Fish are being increasingly exposed to endocrine disrupters

(Image: Pixabay CC0) - When fish ingest microplastics, they often also ingest progesterone. This compound is subsequently released into the digestive tract through chemical reactions with the fish's digestive fluids. That's the key finding of a study carried out jointly by scientists from EPFL, the Swiss Federal Institute of Aquatic Science and Technology (Eawag), Peking University in Beijing, and Oklahoma State University, and appearing in Environmental Science: Processes & Impacts. "Our study shows that microplastics are an additional vector for exposing fish to micropollutants like progesterone, a steroid hormone that can be found in the environment," says Florian Breider, the head of EPFL's Central Environmental Laboratory and a co-author of the study. "These microplastics act like sponges and serve as a vector - they readily absorb hydrophobic micropollutants in water, since the pollutants' molecules would rather attach to the plastic," says Breider. "Once inside a fish, the molecules are released into its digestive tract as a result of the physical and chemical properties of the digestive fluids. Today, nobody knows whether the micropollutants subsequently pass through the intestinal walls and spread to the rest of the fish." - Three kinds of polymers.