The chemicals go down the drain, but in the environment they remain. Researchers have found that a complex brew of everyday compounds -- from products as ubiquitous as shampoo, bug spray and even that morning cup of coffee -- lingers in Minnesota waters even after they're showered off or dumped down the sink.

Those persistent chemicals include caffeine, synthetic musk used in personal-care products, a flame retardant, a herbicide, insect repellent and several medications, according to the most extensive study ever conducted of the state's waters.

Little is known about the risk of these compounds, especially at the low levels detected. But 13 of them are known to disrupt the hormones and sexual development of some fish or other animals, according to the study by three government agencies.

"Because they are a constant source, everyday aquatic organisms are bathed in these compounds, and I don't think anybody knows how that affects them," said Kathy Lee, a hydrologist for the United States Geological Survey and chief author of the study.

Scientists from the USGS, the Minnesota Department of Health and the state Pollution Control Agency found 74 chemicals at 65 sites across the state from late 2000 to 2002. The samples came from rivers and streams near municipal water supplies and sewage treatment plants, treated drinking water and water below landfills and livestock lagoons. The study did not attempt to identify the chemicals' sources.

The study, which cost $564,000, was presented at a conference here last month.

Many chemicals were found just downstream of sewage treatment plants at East Grand Forks, Rochester, Duluth and St. Paul.

At the main Twin Cities metro area plant in St. Paul, about 200 million gallons of wastewater are treated and released into the Mississippi River daily.

The treatment plants remove metals and several pollutants, but not many of the hormones, pharmaceuticals and other chemicals flushed from toilets or rinsed down drains.

"We're not designed to remove these chemicals," said Rebecca Flood, environmental manager for the plant.

Detecting those compounds at such low levels -- often in the parts per billion -- is cutting-edge research, Flood said.

Traces of some chemicals also were found in the intakes of municipal water-treatment plants at Moorhead, East Grand Forks, St. Cloud, Mankato, St. Paul and Minneapolis. But water after treatment at those plants showed either no contaminants or barely detectable levels, said Doug Mandy, manager of the drinking water protection section for the Health Department.

"From a health standpoint, we're fairly certain that this is not a problem at the levels that we found," Mandy said. "But our concern is that these numbers will continue to grow over time because people will continue to use these items or products and they will continue to enter the environment."

Drugs with sexual side effects eventually could become a problem for drinking water quality downstream, and antibiotics in the water may result in strains of bacteria that become resistant to antibiotic treatment, said Leroy Folmar, a retired research physiologist for the federal Environmental Protection Agency.

"When you are prescribed medication of some kind, it is usually way more than your body requires, so it is excreted and much of the drug or chemical ends up in the sewage treatment plant," Folmar said.

Another major concern is the effect of natural and synthetic hormones, or chemicals that mimic hormones, on aquatic creatures.

In the mid-1990s, Folmar found that male fish in the Mississippi just below the metro sewage treatment plant were becoming "feminized." Male fish had depressed levels of testosterone and were producing a yolk protein normally made only by female fish. Female walleye near the plant had five times the normal levels of estrogen in their blood compared with those taken elsewhere.

A pair of synthetic musks detected frequently in the study are used to mask scents or add fragrance to shampoos, perfumes and household cleaners. Keri Hornbuckle, a professor of civil and environmental engineering at the University of Iowa, said at least a million pounds of these chemicals are used in the United States each year.

"You'd be hard-put to find someone who doesn't use these chemicals in some personal care product," Hornbuckle said. "It's amazing that we're releasing such large quantities of them every day, yet we have almost no information about their potential costs to the environment."

Source: Associated Press