Narrator: This is Science Today. While many municipalities across the nation have been reusing wastewater without any serious problems, studies of this process are raising concerns. Environmental engineer, David Sedlak of the University of California, Berkeley found this process has led to hormonal changes among certain aquatic life - most notably male fish, which take on female characteristics.
Sedlak: The best evidence that we have suggests that the feminization of fish is related to human hormones. Either natural hormones that are produced in the body or hormones from contraceptives - the birth control pill.
Narrator: Sedlak says the presence of these hormones and trace amounts of pharmaceuticals in wastewater - including antibiotics, ibuprofen and blood thinners - pose new challenges to water reuse projects because many of these compounds are resistant to traditional effluent water treatment techniques.
Sedlak: Many of these compounds pass through sewage treatment plants and so now the questions that we're asking are related to whether these compounds are removed in groundwater.
Narrator: For Science Today, I'm Larissa Branin.