Microscopic plastic (MP) particles are ubiquitous contaminants in aquatic environments and have become a major environmental issue in recent years. These particles consist of many different plastic types, which co-occur with and can sorb hydrophobic organic chemicals (HOCs), such as polycyclic aromatic hydrocarbons (PAHs) or polychlorinated biphenyls (PCBs), altering their environmental fate. MP-HOCs could be transferred from MPs to biota either via desorption to an aqueous phase e.g. external environment or intraorganismal fluid, or via direct contact with epithelia e.g. gill or gut. Only a few studies on MPs <100 micrometers have been carried out and there is an urgent need to assess the risk they pose to aquatic biota.
In vitro assays play a key role in ecotoxicology for risk assessment. This proof-of-principal project aims to employ cultured rainbow trout gill (RTgill-W1) and intestinal (RTgutGC) epithelial cells, with potential to progress to human cell lines, to study whether the co-occurrence of MPs and HOCs alters their toxicity profile. A suite of cellular damage endpoints will be applied, including cytotoxicity, genotoxicity and oxidative stress. Target gene expression profiling will help to identify genes/pathways that can be related to initial toxic and adaptive cellular responses in order to better understand underlying mechanisms of (geno)toxicity. Hence, the project will advance our knowledge on what environmental risk MPs-HOCs pose. In situ sampling in urban streams and/or the Thames estuary will complement the in vitro studies, to directly correlate MP uptake and HOCs present in fish and/or filter feeding bivalves in UK waters and examine whether there is a vector effect.