In 1999, CHEEC and the Iowa District of the United States Geological Survey (USGS) joined in a collaboratively funded project investigating the presence of antibiotics/antimicrobials in Iowa surface waters. The study objectives are to provide baseline data for types of antimicrobial compounds present, concentrations, and geographical distribution. Thirty sites from across the state were selected representing a cross section of large and small watersheds and stream flows. Of secondary importance of this study was for laboratory methods development for detection of these compounds. Thirty-one sites from across the state were sampled, representing large and small stream flows. Streams were sampled once during the first peak runoff event following snow melt in April 1999. These 15 distinct antibiotics were sampled: carbadox, spectinomycin, sulfamethoxazol, erythromycin, sulfamethazine, trimethoprin, erythromycin - H2O, sulfachloropyrizadine, tylosin, ivermectin, sulfadimethoxine, virginiamycin, lincomycin, sulfamerazine, and tetracyclines (total). Analytical results show that 16 of the 31 stream samples had positive detections for antibiotics. Sulfamethazine was detected in 10 samples, tetracycline (total) in 6, and lincomycin in 1. One stream had two detections of a single compound. All of the concentrations were below .5 micrograms/L (parts per billion). The results of this work were first presented at a 1999 USGS meeting titled Effects of Animal Feeding Operations on Hydrologic Resources and the Environment. Proceedings are available at http://water.usgs.gov/owq/AFO/proceedings/afo/index.html.

Findings from this initial reconnaissance laid the groundwork for the the Kolpin et al journal article in Environmental Science and Technology, titled Pharmaceuticals, Hormones, and Other Organic Wastewater Contaminants in U.S. Streams, 1999-2000: A National Reconnaissance; Environ. Sci. Technol., 36 (6), 1202 -1211, 2002

For a more thorough discussion of emerging contamination of water sources, see the USGS Toxic Substances Hydrology Program.