Health risk of heavy metals to inhabitants around mine contaminated areas via consumption of vegetables
ZOU Xiao-jin1,QIU Rong-liang1,2,,ZHOU Xiao-yong1,HUANG Sui-hong1(1. School of Environmental Science and Engineering,Sun Yat-sen University,Guangzhou 510275,China;2. Guangdong Provincial Key Lab of Environmental Pollution Control andRemediation Technology,Guangzhou 510275,China)
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 village 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:ShangbaXiabaSuoyikengHewu.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,indicating 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.