What's in the water?

From its headwaters at Echo Lake in Hopkinton, Mass., the Charles River glides past yards, saturates wetlands, and slips under highways before emptying into Boston Harbor.

Over the years, this 80-mile odyssey through 23 cities and towns has left what seemed to be a faint imprint on the Charles's tea-colored water. But advances in the ability to detect pollutants are giving scientists a clearer idea of the nature of that imprint – and is also triggering interest in research on whether these pose a threat to the environment and to humans.

The chemicals range from fire retardants and detergent byproducts to prescription drugs, antibiotics, and hormones.

Known as organic-waste contaminants, these compounds pass through sewage-treatment plants virtually untreated. They represent the vanguard of what researchers have dubbed emerging contaminants: chemicals whose presence in US rivers, streams, and lakes has gone undetected for years and whose effects – singly and in combination – on fish, aquatic plants, and humans often are poorly understood.

Last week, the United States Geological Survey (USGS) released its first survey of organic-waste contaminants in US surface waters, and the Charles River has plenty of company. Researchers found organic-waste contaminants in 80 percent of the 139 streams and rivers that were tested in 30 states.

During the course of the survey, which ran from 1999 through 2000, the researchers found 82 compounds out of the 95 they sought.

The researchers acknowledge that the sites were selected because they presented a high likelihood that the contaminants would be found. The survey was as much a test of new sampling technologies as it was an exercise in environmental monitoring. But the target compounds also were selected because several are beginning to appear in scientific journals as potential ecological villains.

According to Herbert Buxton, a USGS scientist who took part in the survey, "Thirty-three compounds are known or suspected to be hormonally active." These chemicals, which include steroids, can affect the growth and development of aquatic life.

Dr. Buxton and his colleagues note that the compounds they found appeared in concentrations that rarely violated drinking-water or aquatic-life standards.

But, he adds, many of the compounds have no such guidelines. Moreover, samples exhibited chemical stews of up to 38 contaminants, and little is known about how these interact, he says.

"We shouldn't confuse the ability to measure these concentrations with whether or not they're harmful," Buxton cautions, noting that these are two separate issues.

However, he adds, the ability to measure organic waste contaminants in ever weaker concentrations allows researchers to focus on questions of risk early.

Compared with other parts of the world, the United States is a late bloomer on the issue of these emerging organic wastewater contaminants, particularly pharmaceuticals and antibiotics, according to Christian Daughton, who heads the environmental chemistry branch at the Environmental Protection Agency's National Exposures Research Laboratory in Las Vegas, Nev.

The sources for these compounds vary. Hormones and antibiotics in animal feed appear in waste and can leach into local streams and rivers. Drugs and antibiotics designed for humans move through sewage systems.

Tossed into the trash, such leftovers also are often carted off to landfills, where seeping rainwater can dissolve the capsules and carry away the compounds they contain.

EPA chemist Wayne Garrison was the first to identify drugs in sewage, in the mid-1970s. His chemo-sleuthing turned up evidence of caffeine, aspirin, and nicotine. "It was noted, then people shrugged and moved on," Dr. Daughton says.

The issue lay dormant until the 1990s, when the Europeans tested samples from their waterways and found evidence for a range of human and agricultural pharmaceuticals.

"The Europeans have a higher density of urban life around surface waters" than does the US, Daughton says in explaining why European researchers were quicker to focus environmental research on human and animal drugs in their waterways.

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