Approaches to Screening for Risk from Pharmaceuticals in Drinking Water and Prioritization for Further Evaluation
The presence of pharmaceuticals in drinking water is not a new issue. In the 1970’s, several researchers reported the presence of clofibric acid, a breakdown product of several blood lipid regulators, and salicylic acid, a breakdown product of aspirin, in waste water. However, as analytical techniques grew more sensitive over the years, many more pharmaceuticals have been detected in ambient water, wastewater, and drinking water.
During 1999-2000, the U.S. Geological Survey carried out the first national survey of the occurrence of pharmaceuticals, hormones, and other chemicals in 139 streams from 30 states. A total of 95 contaminants were targeted, with 80 percent of the streams testing positive for one or more contaminants.
Pharmaceuticals enter water through: flushing unused medications down the toilet or sink; excreting unabsorbed medications into the sewage system; farm animals excreting veterinary drugs into fields where they run off into lakes and streams; and commercial improper disposal methods. Conventional water and wastewater treatment methods allow many pharmaceuticals to pass through unchanged, entering the environment and ultimately the drinking water.
One problem with assessing risk of pharmaceuticals in drinking water is the very large number of pharmaceuticals in use today. Information on the occurrence of pharmaceuticals in drinking water is available only for a limited number of compounds. In addition, many pharmaceuticals are biologically degraded to active metabolites that have not been evaluated. One problem with assessing risk of pharmaceuticals in drinking water is the very large number of pharmaceuticals in use today. Information on the occurrence of pharmaceuticals in drinking water is available only for a limited number of compounds. In addition, many pharmaceuticals are biologically degraded to active metabolites that have not been evaluated.
A number of different approaches have been suggested and published in the peer reviewed literature for screening and prioritizing the hazard posed by low concentrations of pharmaceuticals in drinking water. This white paper summarizes and evaluates a number of risk assessment approaches (including EPA’s current approach), that EPA is aware of, that have been described in the literature. This paper is not a comprehensive compilation of all published approaches. In addition, this paper describes EPA’s current activities and research strategy for pharmaceuticals in water.
