Coastal to Oceanic Comparison of Plastic Additive Accumulation in Northeast Atlantic Top Predator Sharks

Plastic litter has significantly increased in the last decades due to its excessive production and inefficient waste management, which has led to millions of untreated tons of plastic ending up in the ocean. Over time, plastic waste undergoes degradation and can release various additives into the environment, including plasticisers, flame retardants, and other chemicals. Some have been classified as concerning for human health and environmental safety, such as phthalic acid esters (PAEs), used as plasticizers in plastic materials, and polybrominated diphenyl ethers (PBDEs), historically used as flame retardants. This study aimed to establish a profile of the most prevalent PAEs and PBDEs in the marine environment and to assess spatial differences between coastal and open-ocean areas by evaluating the accumulation patterns of these compounds across different tissues in a top predator, the blue shark (Prionace glauca), caught in offshore and coastal waters. A total of 34 blue sharks were opportunistically sampled as bycatch in the North Atlantic, with muscle and liver tissues collected in situ. In total, 8 different phthalates and 26 different PBDE congeners were quantified. The results show differences in PAEs concentrations between coastal and oceanic catches across both tissues analysed (p < 0.05), as well as differences in PBDEs in the liver (p < 0.05), but not in muscle (p = 0.084). Furthermore, both tissues exhibited significant differences in the concentrations of the two plastic additives (p < 0.001), with higher levels observed in the liver. This study highlights the complex dynamics of plastic additive accumulation in marine predators, providing important insights into how environmental factors and tissue-specific properties influence contaminant bioaccumulation. These findings contribute to a better understanding of plastic pollution and its potential impacts on marine ecosystems.