In Greek Mythology, the Trojan Horse (hiding a select force of men), enabled the Greeks to gain entrance into Troy during the Trojan War. Metaphorically a “Trojan Horse” has come to mean any act of subterfuge that causes the target to invite a foe into a securely protected place; a phrase that is now associated with tiny pieces of plastics (microplastics) that find their way into our urban rivers every day. Microplastics are believed to influence the movement of chemicals in the aquatic environment by mobilising chemicals contained within sediments by binding them onto their surfaces. The plastics, being small and mobile, may be ingested by a range of benthic organisms, and release their biologically active payload inside the body to affect health. This project will combine state-of-the-art methodology and expertise from Brunel University London and Queen Mary University of London to (i) understand how microplastics interact with sediment, influence the mobility, partitioning and bioavailability sediment-associated contaminants and how this may be influenced by sediment composition, and (ii) to determine whether exposure to microplastic ‘Trojan Horses’ can alter the behaviour, reproduction and expression of relevant biomarker genes in live snails. Laboratory exposures, using the mud snail Potamopyrgus antipodarum, will be used to develop a greater understanding of the role of microplastics on the distribution and bioavailability of known sediment-bound contaminants. There may also be opportunities to utilise field studies and catchment modelling approaches to determine the best management options through working with project partners Thames21 and other stakeholders.