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20 years after fatal outbreak, Milwaukee leads on water testing
Beginning in 2004, Milwaukee Water Works launched an aggressive program to monitor for a new potential public health threat: the largely unregulated group of chemicals known as “emerging contaminants,” including estrogen and testosterone, flame retardants, pesticides, explosives and pharmaceuticals.

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endocrine disruptors in the environment.

Researchers at the University of Wisconsin-Milwaukee have found that low doses of a chemical mixture of an herbicide and a plasticizer can lower testosterone levels in fathead minnows.

Testosterone plays a key role in male human health, regulating everything from the development of reproductive tissue to the building of bone and muscle.

The researchers exposed the fish to a blend of linuron, an herbicide used to control grasses and weeds, and DEHP, a plasticizer used to make medical products.

The chemicals are each known as potent disruptors of testosterone at high levels. But less is known about the effects of low doses and mixtures of chemicals, which is how humans and wildlife are usually exposed.

Fathead minnows are common in Wisconsin’s waters, and are sold in bait shops. They’re also an important species for research on toxic substances.

“Fish provide a good model for human biology,” said Rebecca Klaper, an ecologist with the UW-Milwaukee’s School of Freshwater Sciences who coauthored the study. “They can help us test what might happen when humans come in contact with a compound.”

The nonprofit Wisconsin Center for Investigative Journalism ( collaborates with Wisconsin Public Radio, Wisconsin Public Television, other news media and the UW-Madison School of Journalism and Mass Communication. All works created, published, posted or disseminated by the Center do not necessarily reflect the views or opinions of UW-Madison or any of its affiliates.

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