To explore the bioaccessibility of Pb in soil and its influencing factors in different functional areas of Guangzhou, and to assess the health risk of hand-to-mouth exposure to Pb. [ Methods ] Triplicate soil samples were collected separately from 9 commercial districts, 9 bus stations, 9 residential areas, 6 education areas, 6 hospitals, and 7. parks in Guangzhou city as the research object. An in vitro digestion model was developed to assess bioaccessibility and health risks. Soluble Pb contents in simulated stomach and intestinal solutions, as well as Pb contents in soil, were determined using atomic absorption spectrometry. [ Results ] The mean content of Pb in soils of different functional areas （90.34mg/kg） exceeded the Pb background values in soils of Guangzhou, Guangdong, and China, respectively （P 〈 0.05）. The average bioaecessibility of Pb in the simulated stomach and intestinal phases were 36.55% and 9.03% respectively, in which the park soil presented the highest values （41.98%, 14.17%）. The average intakes of Pb by oral exposure among children and adults were 18.32 μg/d and 4.58μg/d, respectively, in which the commercial district soil was the highest （28.14 μg/d, 7.03 μg/d）. The average bioaecessible amounts of Pb for children in simulated gastric and intestinal phases were 6.86 μg/d and 1.46 μg/d, with the highest values in the commercial district （13.03 μg/d, 2.03 μg/d）; and those for adults were 1.72 μg/d and 0.36 μg/d, respectively, also with the highest values in the commercial district （3.26 μtg/d, 0.51 μg/d）. There were good linear relationships between bioaccessible values and total Pb content in soil （P 〈 0.05）. The values of absolute health risk coefficient （Ks） and the relative risk coefficients for simulated gastric phase （Kr1） and simulated intestinal phase （Kr2） in different functional areas were within the permitted maximum Pb intake levels for both children and adults as suggested by the World Health Organization （WHO）. [ Conclusion ] Soil Pb contamination levels vary in different functional areas in Guangzhou, but not exceed the WHO human health risk warning line.