The millions of doses of prescription drugs that Americans swallow annually to combat cancer, pain, depression and other ailments do not disappear harmlessly into their digestive systems, researchers have determined, but instead make their way back into the environment where they may contaminate drinking water and pose a threat to aquatic wildlife.
With this in mind, environmental engineers at Johns Hopkins have launched an ambitious research program aimed at identifying the scope of the nation's prescription drug pollution problems. The researchers recently received a three-year $525,000 U.S. Environmental Protection Agency grant to study pharmaceuticals and antiseptics in drinking water, sewage treatment plants and coastal waters.
During an April 10 session at the 223rd national meeting of the American Chemical Society, held in Orlando, Fla., members of the Hopkins team unveiled two new scientific tools to aid in the investigation of prescription drug pollution. One is a survey of the estimated environmental concentration of the 200 drugs that are prescribed and sold most often. The other is a new, highly sensitive lab test that can detect a minute amount of several prescription drugs in water samples.
Being able to track these drugs is important because many prescription medicines consumed by Americans are not rendered biologically harmless when they pass through the body, the Hopkins researchers say. Conventional sewage treatment systems may not remove them, and unused drugs may be flushed down the toilet or thrown into the trash, ultimately ending up in groundwater or surface water, where they may affect aquatic life and drinking water quality.
"This is an important new research area," says A. Lynn Roberts, who heads the Johns Hopkins team. "Over the past few years, scientists in Europe have found pharmaceuticals in natural waterways, sewage treatment effluents and even in drinking water. Yet until this year there have been virtually no scientific studies examining this issue in the United States. It's important that we begin to look at this because there are many ways in which pharmaceuticals in the environment could produce undesirable effects on aquatic organisms or even humans."
As an example, Roberts, an associate professor in the Whiting School of Engineering's Department of Geography and Environmental Engineering, pointed out that popular anti-depressants work by altering levels of a neurotransmitter called serotonin. But serotonin also causes many aquatic creatures to spawn. As a result, pharmaceuticals in the wild could upset natural breeding cycles. In humans, pregnant women are warned not to consume medications that could harm their developing fetus. But what if small amounts of these drugs are present in drinking water?
"Pharmaceuticals have high biological activity," Roberts says. "We may be able to tolerate them for a short period of time, but that doesn't mean they won't hurt us--or developing fetuses or aquatic organisms--at higher concentrations or over a long period of time."
At the American Chemical Society meeting, two members of Roberts' team made public some early steps in the effort to determine which pharmaceuticals are escaping into the environment and how much is present.
Padma Venkatraman, a postdoctoral fellow, presented estimates of probable environmental concentrations of the 200 most frequently sold and prescribed drugs. She has concluded that anti-depressants, anti-convulsants, anti-cancer drugs and anti-microbials are among the pharmaceuticals most likely to be found at "toxicologically significant levels" in the environment. "We're trying to make an intelligent guess as to what's out there in the environment and what's probably toxic," Venkatraman says. "We certainly don't have any evidence that most pharmaceuticals pose a human health risk."
Also at the meeting, Michael L. Blumenfeld, an undergraduate, presented a new method of detecting tiny amounts of several drugs in natural waters, using a lab technique called gas chromatography/mass spectrometry. The test is so sensitive it can detect a gram of pharmaceutical in more than 1 billion liters of water. Blumenfeld's test, developed in collaboration with Roberts and Venkatraman, will allow researchers in academic labs to test for the presence of particular drugs that may pose a problem in the environment. Blumenfeld, a senior majoring in chemistry, received financial support through a Provost's Undergraduate Research Award.
As the project continues, Hopkins researchers plan to test water before and after it emerges from drinking water treatment plants to determine how effectively pharmaceuticals are being removed. Team members also will conduct tests to see how well pharmaceuticals are being removed at sewage treatment plants in Massachusetts and Maryland. In the environmentally sensitive upper Chesapeake Bay, they will check for the presence and concentration of drugs and antiseptics. The researchers will try to determine how efficiently nature's self-cleansing processes eliminate these man-made pollutants.
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