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Development and Application of a Model to Estimate Wastewater Treatment Plant Prescription Pharmaceutical Influent Loadings and Concentrations

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A mass balance model was developed to estimate prescription pharmaceutical loadings to municipal wastewater treatment plants via computation of influent concentrations (C IN). Model estimates of C IN were compared with published data and found to be accurate within an order of magnitude for some 90% of the drugs evaluated. The model was then used to rank prescription drugs on a per-capita mass loading basis for comparison with current research efforts and coupled with two EPISuite programs to generate estimates for environmental exposure. Results showed marked discrepancies between prescription numbers, loadings, exposures, and research conducted, as highlighted by the drug metformin, with the largest projected loading to treatment plants (>28 g per 1,000 people/day), yet only ranking 12th in terms of prescription numbers and no environmental research articles.

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The authors would like to thank the Virginia Environmental Endowment and the G. Unger Vetlesen Foundation for their assistance in funding this research. The authors also would like to thank S. Schlessinger, D. Sanchez, E. Houle, and E. Kurland for their time spent gathering, sorting, and compiling data necessary for model calculations.

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Correspondence to Lisa M. Colosi.

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Ottmar, K.J., Colosi, L.M. & Smith, J.A. Development and Application of a Model to Estimate Wastewater Treatment Plant Prescription Pharmaceutical Influent Loadings and Concentrations. Bull Environ Contam Toxicol 84, 507–512 (2010). https://doi.org/10.1007/s00128-010-9990-3

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  • Pharmaceuticals
  • Wastewater treatment
  • Emerging contaminants