Per- and polyfluoroalkyl substances (PFAS) are a group of contaminants of emerging concern that have been drawing numerous attention in recent years. Since the 1940s, PFAS have been widely used in industrial and commercial manufacturing processes and products. As a consequence, they are ubiquitous in our environment nowadays. PFAS are called "forever chemicals" because their molecules are very stable and resistant to decomposition, making them highly persistent in the environment to travel long distances through air and water. PFAS can be absorbed by marine organisms, entering the marine food chain via accumulating in various microalgae, zooplankton, and fish, potentially impacting marine ecosystems. In addition, consuming seafood is a primary pathway of human exposure to PFAS. However, current knowledge of the interactions between PFAS and marine organisms is still very limited, and available data is not comprehensive. Research is needed to understand the factors controlling PFAS accumulation in marine organisms and their transfer through the marine food chain.

In collaboration with teams from Stony Brook University, Beneath the Waves, and Cape Eleuthera Institute, muscle tissue samples from various shark species were collected from the New York Bight (NYB) and the waters of the Bahamas Archipelago. We exerted a precise analytical method to measure 40 PFAS. This study is the first to report on PFAS in multiple shark species along the northwest Atlantic coast. It also compares how human activities influence PFAS in sharks within these two distinct marine ecosystems.

Sharks are meso-to-apex predators in marine food webs. With their long lifespans and slow growth, they tend to accumulate various pollutants in their bodies, making them a suitable sentinel species for monitoring the health of marine ecosystems. This study acknowledges the importance of sharks to marine ecosystems. Therefore, sharks were captured and secured alongside the vessel. Their physiological parameters were measured, and muscle tissue samples were obtained through biopsies using a customized melon baller. Finally, the sharks were safely released back into the sea. The entire sampling process was conducted without sacrificing any sharks.

Our results indicate that sharks off the coast of New York exhibited a greater diversity of PFAS (15 PFAS detected) and had total PFAS concentrations five times higher than those found in samples from the Bahamas. This reflects the great impact of anthropogenic contaminants on coastal ecosystems adjacent to a dense and populated metropolitan area. The accumulation of PFAS in sharks was primarily from water and dietary intake, with the contribution of each exposure pathway potentially varying in response to the carbon chain length of PFAS compounds. There was no significant correlation between PFAS concentrations and the sharks' length or gender. However, ultra-long-chain PFAS (carbon chain C ≥ 10) showed significant positive correlations with stable nitrogen isotopes (δ¹⁵N) and total mercury only in some shark species. This suggests that although PFAS can accumulate in marine organisms, their accumulation mechanisms and patterns differ from those of traditionally studied bioaccumulative pollutants. Applying our data for perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) to the PFAS tolerable weekly intake established by the European Food Safety Authority, the results showed that over 84% of the shark muscle tissue samples exceeded the threshold value. Our study provides a dataset of PFAS in diverse sharks from the coastal Northwest Atlantic Ocean, serving as a baseline for policy-making against PFAS contamination in these two critical marine ecosystems and seafood safety for human exposure.