The Health Risk Assessment of Heavy Metals in the Circumstance of Dust in Shanghai Urban Parks

Heavy metals, a kind of persistent toxic substance (PTS), were taken for the study in this paper. Dust samples (44 in total) were collected in 2006 in Shanghai urban parks. The concentrations of Cu, Pb and Zn in dusts were determined by atomic absorption spectrometer. The concentrations of mean metals in dust samples were in the order Zn > Pb > Cu, where Pb shows the greatest coefficient of variation. The concentrations of heavy metals in dust samples exceeded soil background values of Shanghai. According to the exposure models for heavy metal pollutants, human health risk was evaluated in Shanghai urban parks. Compared with the Netherlandish allowable level of human ingested toxic pollutants, the exposure dose of lead for children is nearly doubled in deposited dust in Shanghai urban parks. The pathway of direct ingestion is dominating for children exposed to PTS, which is more than 98% of the overall exposure dose, followed by the pathway of dermal contact and inhalation. It shows that the pathway of direct ingestion is the principal pathway for children exposed to PTS in deposited dust in Shanghai urban parks and the health risk of PTS for children should not be overlooked. Through statistical analysis of arcgis module, the corresponding distributions of Cu, Pb and Zn show an increasing trend towards inner ring road. By contrast with roadside dust samples, collected near the upper reaches of the Huangpu River, which was viewed as a region with less man-made pollution, the main sources of these elements in Shanghai urban parks were mainly derived from human activities, especially for traffic sources.