土壤重金属的健康风险评价及其参数不确定性的量化研究

基于美国环保署现行健康风险评价体系的理论、方法和实例污染场址情景构建了土壤重金属污染的多途径健康风险评价模型，而后利用Monte-Carlo模拟法和敏感度分析技术初步量化研究了评价中参数不确定性的影响程度，并筛选得出相关敏感参数.结果表明：确定性评价下实例区域土壤中Cd和Ni的非致癌风险（HI）均小于1（HICd＞HINi），对目标受体暂时不会造成非致癌健康风险；而Cd的致癌风险（RCd）大于1.0×10-6，已可能对目标受体造成致癌风险；在参数Monte-Carlo模拟的辅助下，参数不确定性对于非致癌风险值的影响波动在0.1~0.2以内，而其引起致癌风险值的波动在1个数量级以内，实例中RCd的模拟值区间横跨1.0×10-6，可能误导决策；敏感度分析结果表明应重点对实例区域蔬菜和土壤中的Cd浓度及区域目标受体体重这3个敏感参数进行资料搜集，如此可以在有效提高风险评价可信度的同时降低不必要的预算开支.
Based on USEPA framework of health risk assessment, the multi-pathway health risk assessment model was developed for heavy metals in the case soils. Monte-Carlo simulation was adopted to quantitatively study the effect degree of parameter uncertainty on assessment result, and sensitive parameters were further identified by sensitivity analysis. The results without Monte-Carlo simulation showed that there was no non-carcinogenic risk because of 1＞HICd＞HINi while it was under carcinogenic risk due to RCd＞1.0×10-6. However, with the Monte-Carlo simulation of selected variables, it indicated that the parameter uncertainty made the non-carcinogenic risk assessment results varying within 0.1~0.2, and the carcinogenic risk assessment results varying in the range within 1 order of magnitudes. Therefore, the parameter uncertainty made the value range of RCd span 1.0×10-6 and it was probable to mislead the corresponding decision-making. Sensitivity analysis indicated that the contents of Cd in case soils and vegetables, and the weight for the target receptor should be treated as sensitive variables, which were the main source of parameter uncertainty. To further improve the credibility of assessment with cost-benefit consideration, data of the sensitive variables should be preferentially gathered.