A groundbreaking study conducted by Ifremer reveals the widespread presence of pesticides and pharmaceutical substances along the French coast, even in areas far removed from pollution sources. The analyses, carried out under the Emergent’Sea project between 2021 and 2023, involved over 11,300 samples of seawater and shellfish, from the Baie de Somme to Corsica.
According to the report, 77% of the sought-after substances were detected at least once in seawater, and 65% in shellfish, including oysters and mussels. Each sampled point showed an average of 15 substances in the water and ten in the shellfish, with particularly affected areas where as many as 28 compounds were measured simultaneously.
“All sampled points exhibit contamination,” emphasizes Isabelle Amouroux, head of the Chemical Contamination of Marine Ecosystems (CCEM) unit at Ifremer. “This is the first time a campaign of such scale has been conducted along the entire French coastline. It provides us with a comprehensive view of contamination for over a hundred substances,” she adds.
Scientists even detected traces of contaminants on the small island of Ouessant, off the Breton tip, which had previously been considered relatively unspoiled. On this island, two pharmaceutical substances and fifteen pesticides were measured, demonstrating the ability of these pollutants to disperse far from estuaries and industrialized areas.
This investigation highlights the extent of chemical contamination of French marine ecosystems and raises questions about its potential impacts on wildlife, flora, and seafood consumption.


