Studies reveal disturbing findings on contaminants
Steroids, insect repellent, caffeine, triclosan and other organic chemicals found in surface waters are in low concentrations, but the combination of these substances may increase their toxicity.
By Pamela Wolfe
Recent studies in Europe and the United States on pharmaceuticals, hormones and other organic chemicals in groundwater and surface waters reveal disturbing findings downstream of metropolitan and industrial areas, including livestock farms, and less developed areas. More research is necessary, but well-documented statistics clearly indicate the troubling widespread presence of these substances flowing in rivers, streams and aquifers even after passing through wastewater treatment facilities.
Little is known about potential effects of these emerging contaminants on human and aquatic ecosystems. Most wastewater and sewage treatment plants are not designed to remove these contaminants.
On 13 March, the US Geological Survey (USGS) revealed that its first nationwide study of emerging contaminants - pharmaceuticals, hormones and other organic wastewater-related chemicals - detected low concentrations of these substances in 80% of the 139 streams in 30 US states during 1999 and 2000. Drinking water standards or health advisories do not even exist for 85 of the 95 chemicals examined in the study. The USGS used five new analytical methods that can detect the presence of 20 to 30 contaminants in one analysis.
Chemicals used in households, agriculture and industry flow into water bodies through many wastewater sources. According to Dana Kolpin, a USGS hydrologist and head of the study, those compounds include human and veterinary drugs, including antibiotics, natural and synthetic hormones, detergents, plasticisers, insecticides and fire retardants. The most frequently detected compounds include coprostanol (fecal steroid), cholesterol (plant and animal steroid), N-N-diethyltoluamide (insect repellent), caffeine, triclosan (antimicrobial disinfectant) and 4-nonylphenol (detergent metabolite).
Kolpin reported: "Steroids, non-prescription drugs and a chemical found in insect repellents were the chemical groups most frequently detected. Detergent metabolites, steroids and plasticisers were generally measured at higher concentrations than the other chemical groups, but concentrations measured in this study generally were very low (less than 1 part per billion)."
In the UK, the Environment Agency released evidence in late March that demonstrated the effects of less than one nanogram per litre of a synthetic hormone used in the contraceptive pill 17alpha-ethinyl oestradiol on the declining ability of two native UK species of fish to reproduce. The long-term effects on human reproductive health can only be determined by more extensive studies.
Contaminants when combined may increase in potency, according to new research conducted at the University of London. Toxicologist Andreas Kortenkamp and colleagues found that a combination of eight estrogenic chemicals created a biological response in yeast cells, although each chemical alone did not trigger a response. Given these findings, what are the combined potencies of estrogenic chemicals that pass through sewerage systems, treatment plants and then water resources? Do these substances degrade or do they slowly increase in concentration? Is there a causal connection to human infertility problems or increased incidence of cancer?
Antibiotics from human and livestock sources are a serious concern. Low levels of antibiotics in water resources can lead to the development of antibiotic-resistant bacteria, new bacteria that may not be controlled by available medicines.
Scientists in Europe began studying the presence of pharmaceuticals and other substances in the water environment years in the early 1990s, earlier than US researchers. Studies conducted by Thomas A. Ternes, a chemist at the Institute for Water Research and Water Technology in Wiesbaden, Germany, confirm that activated carbon and ozone, commonly used in Europe to disinfect drinking water and not sewage effluent, can remove many drugs from sewage. The cost of using these disinfection agents in sewage plants is high. Ternes is now working on new treatment techniques to remove pharmaceuticals from drinking water and wastewater.
Looking ahead, more research on the long-term effects of emerging contaminants on human health must be carried out before municipalities and water companies will invest in new sewage treatment processes. Common sense, however, does suggest that the wide variety of pharmaceuticals and household chemicals that are flushed down domestic drains or the antibiotics, pesticides and hormones that run off from livestock farms into water resources do not magically disappear. The USGS study reveals their troubling presence in full detail.
Pamela Wolfe, Managing Editor