南方6省稻米总汞含量调查及其膳食暴露评估

为评价中国南方6省稻米中总汞污染现状,于2009年在江西、湖北、湖南、广东、广西和四川6省抽样检测了1 321份稻米样品,结合中国居民20个性别年龄组人群的稻米消费量和体重信息,采用非参数概率方法对稻米中总汞的膳食暴露量进行了评估。总汞含量采用电感耦合等离子体质谱仪（ICP-MS）测定,检出限（LOD）为0.000 8 mg.kg-1。结果表明,稻米的总汞含量在地区间存在着差异,虽然有76.2%的样本总汞含量（0.000 8～0.063 4 mg.kg-1）高于检出限,但仅有2.3%的样本超出了最高限量（ML 0.02mg.kg-1）。将评估结果比照JECFA推荐的总汞暂定每周耐受摄入量（PTWI）5μg.（kg bw）-1,我国居民食用这6省稻米产生的汞暴露风险较小。但在P99.9的高百分位水平下,14岁以下人群的摄入量相对较高,占PTWI的41.5%～62.9%,其中2～4岁儿童和4～7岁男童的摄入量占PTWI的60%以上,潜在风险较大。建议应对稻米中重金属汞的含量进行追踪监测。

Survey and Dietary Exposure Assessment of Total Mercury in Milled Rice Farmed in 6 Provinces of Southern China

The study aims to investigate the occurrence of total mercury in milled rice from 6 provinces of Southern China during harvest in 2009,and determine the dietary exposure of target population using a non-parameter probabilistic model with information on rice consumption and body weight.Altogether 1 321 milled rice samples were collected from Jiangxi,Hubei,Hunan,Guangdong,Guangxi and Sichuan Provinces.Total mercury was measured by inductively coupled plasma-mass spectrometry（ICP-MS）,and the limit of detection（LOD） for it was 0.000 8 mg·kg-1.The analytical results showed that 76.2% of the samples contained detectable concentrations of total mercury,which ranged from 0.000 8 to 0.063 4 mg·kg-1,but levels were generally low,with only 2.3% of the samples having concentrations above 0.02 mg·kg-1,the maximum level（ML）.On the other hand,there was an apparent regional difference found for the concentrations of total mercury in milled rice.The provisional tolerable weekly intake（PTWI） of mercury,as recommended by Joint FAO/WHO Expert Committee on Food Additives（JECFA） is 5 μg·（kg bw）-1.The estimated exposure values for populations of interest were compared to the PTWI.For the relevant population,this study confirmed the low probability of health risks from total mercury via the milled rice from the 6 provinces of Southern China.But exposure to total mercury for the population below 14 years old at P99.9 represented 41.5%～62.9% of the PTWI.While for children aged 2～4 years and boy aged 4～7 years,their estimated exposure at P99.9 were all over 60% of the PTWI.Considering the potential risk,this study suggests that a yearly monitoring program for total mercury in milled rice is necessary.