Exposure of children to light rare earth elements through ingestion of various size fractions of road dust in REEs mining areas.

Road dust, contains enhanced amounts of light rare earth elements (LREEs) in rare earth industrial cities, which poses a serious health risk particularly to children. Road dust samples were collected from Baotou, the largest rare earth industrial city in northern China, and sieved into six size fractions. The pollution characteristics of the LREEs (La, Ce, Pr, and Nd) in the size-fractioned road dust were investigated, and the LREEs exposure dose of children via ingestion of road dust was evaluated. The results showed that the finer size fractions of road dust had enhanced REEs concentrations, and the pollution level was found to be elevated with a decrease in particle size. Ce was the most abundant element, with concentrations ranging from 105 to 5420 mg·kg-1, followed by La, Nd and Pr. REEs mining activities had a major contribution to the LREEs in the road dust and crust, among which coal combustion emissions could also be a potential source. The average daily intake dose of LREEs through ingestion of road dust by children ranged from 4.27 × 10-4 to 2.63 × 10-2 mg·kg-1·day-1 and was significantly affected by particle size. Road dust exposure is notably affected by particle size, and there is a serious risk to children of LREEs uptake from fine particles (<100 µm) of road dust.