长春市城区近地表灰尘重金属健康风险评价

为评价长春市城区近地表灰尘中重属污染特征及其健康风险,采用网格化均匀布点系统采集了232件长春市城区近地表(约1.5m)灰尘样品,分别采用X荧光光谱法(XRF)、原子荧光光度法(AFS)和石墨炉原子吸收光谱法(GF-AAS)测定了近地表灰尘中Cu、Pb、Zn、Cr、As、Hg和Cd含量.结果表明:城市近地表灰尘中As、Cd、Cr、Cu、Hg、Pb和Zn的平均含量分别为23.26、0.62、94.53、68.41、0.24、93.63和416.71mg/kg,且其变化范围较大,同时均显著高于研究区表层土壤重金属含量,已受到一定程度重金属污染.健康风险评价结果表明,儿童暴露剂量均明显高于成年人暴露剂量,是成人暴露剂量的7.3倍(As为7.9倍),经消化道摄入暴露是人体城市灰尘重金属暴露的最主要途径,其次是皮肤接触暴露;从各元素的健康风险指数(HI)来看,As的健康风险最高,其次依次为Cr、Pb、Cu、Zn、Cd和Hg;非致癌总风险指数平均值分别为1.11(儿童)和0.14(成人),表明长春市城区近地表灰尘金属污染已对儿童造成了潜在的健康风险,As对总风险的贡献最大.叠加后的致癌总风险指数平均值为6.35×10-5,超过了EPA的建议值,As污染是主要风险因素,但长春市城区近地表灰尘由重金属引起的致癌风险总体上尚可接受,不会对当地居民的身体健康产生较大危害,但应加强防范.

Study on health risk of potentially toxic metals in near-surface urban dust in Changchun City

An extensive survey was conducted to evaluate the health risk of potentially toxic heavy metals in near-surface urban dust environment of Changchun, P.R.China. 232samples were collected, using a systematic sampling strategy with a sampling density 3~5 composite dust samples (about 1.5m above the ground surface) per km2in urban sit. X-ray fluorescence spectroscopy (XRF), atomic fluorescence spectrophotometry (AFS) and graphite furnace atomic absorption spectrometry (GF-AAS) were employed to analyze the Cu, Pb, Zn, Cr, As, Hg and Cd concentration of urban dust, respectively. The results indicated that the mean concentration of As, Cd, Cr, Cu, Hg, Pb and Zn in the near-surface urban dusts of Changchun was 23.26, 0.62, 94.53, 68.41, 0.24, 93.63 and 416.71 mg/kg, respectively, which are significant higher than the value of Changchun topsoils, meanwhile, which also shows that the urban dust in Changchun was polluted. The results of health risk assessment showed that children has had greater health risks than adults, the exposure doses for children were 7.3 times higher than those for adults, except for As which is 7.9 times higher. The exposure pathway which resulted in the highest level of risk for human exposed to near-surface dust was ingestion of this material, which was followed by dermal contact. As for the aggregate non-carcinogenic health risk (HI), As was of most concern regarding the potential occurrence of health impact, which was followed by Cr, Pb, Cu, Zn, Cd and Hg. The average non-carcinogenic health risk index for children and adults were 1.11 and 0.14, respectively. Of the three carcinogenic metals concernedin present study As, Cr and Cd, As was of most concerned. The average aggregate carcinogenic health risk index (RISKt) was 6.35×10-5, which was higher than the EPA advised values. However, except for some locations, risk values of both cancer and non-cancer health risk obtained in present study were in the receivable range on the whole.