Microplastic and microcystin in tropical drinking water reservoir: pollution characteristics and human health risk...

The presence of microplastics (MPs) and cyanobacterial toxins (microcystin, MC) in drinking water is a growing public health concern. This study investigated their occurrence and distribution in a tropical reservoir from June 2023 to May 2024. MPs were found at all sites, with an abundance ranging from 1.3 to 38.0 items m^-3, predominantly fibers under 2000 μm. Polypropylene (PP), polyethylene terephthalate (PET), polyethylene (PE), and polyvinyl chloride (PVC) were the prevalent polymer types. The pollution load index of MPs was low (PLI = 2.6, level 1), but their high polymer hazard (PHI = 905.4, category IV) and ecological risk (PERI = 696.5, Danger) indicate potential environmental threats in Hoa Binh Reservoir. The MC toxin analyzed by high-performance liquid chromatography (HPLC) showed that total MC concentrations varied seasonally, with the highest value of 5.27 μg L^-1. Health risk assessment indicated that the overall risk from MCs in all sampling sites remains low (average HQ values of 0.14). This study confirmed the co-occurrence of MPs and MCs in all Hoa Binh Reservoir sampling locations during the entire study period, which could potentially favor the interaction between these contaminants. These findings highlight the need for more research on how MPs influence cyanotoxin, which is essential for developing effective water management and pollution control strategies in freshwater ecosystems.