Bioaccessibilities and health risk assessment of heavy metals in dust from the Guizhou-Guiyang urban zone, China

To investigate the health risks of heavy metals in dust entering the human body from different exposure pathways. In this study, the old urban area of Guiyang was used as the study area to understand the heavy metals concentrations in surface dust, including recreational plazas, main streets, hospitals, residential areas, and schools in this city, and the bioaccessibility in the simulated lung phase and simulated gastrointestinal phase. The results showed that the concentrations of Cu, Pb, Zn, Cd, Ni, and Cr in the dust were higher than the background values, especially the Zn content exceeded the background value by 9.71 times. The bioaccessibility results indicated that the most soluble heavy metals in the simulated lung phase, simulated gastric phase, and simulated intestinal phase were Zn, Ni, and Cu, respectively, and the bioaccessibility of most heavy metals was significantly higher in the gastric phase than in the intestinal phase, and only Cu was higher in the intestinal phase than in the gastric phase. The linear results fit suggested that the total amount of heavy metals alone could not predict the human intake of heavy metals in the dust. Human health risk assessment based on bioaccessibility showed that children had higher non-carcinogenic and carcinogenic risks than adults for both hand-to-mouth ingestion and respiratory inhalation exposure pathways, but none of them exceeded the limit values.