Pharmaceuticals, including birth-control hormones and anti-seizure medications, have been found in Lake Michigan and public water supplies, according to a new study. The study was jointly sponsored by the U.S. Fish and Wildlife Service and the American Pharmacists Association.

The water system examined serves more than a quarter-million people in Grand Rapids, East Grand Rapids, Walker, part of Kentwood, Ada, Cascade and Grand Rapids townships, as well as parts of Ottawa County.

In Lake Michigan, near the Grand Rapids water filtration plant, tests found traces of Tylenol, ibuprofen, hormones from birth-control pills, and some beta blockers in heart medication, Department of Environmental Quality toxicologist Amy Perbeck stated.

In treated water at the Grand Rapids water filtration plant, scientists found traces of the anti-seizure medication carbamazepine, she said. The drugs were measured in parts per trillion -- too small to be considered a "therapeutic dose" in humans, said Perbeck.

"Someone would have to drink 17,000 gallons of water to get the concentration they would get in one ibuprofen pill," she said.

However, Perbeck expressed concern about the effect of birth-control hormones on fish, stating "The fish are constantly exposed to hormones." In some parts of the country, scientists have found male fish with female ovarian tissues.

Professor Rick Rediske, senior program manager at Grand Valley State University's Annis Water Resources Institute, pointed out even the smallest amounts of pharmaceuticals, as well as substances such as anti-bacterial soap, could harm aquatic life.

He referred to shellfish, which excrete serotonin to signal they are ready to mate. Trace amounts of serotonin in anti-depressants such as Prozac could send false messages.

"It can mess up part of their life cycle," he said, "It's very complicated when there are very low levels of exposure over a long time."

While some scientists claim the drugs are too diluted to harm humans, they acknowledge no one knows the dangers of lifetime exposure.

"Pharmaceuticals are toxic chemicals that pollute the environment, and the pharmaceutical industry has so far refused to take responsibility for the environmental impact of its products," explained Mike Adams, author of The Real Safety Guide to Protecting Your Environment, "Consumers need to be warned that popping pills is not just harmful to your own health; it's also harmful to the health of water supplies and aquatic systems."