Occurrence and Health Risks of Trace Elements in Indoor Dust from Municipal Preschools in Thailand’s Eastern Economic Corridor: A Case Study of Rayong Province

Industrialization in Thailand’s Eastern Economic Corridor raises concern about children’s indoor exposure to trace elements. As, Cr, Ni, Pb, Cu, Zn, Fe, Mn, and K were determined by ICP-OES in <63 µm settled dust from elevated surfaces and in surrounding soils at 25 municipal preschools in Rayong Province: nine each in the petrochemical (PC) and vehicle, equipment, and electronics manufacturing (VE) areas and seven in a background area (BG). Dust Cu and Zn were 4–15 and 9–13 times their soil concentrations; mean enrichment factors exceeded 10 for Zn everywhere and for Cu in PC and VE. As was higher in PC and VE than in BG dust, Zn was highest in PC, and Mn in VE. An exploratory principal component analysis separated a Cu–Zn–Ni–As–Cr association, tentatively attributed to mixed anthropogenic inputs, from an Fe–Mn–K association consistent with soil-derived material. A screening-level assessment based on total concentrations and U.S. EPA exposure models gave element-specific hazard indices below 1 and cumulative cancer risks of 4.3 × 10−6 to 3.3 × 10−5. For Pb, which has no reference dose, children’s margins of exposure were below 1 at 15 out of 25 preschools under upper-bound assumptions, so neurodevelopmental effects cannot be excluded. Wet cleaning and hand hygiene are recommended as precautions.