Waste dumps as microplastic hotspots: a comparative investigation at urban, suburban, and rural areas of Eastern India and associated risk assessment

Microplastics (MPs) pollution has recently garnered substantial attention worldwide due to their tendency to contaminate ecosystems and transmit toxic substances in the food chain, compromising human health. The primary goal of this study is to provide a level of understanding about the source, occurrence, detection, and potential ecological risk of MPs in Eastern Indian dumping sites in the years 2022 and 2023 as well as representing a scenario encompassing urban, suburban, and rural areas. The MPs concentrations in dumping sites ranged between 10 and 3,457 MPs mg/kg. Fragments were the predominant shape in samples from both years, 32% and 36% in 2022 and 2023, respectively. White was the leading color of MPs in both years (34% in 2022, 45% in 2023), followed by gray, blue, green, and others. Based on the chemical analysis, the most common polymers discovered were polyethylene (20%), nylon (15.5%), polyethylene terephthalate (11.62%), and polypropylene (10.28%). Most of the study area has high polymer hazard index values (>1,000) due to the presence of high-hazard polymers like polyvinyl chloride and polyurethane. According to polymer load index (PLI) values, the samples from English Bazar and riverside dumps are highly contaminated with MPs (PLI: 26 to 49), whereas samples from Manikchak and Old Malda are less contaminated (PLI: 1 for both). The ecological risk index (ERI) values of riverside samples were the highest (ERI: 318950).