Bioaccessibility and source-specific health risk of heavy metals in PM2.5 in a coastal city in China

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Heavy metals in PM2.5 (a global pollutant) are bio-accessible and highly toxic. Health risk assessment of bioaccessible heavy metals in PM2.5 was analyzed in the present study to relate the bioaccessibility with health outcomes. Then source-specific health risk was used to find out the major health abuser, which could provide reliable evidence for accurate pollution control. PM2.5 samples were collected in four seasons included spring, summer, autumn, and winter in urban and suburban areas in Xiamen, China. The order of heavy metals’ concentrations in PM2.5 was Cu > Zn > Mn > Ni > Pb> V > Co > Cr, urban area > suburb. Heavy metals in PM2.5 were mainly from anthropogenic sources that contributed more than 69.30%, 56.51%, 69.70%, 58.99% in spring, summer, autumn, and winter, respectively. Bioaccessibility of V, Pb, and Zn was relatively high, Co, Ni, Mn was relatively low after extracting by an artificial lysosomal fluid at pH=4.5. Bioaccessibility of Cr in spring and summer was higher than that in autumn and winter (60.4%–90.7% vs. 16.1%–69.2%) due to different sources and species in various seasons. Bioaccessibility of Cu after 1 d extraction was higher than that after 15 d extraction (69.6%–78.4% vs. 33.8%–48.2%) because of reverse adsorption of filter membranes and particulate matter. Health risks of bioaccessible heavy metals were lower than those of total heavy metals. However, both total and bioaccessible Cr and Cd had carcinogenic risks. Based on the combined positive matrix factorization-health risk (PMF-HR) model, industry, combustion, and traffic emission contributed the most to the health risk of Cr and Cd, followed by soil parent material layer. Our study provided a reliable method to calculate the bioaccessible heavy metal health risk and determine each potential source's contribution to health risk.