宣威街道尘中重金属的分布特征及其健康风险评估

Distribution Characteristics of Heavy Metals in the Street Dusts in Xuanwei and Their Health Risk Assessment

云南肺癌高发区(宣威)的环境污染与人群健康之间的关系一直是环境科学研究领域的热点之一.本研究采集了宣威市电厂及其上风向地区和下风向地区的街道灰尘,利用ICP-MS对样品中的重金属元素进行了分析;利用富集因子法对样品中的重金属污染及来源进行探究;并运用美国环境保护署(US EPA)发布的人体暴露风险评价方法对样品中重金属元素的健康风险进行了评估.结果表明,宣威街道尘土中Al、V、Ni、Co、Zn和Cd等金属元素的质量浓度明显呈"电厂>来宾>倘塘"的特征;V、Cd、Cr、Cu、Mn、Co、Ni、Pb、As和Zn等10种重金属的含量明显高于云南省土壤背景值,显示宣威市地表灰尘重金属污染较为严重;宣威街道中Cr、Cu、Zn、Pb、As和Cd等重金属主要来源于电厂排放的燃煤颗粒物.健康风险评估的结果表明,宣威街道灰尘中10种重金属元素对儿童的非致癌风险大于成人,手-口摄入是灰尘重金属暴露的主要途径;宣威街道尘土中Cd、Cr、Ni、Co和As等5种致癌重金属存在潜在的致癌风险;Cr是威胁儿童健康的主要污染因子.

Relationship between high lung cancer incidence in Xuanwei residents and environmental pollution has been a hot topic in the field of environmental sciences. Street dusts in Xuanwei power plant area as well as its upwind area (Banqiao town) and downwind area (Laibin town, Tangtang town) were collected. Chemical elements in the street dust samples were investigated using ICP-MS. Health risk assessment of heavy metals in the street dusts was carried out using the US EPA Health Risk Assessment Model. Our results showed that the mass level of Al, V, Ni, Co, Zn and Cd in street dusts followed the order of Xuanwei power plant ﹥ Laibin town ﹥Tangtang town. The mean concentrations of V, Cd, Cr, Cu, Mn, Co, Ni, Pb, As and Zn were all higher than the background values in Yunnan soil, indicating that the street dusts of Xuanwei city have been heavily polluted by those metals. The health risk assessment results showed that the non-cancer hazard risks induced by the 10 heavy metals were higher to children compared to adults. The heavy metals in street dust were mainly ingested by human bodies through hand-mouth ingestion. The 5 carcinogenic metals, including Cd, Cr, Ni, Cr and As, had a potential risk of carcinogenicity in human after exposed to the dusts. Cr was the major toxic element to the local children’s health.