Source, bioaccessibility and oral exposure risk assessment of rare earth elements in soils with typical land-use...

The rare earth elements (REEs) are strategic elements extensively utilized. Accurate exposure risk assessment is crucial for managing potential health hazard associated with soil REEs. However, existing exposure assessments inadequately consider the effects of bioaccessibility and land-use type on risk levels. This study collected soil samples from areas with distinct land-use types to measure REEs concentration and bioaccessibility, and then assessed non-carcinogenic and carcinogenic exposure risk based on bioaccessibility using Monte Carlo simulation. The results indicated that total REEs concentrations ranges from 71.2 to 220.2 mg/kg, and the highest value was found in petroleum refinery soil. The bioaccessibility of REEs ranges from 0.3 % to 1.9 %, and the highest value was found in light industry area soil. Distribution patterns of REEs suggest that primary sources of soil REEs are parent materials of soil in this study such as granite and Alkaline basalt, and anthropogenic activities such as emission of petroleum refining, fertilizers and atmosphere particle depositions, both of which are associated to land-use type. Exposure risk assessments indicate that non-carcinogenic and carcinogenic exposure risk is acceptable for children and adults. Among the soils, urban park soil has the highest exposure risk, whereas Tibet plateau soil in residential area has the lowest. The bioaccessibility and concentration of REEs in soil are primary factors influencing risk, followed by exposure time. This study indicates that the exposure risk of soil REEs is associated with bioaccessibility and land-use type, aiding in the prediction and management of potential health risks associated with soil REEs.