基于蒙特卡罗模拟的土壤环境健康风险评价:以PAHs为例

Environmental Health Risk Assessment of Contaminated Soil Based on Monte Carlo Method: A Case of PAHs

为获得更为合理的健康风险评价结果,并辨识对健康风险影响最大的因素,基于蒙特卡罗随机模拟,运用概率风险评价模型,定量评估了中国上海某居民区土壤中16种PAHs对居民的健康风险水平,并对各参数进行敏感性分析.结果表明,土壤中PAHs造成的健康风险服从对数正态分布,总的致癌风险为3.43×10^(-5)±2.63×10^(-5),最小值为8.10×10^(-7),最大值为2.39×10^(-4),超过10-6的概率为95%,超过10^(-5)的概率为75%,超过10^(-4)的概率小于5%;总的危害商为4.74×10^(-2)±3.42×10^(-2),不超过1,风险较小;在7种具有致癌效应的PAHs中,苯并(a)芘、二苯并(a,h)蒽和苯并(a)蒽是总致癌风险的主要贡献物质,贡献率分别占60.41%、26.84%和6.56%;3种暴露途径中,经口途径是造成致癌风险的主要途径,贡献率为73.22%;对于总致癌风险,人体暴露参数中每日土壤摄入量、暴露周期、暴露皮肤面积敏感度较大,分别为58.35%、50.21%和20.51%;体重具有负敏感性,敏感度为-11.66%.

In order to obtain more reasonable health risk values and get the most significant factors, probabilistic risk models based on Monte Carlo simulation were applied, the health risk level of 16 PAHs in soil was evaluated for a residential area in Shanghai, China. And, sensitivity analysis was conducted for each parameter. The results showed that, the health risks caused by PAHs followed lognormal distribution with 3.43×10-5±2.63×10-5 for carcinogenic risk, which was between 8.10×10-7 and 2.39×10-4 and the probabilities exceeding 10-6, 10-5 and 10-4 were 95%, 75% and less than 5%. And the value was 4.74×10-2±3.42×10-2 for hazard quotient, which was between 1.38×10-3 and 2.85×10-1 and less than 1, so could be regarded negligible. As for total carcinogenic risk （TCR）, the most influential PAHs were BaP, DBA and BaA, and their contribution rates were 60.41%, 26.84% and 6.56%, respectively. Among the three exposure pathways, the risk was mainly caused by oral intake with the contribution rate of 73.22%, followed by dermal contact with 26.51%. The most influential parameters were：intake amount of soil per day, exposure duration and exposed skin area with the sensitivity values of 58.35%, 50.21% and 20.51%, respectively. And body weight had a negative sensitivity with -11.66%. When it came to total hazard quotient （THQ）, Pyr, FL and PA accounted for the most with 36.56%, 33.18% and 13.18%, respectively. And the oral intake and dermal contact were also primary exposure pathways with 72.21% and 26.36%. The most significant parameters were the same with TCR with the sensitivity values of 63.52%, 53.18%, 24.39% and -13.98%, respectively.