Bioaccessibility and Health Risk Assessment of Heavy Metals in Dust of the Urban Areas of Guiyang, Guizhou, China

To investigate what health risks the heavy metals in dust will bring to the human body after they enter humans through different exposure pathways- breathing inhalation and hand-to-mouth ingestion, this study took the old urban area of Guiyang as the study area to grasp the heavy metal concentrations of surface dust, in recreative squares main streets, hospitals, residential areas, and schools in the urban area, and the bioaccessibility in the simulated lung and simulated gastrointestinal. The results showed that the concentrations of Cu, Pb, Zn, Cd, Ni, and Cr in the dust were higher than the background values. Particularly, the Zn concentration exceeded the background value by 9.71 times. The bioaccessibility results indicated that the most soluble heavy metals in the simulated lung, simulated stomach, and simulated intestine were Zn, Ni, and Cu, respectively, and the bioaccessibility of most heavy metals was significantly higher in the gastric phase than that in the intestinal phase, and only the bioaccessibility of Cu was higher in the intestinal phase than that in the gastric phase. The linear results fit showed that the total amount of heavy metals alone could not be used for predicting 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 in terms of both hand-to-mouth ingestion and respiratory inhalation exposure pathways, but none of these figures exceeded the limit values.