万山汞矿区居民食用大米的汞暴露风险评估

Mercury exposure and its health assessment for the residents in Wanshan mercury-mining areas via the rice consumption

为明确汞矿区大米汞污染对人体的暴露风险,分别运用冷原子荧光技术（CVAFS）和气相色谱冷原子荧光技术（GC-CVAFS）对贵州万山汞矿区大米中总汞（THg）和甲基汞（Me Hg）质量比进行了测定,并借鉴粮农组织/世界卫生组织食品添加剂联合专家委员会（JECFA）和美国国家环保局（USEPA）的计算模型和研究成果,在区域层面上重点探究了汞矿区居民因食用大米而存在的THg和Me Hg暴露风险。结果表明,大米中THg和Me Hg质量比分别为2.83~295.53 ng/g和2.3~43.18 ng/g;居民THg日摄入量和JECFA安全标准下的健康风险指数（HRI）范围为0.02~1.77μg/（kg·d）和0.03~2.49;居民Me Hg日摄入量范围为0.01~0.26μg/（kg·d）,JECFA和USEPA安全标准下的HRI范围分别为0.04~1.13和0.1~2.6;模型计算出的人体头发Me Hg质量比范围为0.17~3.11μg/g,分别有5%和38.33%的监测点超出JECFA和USEPA规定的人体发汞的安全限值。大米THg、Me Hg质量比和人体接受大米THg、Me Hg的健康风险均随远离矿坑不同程度地降低。食用大米已经成为矿区居民汞暴露的重要途径,产生的暴露程度与水稻种植位置关系密切,但这种风险目前整体还处于可控范围,需要及时采取相应措施避免风险扩大。

The paper wishes to present its research report on the investigation and testing of the concentrations of the total mercury（THg） and methylmercury（MeH g） pollution in the rice produced in Wanshan Hg-mining areas in Guizhou by using the CVAFS and GC-CVAFS methods.Based on the estimating models from Joint Expert Committee on Food Additives（JECFA） and United States Environmental Protection Agency（US EPA）,we have investigated and made an assessment of the risks of THg and MeH g exposure brought about to rice consumers in the mercurymining area.As a result of our measurement,the mass ratios of THg and MeH g in the said rice for consumption have been found ranging from 2.83 ng/g to 295.53 ng/g and 2.3 ng/g to 43.18 ng/g,respectively.The daily intake of THg and MeH g by the rice consumers ranges from 0.02 μg/（kg · d） to 1.77μg/（kg·d） and 0.01 μg/（kg·d） to 0.26 μg/（kg·d）,respectively.The health risk index（HRI） of THg and MeH g exposure to the rice consumers of the rice has been disclosed ranging from 0.03 to 2.49（JECFA-recommended safety standards for THg）,and 0.04 to 1.13（JECFA-recommended safety standards for MeH g）,0.1 to 2.6（US EPA-recommended safety standards for MeH g）,respectively.Based on the assessment model,we have detected that the mass ratio of MeH g in the hair of the residents ranges from 0.17 μg/g to 3.11 μg/g,with only 5% of the monitoring points exceeding the JECFA-recommended value,whereas 38.33% of the monitoring points have gone beyond the US EPA-recommended standard.There remains a serious problem to be searched through as to whether the trend of the said mercury pollution and the risk is declining or ever-increasingly intensified with the increase of the distance from the Hg-mining area.As a result,the consumption of the rice has become a critical pathway or channel of mercury exposure to the local rice consumers,who have to be the victims of such potential health risks.Furthermore,the risk levels are closely associated with the location of the rice cultivation.Nevertheless,for the time being,the risks of THg and MeH g exposure can be regarded as being within the controllable extent,and therefore we would like to propose that timely measures be taken to avoid further extension of such risk threats to the local rice consumers.