Anti-androgenic chemicals found in wastewater are turning male fish into females, suggests a new study on UK rivers. Chemicals spread in wastewater can block the action of certain hormones, leading to the feminisation of reproductive organs in male fish. As a result, the reproductive capacity and population levels of certain species has been hit, especially in urban areas where residues from hormone therapies and pills are ending up in wastewater. The study also suggests that there may be a link between chemicals in waste and human fertility.