Studies conducted by a Canadian scientist in 2002 show that white perch caught for research had male and female sex organs, and a second study showed that male snapping turtles had traces of estrogen. Scientist Chris Metcalfe, of Trent University in Peterborough, Ontario, said suspicions are that the feminization of wildlife is linked to chemicals coming from sewage plants.

These chemicals can affect sperm quality, which can affect reproduction.

The estrogen shows up in water either through waste or through birth control pills flushed down toilets or sinks. Chemicals that mimic the effects of estrogen include atrazine, a herbicide washed off farmlands and into lakes and rivers.

"Atrazine actually affects the sexual development of organisms," said Oakland University professor Linda Schweitzer, a professor of environmental chemistry at Oakland University who is studying the issue.

"Atrazine stimulates the enzyme aromatase, which induces the male hormone testosterone to become a form of the female hormone estrogen, and that feminizes fish, frogs and possibly other organisms."

Schweitzer said she does not know how the chemical affects humans. But the Environmental Protection Agency has found that atrazine can cause heart congestion, muscle spasms and possibly cancer.

Traces of estrogen and atrazine also are showing up in intakes at drinking water plants that draw their water from rivers and lakes containing the chemicals. Schweitzer has found traces of both in plants in Detroit and Windsor.

Detroit water officials say the drinking water supply is safe.

The atrazine -- found in low concentrations of between 10 and 20 parts per trillion -- was "found in raw water entering the plant, but not in water after it was treated," said Pamela Turner, assistant director of water operations for the Detroit Water and Sewerage Department.

Scientists from across the globe are also concerned about the gender-bending chemicals. More than 100 scientists from 15 countries in Europe signed a report in June raising concerns about what it called the "high prevalence" of reproductive disorders in European males, genital malformations and low sperm counts. They called for a reduction of chemicals being released into waterways from sewage treatment plants and urged an acceleration of research.

At the same time, the Journal of the American Medical Association noted in a July 20 article that there is "accumulating evidence" that the wide use of chemicals may have a hormonal effect on the body and long-term health risks. It said 80,000 chemicals are used commercially in the United States.

Some of the potentially harmful chemicals come from prescription medicine that is flushed down the toilet or bathroom sink, said Thomas Kalkofen, director of the Macomb County Health Department.

The health department started a program earlier this year to collect outdated or unused medication so it wouldn't end up in the waste stream. As of July, 151 pounds had been disposed of.

Lucy Doroshko, recycling specialist with the Michigan Department of Environment Quality, said some communities also accept drugs under hazardous household waste collection programs.

"Do not flush it down the toilet or sink," Doroshko said.