title: Pharmaceutical residues in the drinking water supply: modeling residue concentrations in surface waters of drugs prescribed in the United States.
abstract: BACKGROUND
  Pharmaceutical residues and other organic wastewater contaminants (OWC) have been shown to survive conventional water-treatment processes and persist in potable water supplies.
  
  
  OBJECTIVE
  To estimate the geographical distribution of the Predicted Environmental Concentration (PEC) of selected drugs prescribed by office based physicians in the United States (US), after non-metabolized residues have been excreted and processed in wastewater treatment plants.
  
  
  METHODS
  The geographical distribution of the PEC in surface waters of pharmaceutical residues was calculated, in four regions of the US. Prescription drug data was obtained from the National Ambulatory Medical Care Survey (NAMCS). The PEC of three drugs prescribed by office based physicians in the US between 1998 and 2000 was compared to the concentrations of these pharmaceuticals found in a surface water characterization project conducted by the United States Geological Survey between 1999 and 2000.
  
  
  RESULTS
  There were 803,185,420 medications prescribed by office-based physicians in the US between 1998 and 2000. Relief of pain, hormonal, cardiovascular and antimicrobial medications followed very similar prescription patterns, both in terms of quantity and geographical distribution. Together these four types of medications account for more than half of the medications prescribed between 1998 and 2000. The concentration of pharmaceutical residues found in the drinking water supply was not significantly correlated to the PEC of pharmaceuticals prescribed by office-based physicians.
  
  
  CONCLUSIONS
  The geographical distribution of medications prescribed by office based physicians in the US underlines the need to implement effective public health strategies.
authors.affiliation: Department of Epidemiology, Mailman School of Public Health, Columbia University, USA. rguerre3@jhmi.edu
authors.forename: Rafael
authors.initials: R
authors.lastname: Guerrero-Preston
authors.forename: Paul
authors.initials: P
authors.lastname: Brandt-Rauf
mesh_terms: D004350:Drug Residues / Q000032:analysis*; D055553:Prescription Drugs / Q000032:analysis*; D014481:United States; D014873:Water Pollutants / Q000032:analysis*; D014881:Water Supply
chemical_list: D055553:Prescription Drugs; D014873:Water Pollutants