Drugs and other chemicals found in US watercourses

The chemical compounds included human and veterinary drugs, such as antibiotics, natural and synthetic hormones, detergents, plasticizers, insecticides and fire retardants, according to Dana Kolpin, a USGS research hydrologist and head of the study. The research is published in the journal, Environmental Science & Technology, and reveals that traces of chemicals have been detected at very low concentrations in streams across the U.S. “Overall, steroids, non-prescription drugs and a chemical found in insect repellents were the chemical groups most frequently detected,” Koplin said.

The study was conducted during 1999 and 2000, across a network of streams in 30 states. The streams drain watersheds of varied climate, geology, land use and size. Most water sampling sites were located downstream of areas of intense urbanisation and livestock activity, and where wastewater was known or suspected to enter the streams.

“We had developed new testing methods and we were pleased to be able to accurately detect such low concentrations of chemical compounds,” a spokesperson for USGS told edie.

The most frequently detected compounds included: coprostanol, a fecal steroid; cholesterol, a plant and animal steroid; N-N-diethyltoluamide, an insect repellant; caffeine; tricolsan, an antimicrobial disinfectant; tri (2-chloroethyl); phosphate, found in fire retardants; and 4-nonylphenol, a detergent metabolite.

Traces of chemicals for which standards or criteria do exist, were found rarely to exceed these. However, 81 of the 95 chemicals examined have no drinking-water standards or any health advisories. The potential effects of their presence in the water system therefore remain unknown.

Furthermore, in half of the streams tested, seven or more compounds were detected, and in one stream, an alarming 38 chemicals were present in a single water sample.

As the possible effects of many of these chemicals are currently unknown on an individual basis, it is impossible to predict what the effects of a cocktail of chemicals might be.

“This study focused on surface water rather than drinking water from the tap,” Kinerney explained. “The next step will be to examine what happens to these chemicals when they combine with chlorine and fluoride”.

The detectable quantities of chemicals also imply that chemical compounds survive current wastewater treatment and biodegradation, and this aspect too will need to be the focus of future research.

In 1997, the number of drugs for which environmental assessments were required was greatly reduced in an effort to streamline regulations. Some drugs that are natural substances including hormones like estrogen, were excluded from such assessments. Studies have shown that estrogens in particular can alter hormone levels and the sexual characteristics in fish and other aquatic species.

“We need to know where these chemicals end up,” Kinerney concluded. “Do they settle as sediment, travel great distances, or end up in fish tissues? There’s so many questions”.

In the light of the findings of the USGS, The Food and Drink Administration (FDA) is now considering requiring more tests for the possible effects of drugs on the environment, according to a report in the New York Times. “We’re looking very carefully into this data and aren’t ruling not the fact that we may have to make changes” said Dr Steven K. Galson, deputy director of the FDA Centre for Drug Evaluation and Research.