苏州市不同区域水稻籽粒重金属积累特征与健康风险评价

以苏州市7个县市的水稻籽粒为研究对象，在2006年采集的449份水稻籽粒样品的基础上，分析了稻米中Cu、Pb、Cd、Cr和Zn的积累特征，并评价了样品的健康风险。结果显示，苏州市水稻籽粒重金属积累平均含量均不超标，但水稻籽粒Pb存在29．49％的样点超标率，Cu、Cd和Cr的超标样点一般在4个以下。单因子污染指数评价结果显示，水稻籽粒重金属元素污染指数高低顺序为Pb＞Cr＞Cu、Zn＞Cd，其中昆山和吴江水稻籽粒受到Pb的轻度污染。综合污染指数评价表明，水稻籽粒重金属污染处于警戒线级别，且水稻籽粒的污染是由于Pb的积累量较高引起的，其中太仓和张家港两市水稻籽粒属于安全等级，昆山、吴中、相城和常熟处于警戒线等级，吴江风险较高。暴露风险评价结果显示，研究区存在水稻籽粒Cr暴露风险，而水稻籽粒Pb仅在个别县市暴露风险高，整体风险并不高。

Heavy Metal Accumulation Characteristics and Risk Assessment of Rice Grain in Different Regions of Suzhou City, China

In order to concern about food safety of rapidly developing regions in China, 449 rice grain samples were collected from 7 counties of Suzhou City in 2006. The contents of Cu, Pb ,Cd, Cr and Zn in rice grain samples were analyzed. According to relative national standards of China and human health risk assessment, pollution and safety of rice grain in study area were evaluated. Average heavy metal concentration in rice grain did not exceed the national critical limit in Suzhou City. Excessive Pb accumulation in rice grains was a problem faced by the city. The percentage of sites that exceeded the critical limit was 29.49% for Pb in Suzhou, and most of those sites were close to the industries. Less than four sites exceeded the critical limit for Cu, Cd, and Cr. The results by single element assessment for the pollution indexes indicated that Pb〉Cr〉Cu〉Zn〉Cd. For the administrative regions under Suzhou, rice grain Pb accumulation in Kunshan and Wujiang were classified as slight pollution. Synthesis assessment indicated that rice grains were at risk of pollution in Suzhou. Excessive Pb accumulation was responsible for the pollution of rice grains. Rice grains were classified as safety in Taieang and Zhangjiagang, at risk in Kunshan, Wuzhong, Xiangcheng and Changshu, and slightly polluted in Wujiang. Risk assessment showed that rice grains in all soils of the region pose some Cr exposure risk to food safety and rice from some area was at Pb exposure risk. Fortunately, it still fell into the safe category.