基于健康风险评价的白菜种植土壤中重金属的安全限量研究

解决蔬菜的食用安全问题需要从源头上进行控制,针对主栽蔬菜品种制定相应的种植土壤重金属安全限值是保障蔬菜食用安全的有效手段。本文基于健康风险分析,根据可接受健康风险水平、我国一般人群的蔬菜摄入量和所含重金属在膳食摄入总量中的占比,反推出保障人体健康不受危害的最低蔬菜摄入重金属的安全浓度。搜集大量研究数据,拟合白菜吸收富集重金属的回归方程,确定了白菜种植土壤中类金属As和重金属Cd、Cr、Cu、Ni、Pb、Zn、Hg的安全限值。我国人群膳食摄入中由蔬菜摄入贡献的重金属在12%~43%不等,在不同区域膳食摄入差别较大,相同区域不同重金属间差异较大。蔬菜中具有致癌毒性的As和Cr的安全限值分别为0.04 mg·kg^-1和0.17 mg·kg^-1,低于《食品安全国家标准食品污染物限量》(GB 2762-2017);白菜种植土壤中As、Cr和Pb的安全限值分别为26、16 mg·kg^-1和51 mg·kg^-1,低于《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB 15618-2018),其他5种重金属的安全限值则比国家标准更高。基于可接受人体健康风险推算的白菜产地重金属安全限值与我国现行土壤标准的比较,白菜产地依据重金属种类的不同应该有更低或更高的土壤重金属标准限值。因而建议针对具体的蔬菜种类制定相应的种植土壤标准。

Safety limits of heavy metals in planted soil of Chinese cabbage based on health risk assessment

To ensure the safe consumption of vegetables, it is important to control pollutants at the growth source by setting species-specific safety limits for heavy metals in the planting soil. In this study, the maximum acceptable concentrations of metalloid As and heavy metals Cd, Cr, Cu, Ni, Pb, Zn, and Hg in vegetables were determined on the basis of acceptable health risk levels, daily vegetable intake, and the proportion of heavy metals in the vegetables against the total dietary intake for the general population in China. Large amounts of research data were collected to fit the absorption and enrichment equation of each element contained in Chinese cabbage plants, and the safety limits for these elements in the planting soil were determined. The results showed that the vegetables contributed 12% to 43% of heavy metals in the dietary intake, with the proportions differing among the elements. With the exceptions of As, Cr, and Pb, the estimated safety limits of heavy metals in vegetables were higher than those specified by the National Food Safety Standard Contaminant Limit in Food(GB 2762-2017). The estimated safety limits of As(26 mg·kg^-1), Cr(16 mg·kg^-1), and Pb(51 mg·kg^-1)in the Chinese cabbage planting soil were lower than the corresponding limits set by the National Risk Control Standard for Soil Contamination of Agricultural Land(GB 15618-2018). Therefore, it is necessary to develop soil standards for specific vegetable species.