A national survey of U.S. streams across 30 states has revealed a list of compounds that looks like a sample from our national medicine cabinet. Among them are 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.
The study, done by the U.S. Geological Survey, will appear in the March 13 Web edition of the peer-reviewed journal Environmental Science & Technology, published by the American Chemical Society, the world’s largest scientific society.
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 illicit deleterious effects in aquatic species. Effects on humans, if any, have not been determined.
The national reconnaissance survey specifically targeted 95 organic wastewater contaminants. The researchers sampled 139 stream sites throughout the country, 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, says USGS research hydrologist Dana Kolpin, Ph.D., who headed the national study.
In addition to medications, caffeine and cotinine, a nicotine breakdown product, also were among the most frequently detected compounds. So too were cholesterol and coprostanol, steroids that can be indicative of fecal contamination.
Rounding out the list of most frequently detected compounds were the insect repellant DEET, triclosan, the active ingredient in antimicrobial soaps and detergents, a flame retardant (tri(2-chloroethyl) phosphate) and a detergent breakdown product with endocrine disruptive properties (4-nonylphenol).
Of the 95 target compounds, the researchers found 82 of them in at least one stream. And in 35 percent of streams, the scientists found 10 or more compounds. In one stream, they found 38 chemicals. The scientists expected to find most of the compounds, but the prevalence of mixtures was a bit surprising, says Kolpin.
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.
For most of the chemicals, drinking water standards, human health advisory recommendations or criteria to protect aquatic life do not exist. Measured concentrations of compounds that do have 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.
The results of specific site analyses can be found in a USGS Open File Report 02-94, “Water-quality data for pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999-2000”. Available on March 13 at: http://toxics.usgs.gov/regional/emc.html.
The above story is based on materials provided by American Chemical Society. Note: Materials may be edited for content and length.
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