Suspected microplastics in Atlantic horse mackerel fish (Trachurus trachurus) captured in Portugal

Microplastics have been found in fish, but most studies have focused on the digestive system without considering additional organs. Herein, the objective was to assess the presence of microplastics in internal organs (gills, guts, kidney, heart) of the Atlantic horse mackerel (Trachurus trachurus) captured of the coast of Portugal (Northeast Atlantic Ocean). Suspected microplastics were present in all organs, with particles of larger size (i.e., equivalent diameter) found in the gut and those of lower size in the heart and its luminal blood. Suspected microplastics of 1-10 μm were the most abundant (65.4%), more likely to translocate, owing to their minute size, but more difficult to properly characterize. These results highlight the need to expand the analytical work on organs and tissues for assessing microplastics in organisms, but also emphasize the actual need for developing analytical methods that allow for an accurate isolation, identification, and characterization of microplastics in biota.