Microplastic contamination in drinking water sources and distribution networks of a Western City in Iran

Microplastic contamination has become a widespread environmental issue, prompting extensive research into its potential health and ecological impacts. This study investigates the occurrence, characteristics, and seasonal dynamics of microplastics in the drinking water supply system of Khorramabad, Iran, and evaluates associated exposure risks.

Water samples were collected from 55 strategic locations-including wells, springs, and inlets/outlets of treatment plants-across the city's distribution network during the wet (April, May) and dry (August, September) seasons of 2023. Microplastics were detected and quantified using density separation techniques, with µ-Raman spectroscopy employed to determine their polymer composition.

The results revealed an average microplastic concentration of 2.06 MPs/L, with white fibers ranging from 250 to 5000 μm being the most prevalent morphology. The dominant polymer types identified included polyethylene (PE), polypropylene (PP), and polystyrene (PS). Seasonal analysis revealed a statistically significant increase in microplastic abundance during the wet seasons (P < 0.001), indicating that rainfall is a primary factor driving groundwater contamination. Spatial variability across sampling points was not statistically significant (P = 0.25). Based on the risk assessment, the drinking water in Khorramabad was classified as low-risk. However, despite the minimal risk posed by these polymers, their potential health impacts should not be overlooked.

This study highlights the need for improved monitoring, optimized treatment processes, and public awareness campaigns to mitigate microplastic pollution in urban water systems. This study is notably the first to investigate microplastics in drinking water within the western region of the country.