Microplastic contamination in edible invertebrate from seafood markets along the Egyptian Red Sea and Mediterranean Sea

Marine environments contain plastic debris that potentially elicits adverse effects in aquatic organisms. In Egypt, microplastic pollution has been recognized as a significant issue; however, risks associated with human consumption have not been fully elucidated. Here, we evaluated the frequency of occurrence, abundance, and distribution of microplastics (MPs) in edible marine invertebrates (mussel, shrimp, and crab) sold at markets along the Mediterranean and Red Sea coasts of Egypt. A total of 108 samples were collected from four markets distributed along the two seas Hurghada and Suez (Red Sea), and Port Said and Alexandria (Mediterranean Sea) in May 2021. MPs were recovered from the soft tissue of the sampled invertebrates in all locations. MP abundance differed significantly among species and sampling sites, with the highest mean concentration recorded in invertebrates from Suez. Regarding particle size, the 1000–5000 µm class was most frequent, followed by 500–1000 µm and 100–500 µm. Polymer identity was confirmed by Fourier-transform infrared (FTIR) spectroscopy, which characterized 263 of 268 candidate particles as synthetic polymers. In the Red Sea, polyethylene terephthalate was the dominant polymer, followed by polyethylene and polyamide. In the Mediterranean Sea, polyacrylonitrile was the dominant polymer, followed by polyamide and polyethylene. We conclude that species-specific feeding habits and habitat are key factors related to MP bioaccumulation in marine invertebrates. These findings improve our understanding of the risk MPs pose to marine ecosystems and to seafood consumers by demonstrating their widespread presence in commercially important invertebrates.