Uncertainty model for the health risk of heavy metals in urban topsoil and dust based on blind number theory
基于盲数理论的城市表土与灰尘重金属污染健康风险评价模型

Based on the characteristics of concomitancy of multiple uncertainties in environmental health risk system, the blind number theory was introduced to the assessment of human health risk. Blind number models were developed to calculate exposure dose and characterize the health risk of heavy metals, and a classification model for cancer risk was put forward as well. As a case study, the models established were applied for health risk assessment of Pb, Zn, Cr, As, Cu, Ni and Cd in urban topsoil and dust of Tongling City. And possible values and their corresponding credible degrees of cancer and non-cancer risks were calculated simultaneously for the measured heavy metals. The results showed that the total expected value of non-cancer risk for the seven metals reached 2.036, far exceeding the safety threshold value 1.0. Especially for As, the non-cancer risk through ingestion of dust particles approached 1.438. In general, the expected value of non-carcinogenic risk for the measured seven metals decreases in the order of As>Cr>Pb>Cu>Cd>Ni>Zn. Regarding carcinogen effects, the highest risk for As is associated with ingestion of dust particles and its overall expected value reached 5.195×10-4, far exceeding the upper limit (1.0×10-4) recommended by the United States Environmental Protection Agency (USEPA). In addition, the carcinogen risk for As through dermal contact with dust particles was also high, expected as 3.964×10-5 close to the highest acceptable risk value 5.0×10-5 proposed by the International Radiation Protection Association (ICRP).