Abstract Global contamination of aquatic ecosystems by synthetic microparticles has raised increasing concern, yet studies on their ingestion by freshwater invertebrates remain limited. Benthic macroinvertebrates, highly exposed to this kind of contamination, play a key role in aquatic food webs and nutrient cycling. This study investigated the ingestion of synthetic microparticles by benthic macroinvertebrates in the middle Tietê River basin, widely recognized as one of the most polluted rivers