Characteristics of Heavy Metal Pollutants of PM2.5 from Open Burning of Municipal Solid Waste (MSW) and the Associated Exposure Health Risks

: The characteristics and health risk assessment for heavy metal pollutants in PM2.5 discharged from the open burning of municipal solid waste (MSW) in different functional areas were studied using a flue gas diluted sampling system. The two common open burning modes of barrel and natural pile-up burning were considered. The results show that the concentration of zinc (Zn) was the highest among the heavy metals produced by five different components of waste incineration, ranging from 1324.03 to 3703.12 mg·kg-1. The concentration of cadmium (Cd) was the lowest, ranging from 20.25 to 63.68 mg·kg-1. According to the geo-accumulation index, lead (Pb), Zn, arsenic (As), and Cd were highly polluted in the measured MSW samples, and all four of these metals reached moderate or higher levels of pollution under natural pile-up burning methods. The geo-accumulation index of Cd was much higher than 5. The results of the human health risk assessment showed that non-carcinogenic risk values for 8 heavy metals (Pb, Zn, Cu, Mn, As, Cd, Cr, and Ni) by respiratory exposure were less than 1, which is within the safe range. For natural pile-up burning, the total non-carcinogenic risk values for As and Pb for children were higher than 1, indicating a non-carcinogenic risk. The carcinogenic risk values for four carcinogenic elements (As, Cd, Cr, and Ni) were less than 1.0×10-4, but still represented a low potential carcinogenic risk under exposure for long periods of time.