蔬菜重金属暴露接触对大宝山矿区及周边居民的健康风险

Health risk of heavy metals to inhabitants around mine contaminated areas via consumption of vegetables

通过36个土壤样品,32个灌溉水及120个蔬菜样品的调查研究,结果表明,广东韶关翁源县大宝山及周边的四个地区土壤、灌溉水及蔬菜中重金属含量都表现为:上坝>下坝>蓑衣坑>何屋。下坝、蓑衣坑及何屋通过食用蔬菜日均Pb、Zn、Cd、Cu摄入量均未超过FAO/WHO人均日摄入可允许限量标准。但上坝居民通过蔬菜摄入Pb和Cd的DI分别为PTDI的1.40和1.35倍。靶标危害系数(Target hazard quotients)THQ研究结果表明,何屋和蓑衣坑的蔬菜中几种重金属的THQ值均小于1,说明蔬菜途径摄入重金属对其居民健康风险很低。上坝居民通过蔬菜摄入的Pb和Cd的THQ均大于1,蔬菜途径重金属暴露接触对上坝居民健康具有潜在风险。居住在污染河流横石河下游的上坝居民面临严重的重金属接触暴露风险,显著高于对太平河上游及下游居民的健康风险。

Vegetables have been reported as an important route of human exposure to heavy metals. This study aims to evaluate the health risks associated with ingesting heavy metals through vegetables for the general population of four districts （Shangba, Xiaba, Suoyikeng and Hewu） which were contaminated by mine exploiting and acid mine drainage irrigating in Dabao Mountain, Guangdong province, China. Soil samples （36）, irrigative water （32） and vegetable samples （120） were collected from the 4 districts and heavy metals analyzed by atomic absorption spectrometry （AAS）. The mean concentrations of Pb, Zn, Cd and Cu of the soils in Shangba village were 843.7, 2112.0, 2. 66 and 586.3 mg/kg, respectively, and were 3.8, 10.6, 8. 9 and 11.7 times compared to the tolerant limit level in China. The vegetable concentrations in Shangba vil- lage were 4.0, 1.1 and 5.6 times of the tolerant limit level of vegetables in China. While the mean concentrations of Pb and Cd in the other three districts were also higher than the tolerant limit level of vegetables in China. The heavy metal concentrations of soil and irrigation water and vegetables in the 4 districts were in the order： Shangba〉Xiaba〉Suoyikeng〉Hewu. The average daily intakes （DI） of Pb and Cd in Shangba were 0.28 and 0. 097 mg/d, which were 1.40 and 1.35 times of the provisional tolerable daily intake （PTDI） established by FAO/ WHO. While the Dis of Zn and Cu in Shangba were below the PTDI. The Dis of heavy metals in the other three districts were also below the PTDI. The target hazard quotients （THQs） can be used to evaluate the health risks with heavy metals by vegetable concentrations consumed in inhabitants. The THQ of heavy metals of vegetables in Hewu and Suoyikeng were below 1, while the Pb and Cd in Shangba were more than 1, indica- ting,that Pb and Cd were the key heavy metals which affected health risk of the inhabitants in this polluted area. It also showed that the inhabitants who lived near the contaminated river faced the adverse health risk. It indicated that health risk was caused mainly by AMD irrigating. Shangba villagers had higher health risk because they irrigated heavily contaminated water from Hengshi river, while Hewu villagers had less health risk by using contaminated water for irrigation. The THQ of Cd of Shangba village through vegetables was similar to that of Taiwan through oyster, while the THQ of Zn and Cu were lower than that. The THQ of heavy metals in Hewu was similar to those of uncontaminated areas.