A multifaceted assessment of the effects of polyethylene microplastics on juvenile gilthead seabreams (Sparus aurata).

Plastic pollution has become a major environmental and societal concern in the last decade. From larger debris to microplastics (MP), this pollution is ubiquitous and particularly affects aquatic ecosystems. MP can be directly or inadvertently ingested by organisms, transferred along the trophic chain, and sometimes translocated into tissues. However, the impacts of such MP exposure on organisms' biological functions are yet to be fully understood. Here, we used a multi-diagnostic approach at multiple levels of biological organization (from atoms to organisms) to determine how MP affect the biology of a marine fish, the gilthead seabream, Sparus aurata. We exposed juvenile seabreams for 35 days to spherical 10-20 µm polyethylene primary MP through food (Artemia salina pre-exposed to MP) at a concentration of 5 ± 1 µg of MP per gram of fish per day. MP-exposed fish experienced higher mortality, increased abundance of several brain and liver primary metabolites, hepatic and intestinal histological defects, higher assimilation of an essential element (Zn), and lower assimilation of a non-essential element (Ag). In contrast, growth and muscle C/N isotopic profiles were similar between control and MP-exposed fish, while variable patterns were observed for the intestinal microbiome. This comprehensive analysis of biological responses to MP exposure reveals how MP ingestion can cause negligible to profound effects in a fish species and contributes towards a better understanding of the causal mechanisms of its toxicity.

Assessment of metal, metalloid, and radionuclide bioaccessibility from mussels to human consumers, using centrifugation and simulated digestion methods coupled with radiotracer techniques.

The dietary bioaccessibility of seven elements ((241)Am, Cd, Co, Cs, Mn, Se, and Zn) in the Mediterranean mussels Mytilus galloprovincialis (Lamarck, 1819) was assessed for human consumers. In this respect, we assessed and compared the proportion of elements associated with the cellular cytosolic ("soluble") fraction vs. the bioaccessible fraction derived, respectively, from (1) the differential centrifugation method and (2) the simulated digestion method. Comparisons were carried out on both raw and cooked mussels. Results showed that (1) the centrifugation method systematically underestimated (up to a factor 4) element bioaccessibility in raw mussels compared with the in vitro digestion method (e.g., 10% vs. 42% for (241)Am), and (2) the cooking process (5min at 200 degrees C) leads to concentrating the elements in mussel tissues (e.g., by a factor 2 for Zn) and reducing their bioaccessibility. Overall, the simulated in vitro digestion method appears as a powerful tool for seafood safety assessment and cooking could contribute in reducing substantially the global trace element intake from mussel tissues (up to 65% for Cd and Cs).