A global perspective on exposure and data gaps for microplastic contaminants in bivalves and cephalopods

Edible mollusks are a significant global cultural and economic aquaculture species critical in preserving healthy ecosystems. During their lifetime, they may be exposed to different microplastics (MPs) acting as a chemical carrier for variable organic pollutants. We aim to highlight the challenges of analyzing the potential co-transfer of PAHs, PCBs, and PFASs from the marine environment, with microplastics serving as their vectors, to edible marine mollusks (mussels, oysters, scallops, clams, octopuses, cuttlefish, and squids) based on available literature. To this end, we compiled concentrations of hydrophobic pollutants detected on the surface of microplastics collected globally at different marine sites. As a next step, we searched for studies that showed how high concentrations of MPs can be found in mollusks to show geographical differences between them. We identified areas with the highest potential exposure and knowledge gaps that require further investigation. Papers contain data on PAHs, PCBs, PFASs on microplastics collected mainly from the beach or surface water. While the two first groups have good representation with 189 and 156 data points, respectively, data on PFASs is highly underrepresented. These findings suggest that there is a significant gap in data for assessing the adsorption-desorption behavior of environmentally relevant types of MPs frequently ingested by mollusks. The limited data on cephalopods, compared to bivalves, also reveals important gaps in trophic and ecological risk assessments. This study underscores the need for harmonized monitoring of MPs and associated contaminants across diverse taxa and regions.