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What's in the water?

Better detection tools reveal possible ecological 'villains' – from hormones to fire retardants – in US streams and rivers

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Moreover, European farming practices, antiquated and ill-maintained sewer systems, (particularly in the former East bloc), and the flow characteristics of many European rivers raised the likelihood that drugs were finding their way back into drinking water.

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Daughton notes, for example, that following the fall of the East bloc in the early 1990s, scientists found evidence of drugs in the former East Berlin's tap water.

The research in Europe and rising concerns among public-health researchers and officials in the US triggered the USGS study, says Buxton, who coordinates the toxic-substances hydrology program at the USGS office in Trenton, N.J.

Troubling presence of antibiotics

To ecologist Rebecca Goldburg, the most troubling set of ingredients is antibiotics, particularly down on the farm.

"The use of antibiotics in agriculture is growing," notes Dr. Goldburg, senior scientist with Environmental Defense, a New York-based group. Of particular concern, she says, are those fed each year to hogs, chickens, and cattle to promote growth.

By some estimates, these "subtherapeutic" doses constitute 8,000 tons of antibiotics a year.

The concerns arise over the prospect that over time, the bacteria these antibiotics are designed to destroy will grow increasingly resistant to the compounds and at a faster pace than would be the case if the antibiotics were used only to treat animals diagnosed with disease.

In addition, over the years antibacterial agents have become common in soaps and other personal-care products, which wind up being rinsed down the sink and into the sewer system.

For his part, the EPA's Daughton is focusing his research on the effects pharmaceuticals may have on aquatic environments.

"Drugs are designed for people, so not much has been done to test them on aquatic organisms," he says.

Thus, he continues, the presence of drugs in rivers, lakes, and streams may have a more serious effect on fish, shellfish, and other organisms they rely on for food than on humans. The problem is that little is known about the impact of drugs on aquatic ecosystems.

Research in this area could become more important as drug companies develop new, more potent compounds. Daughton notes that the drug companies are intensely interested in results coming out of the federal Human Genome Project.

That project aims by the end of next year to complete its goals of identifying all of the estimated 30,000 genes in human DNA, and determining the sequence of four basic chemical building blocks that DNA is built upon.

Drug companies, he says, hope to use data from the project to develop new, more potent compounds for battling a range of diseases -- compounds that, if history is any indication, also could wind up in waterways.

Already, he notes, studies have shown that antidepressants can trigger premature spawning in shellfish, while other compounds used to treat heart conditions have blocked the ability of fish to repair damaged fins.

The canary in the mine

Even less well-known are the effects these and other compounds might have in combination, he says.

Some pharmaceuticals include compounds also found in pesticides, according to Marsha Black, an aquatic toxicologist at the University of Georgia at Athens.

Armed with a $500,000 grant from the EPA, she is heading a team that will be looking for five commonly prescribed antidepressants in samples taken from wastewater treatment plants.

Already, Dr. Black has documented one antidepressant's lethal effects on sand fleas. While most people might not mind fewer of these tiny crustaceans nipping at them, these creatures, like canaries in a coal mine, provide researchers with valuable clues about the quality of surface waters, she says.

Not your average contaminants

Using new technology, scientists are finding chemicals in US rivers, streams, and lakes that have gone undetected for years.

These "emerging contaminants" include:

• Steroids.

• Nonprescription drugs.

• Insect repellent.

• Detergent byproducts.

• Disinfectants.

• Plasticizers.

• Fire retardants.

• Antibiotics.

• Insecticides.

• Reproductive hormones.

• Other prescription drugs.

• Antioxidants.

• Fragrances.

• Solvent.