Abundance, characteristics, and potential human intake of microplastic contamination in tap water: A study of water supply treatment plants in Rayong Province, Thailand

Microplastics in drinking water pose global health concerns. This study investigated their occurrence, distribution, and potential human intake in water supply treatment plants in Rayong Province, Thailand. The fate of microplastics in the water supply system, from the source to household taps, was investigated. Microplastics were detected in all treatment plants, with concentrations ranging from 1.0 to 18.15 items/L in raw water and 0.51 to 11.20 items/L in treated water. Removal efficiency varied from 33.13 % to 63.12 %, influenced by particle size, shape, and polymer density. Fragments and fibers, particularly particles <250 μm, were most prevalent. The primary polymers identified were polyester (PEST), polyethylene terephthalate (PET), and polypropylene (PP). Notably, epoxy resin, polyacrylamide (PAM), polyvinyl chloride (PVC), and chlorinated polyethylene (CPE) were found in treated but not raw water, suggesting secondary contamination. Microplastic concentrations in household tap water were lower than in treated water, reducing exposure risk. Estimated daily intake (EDI) analysis indicated that infants had the highest exposure (0.355 items/kg BW/day), followed by adults (0.184–0.201 items/kg BW/day) and children (0.108 items/kg BW/day). These findings highlight widespread microplastic contamination, potential health risks, and the urgent need for enhanced treatment technologies and further research into long-term effects.