“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.”

“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.”

The study looked at three types of polymers commonly found in Swiss lakes and streams: polyethylene, polypropylene and polystyrene. The researchers examined how well the polymers absorbed micropollutants such as progesterone and how quickly they in turn could be released in a fish’s digestive tract.