Drugs, Chemicals Pollute U.S. Waterways
By Cat Lazaroff
WASHINGTON, DC, March 13, 2002 (ENS) - Waterways across the United States are contaminated by a medicine chest of antibiotics, hormones, caffeine, painkillers and other drugs, finds the first nationwide study of pharmaceutical pollution in the nation's rivers and streams. Though the report is intended as a baseline for future research, funding cuts could threaten the future of such studies.
The survey, performed by the U.S. Geological Survey (USGS) revealed a list of compounds including the painkillers acetaminophen and ibuprofen, prescription medicines for cardiac disorders and hypertension, and female sex hormones used in birth control pills and hormone replacement therapy.
Although concentrations of most of the compounds were low, typically much less than one part per billion, previous research has shown that exposure to levels even lower than reported in this survey can cause harm to aquatic species. Effects on humans, if any, have not been determined.
"Little is known about the environmental occurrence of many chemicals we use to maintain and improve the quality of our daily lives," said Dr. Robert Hirsch, USGS associate director for water. "This study begins a process of exploring the occurrence of these chemicals in our nation's streams. The new techniques for measuring these chemicals will be very helpful for the many scientists who study contaminant movement, impacts on ecosystems, and human health effects."
The national reconnaissance survey targeted 95 organic wastewater contaminants, and includes samples collected at 139 stream sites in 30 states during 1999-2000.
The 95 chemicals were picked on the basis of estimates about the quantities used, toxicity, potential hormone activity, suspected persistence in the environment and the availability of reference standards and an analytical method, said USGS research hydrologist Dana Kolpin, PhD, who headed the national study.
The USGS study suggests that chemicals used in households, agriculture, and industry can enter the environment through a variety of wastewater sources, according to Kolpin. Those compounds include human and veterinary drugs, including antibiotics, natural and synthetic hormones, detergents, plasticizers, insecticides and fire retardants.
The most frequently detected compounds included:
"Overall, steroids, non-prescription drugs and a chemical found in insect repellents were the chemical groups most frequently detected," Kolpin said. "Detergent metabolites, steroids and plasticizers were generally measured at higher concentrations than the other chemical groups, but concentrations measured in this study generally were very low - less than one part per billion."
Of the 95 target compounds, the researchers found 82 of them together in at least one stream. In 35 percent of streams tested, the scientists found 10 or more compounds, and in one case, 38 chemicals were present in a single water sample.
The scientists expected to find most of the compounds, but the prevalence of mixtures was a bit surprising, Kolpin said.
Since this was the first attempt to survey most of these compounds the researchers tried to pick streams most likely to show some contamination. Most are downstream from wastewater treatment plants or intense livestock activity. Only a few are from less developed, more pristine areas.
The reconnaissance study is intended to set a baseline for future research to examine questions such as how far downstream from their sources these chemicals may be found, or how concentrations of these chemicals vary with climate, land use, stream flow rates, or waste characteristics and treatment methods.
For most of the chemicals - 81 out of 95 - drinking water standards, human health advisory recommendations or criteria to protect aquatic life do not exist. Measured concentrations of compounds that do have such standards rarely exceeded them.
When toxicity is taken into account, the measured concentrations of reproductive hormones may have implications for the health of aquatic organisms, according to Kolpin and his colleagues.
However, limited information is available on the potential health effects to human and aquatic ecosystems from low level, long term exposure or exposure to combinations of these chemicals. For example, the researchers found contamination by 14 antibiotics used in human medicine and animal agriculture.
"This is important new data," said Dr. Tamar Barlam, an infectious disease specialist at the Center for Science in the Public Interest. "We know that bacteria are more likely to become resistant to drugs the more they encounter antibiotics. The next step is to see if there is a connection with contamination of our waterways and antibiotic resistant infections in people."
Some of the antibiotics given to farm animals are excreted in feces or urine, and can reach waterways from leaking waste lagoons or when wastes are spread as fertilizer onto agricultural fields.
"The USGS study shows that many antibiotics are moving through our environment in ways that weren't widely appreciated before," noted Dr. Mardi Mellon, senior scientist at the Union of Concerned Scientists (UCS).
The USGS researchers suggest that their study, funded by the USGS Toxic Substances Hydrology Program, can guide future research in these areas. However, the Bush administration's proposed 2003 budget eliminates all funding for this program - the only one of its kind in the nation.
"Continuing this USGS program is critical for public health, but the President's proposed budget would eliminate it," said Rebecca Goldburg, PhD, senior scientist at the conservation group Environmental Defense. "The USGS now has a combination of expertise and experience conducting these kinds of studies found nowhere else. If funding is abolished, the USGS' unique ability to perform these important studies will be lost."
The study, "Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000: A national reconnaissance," appears today in the Web edition of the journal "Environmental Science & Technology," published by the American Chemical Society at: http://pubs.acs.org/journals/esthag/index.html. The study is also available at: http://toxics.usgs.gov/regional/emc.html
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