Pharmaceutical residues in stranded dolphins in the Bay of Biscay

There is a growing concern about the presence of pharmaceuticals on all trophic levels of the 3 aquatic environment. The presence of pharmaceuticals in the marine environment, which is the 4 final receiver of the continental water including treated wastewater, has been much less 5 investigated than in freshwater. Marine mammals are very suitable sentinel species of the 6 marine environment because they often feed at high trophic levels, have unique fat stores and 7 long lifespan. Small delphinids in particular serve as excellent sentinel species for contamination 8 in the marine environment worldwide. To the best of our knowledge, no pharmaceuticals have 9 been detected or reported in dolphins so far. 10 In the present study, muscle, liver and blubbler samples from four common dolphins (Delphinus 11 delphis) and six striped dolphins (Stenella coeruleoalba) stranded along the Basque Coast were 12 collected. A total of 95 pharmaceuticals based on detectability and predicted ability to 13 bioaccumulate in fish were included in the analysis. 14 At least one pharmaceutical was found in 70% of the individuals. Only three of the 95 monitored 15 pharmaceuticals (orphenadrine, pizotifen, and promethazine) were detected in dolphin ́s tissues 16 (liver or blubber) at very low concentrations (<1ng/g). 17 In this study we also highlight the gap in the knowledge regarding the study organisms and 18 marine environments with respect to pharmaceutical pollution, which demands further 19 research to understand the threat pharmaceuticals might pose for these apex predators.Funding support from Fundación Vital & Ayuntamiento de Vitoria-Gasteiz to GO and the Swedish Research Council Formas 2020-01052 to D.C. and the Basque Government through Consolidated Research Group GIC IT1743-22 to X.L