Since the 1970s, water-quality regulations have focused on a select subset of chemicals deemed representative of humans' impact on the environment. These regulated, so-called "priority pollutants" come from agrochemical and industrial manufacturing pollutants. However, for the past decade, European data have suggested that a wide range of chemicals from consumer activities could trickle through the nation's streams. Still, hydrologists have lacked the analytical tools to measure the low concentrations of these chemicals -- that is, until now.
On Wednesday, the U.S. Geological Survey released a report that shows U.S. waters are awash in trace amounts of pharmaceuticals including contraceptives and antibiotics, as well as cholesterol, insecticides and caffeine that have made it from people through sewage plants to our streams. These substances are largely unregulated and are present at such low levels that they elude the typical biodegradation processes at municipal wastewater treatment plants.
"This is actually the first formal scan across the country of pollutants that result from people's actions and activities," says Christian Daughton, chief of environmental chemistry with the U.S. Environmental Protection Agency in Las Vegas, Nev. The results of the USGS Toxic Substances Hydrology Program (Toxics) study are described in the American Chemical Society's March 15 Environmental Science and Technology.
"We're trying to answer the question 'Do they enter the environment?' So by sampling waters that are very close to source areas, that helps us understand whether they enter the environment, what general levels they're at in the environment and in what combinations," said Herbert Buxton, coordinator of Toxics at a press conference on Wednesday. Researchers surveyed 139 streams in 30 states for a total of 95 organic waste compounds.
The 95 compounds are largely pharmaceuticals and personal care products. The EPA monitors these chemicals during the manufacturing process, Daughton says. But once the products are on the shelves and in the pharmacies, there is no regulation of them as they move from humans into the environment. As a result, these compounds have fallen through the regulatory cracks.
"There's every reason to believe the chemicals have been there all along, we just haven't looked for them and the analytical methods haven't been good enough to get down to the levels that are present," he says. "Now we have evidence that yes, these chemicals are getting into the environment, albeit at very low concentrations."
About 80 percent of the sampled streams contained small amounts of at least one of the 95 compounds measured. In some cases, the study found as many as 38 compounds at a single site. The most frequently found compounds were coprostanol, a naturally occurring steroid that is part of human and animal waste; cholesterol, a plant and animal steroid also naturally occurring; N-N-diethyltoluamide, an insect repellent; and the more-familiar caffeine. Additionally, the survey detected 20 human and veterinary antibiotics, as well as triclosan, the active ingredient in some antibacterial soaps.
Few of the streams contained concentrations of these substances above 1 part per billion -- the maximum allowance for most water-quality standards. "If we consider the 30 most frequently detected of the 95 compounds, only about 5 percent of all those measurements are greater than 1 part per billion," Buxton says. However, he adds, scientific literature has shown that some hormones measure in the study are active at levels even below 1 part per billion, and so it is very important to measure even the lowest concentrations of these compounds.
The Food and Drug Administration (FDA) says it welcomes the study's results. "The FDA will study the results of the U.S. Geological Survey's national reconnaissance survey and if necessary take the appropriate actions to protect public health," said Stephen Sundlof, director of the FDA's Center for Veterinary Medicine, speaking on behalf of the FDA. The New York Times reports that indeed the FDA is considering requiring more testing of the safety of drugs in the environment.
Daughton says there is nothing surprising or alarming about the results, which corroborate past European studies. And he adds that these compounds only represent a larger spectrum of chemicals present in the streams -- a spectrum that could continue to grow as pharmaceutical companies develop more and more drugs with a variety of targets toward specific illnesses. "Now that we know these chemicals, drugs in general, have the potential to get into the environment, it behooves us to pay more attention to what the possible ramifications of those effects could be in the aquatic environment," Daughton says.
Of the 95 compounds, 14 have water-quality standards. "Of about over 1,100 analyses for these compounds that we have some standards for, only about half a dozen actually exceeded the numerical threshold of the standard. Technically speaking, these standards are really not for one time sampling," Buxton says. Therefore, technically, no streams have violated any water-quality standards.
The stream sites chosen were largely located downstream from urban and agricultural areas. Current related research is looking at how these chemicals propagate and affect water sources, and is examining geographic patterns among the stream sites. Buxton says USGS is also working with the Centers for Disease Control and Prevention on antibiotic-resistance studies.
Lisa M. Pinsker
USGS Toxics: Read the study results and related materials.
National Exposure Research Laboratory: Read about the environmental
aspects of pharmaceuticals and personal care products