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The Effects of Disinfection on Pharmaceuticals in Drinking Water Supplies

Project Purpose:
To use model solutions to examine the effects of chlorination on pharmaceuticals.

Project Description(s):
Reports in the literature show a removal of pharmaceuticals during waste and drinking water treatment, but they do not determine if the compounds are removed from the influent water, or if they are transformed into other chemicals. The purpose of this project was to determine, via benchtop experiments, the fate of pharmaceuticals during chlorination. Fourteen pharmaceuticals were investigated. Pairs of model solutions were prepared for each chemical. To one of the two samples, sodium hypochlorite was added as a disinfectant. The unchlorinated sample was analyzed immediately using liquid chromatography particle beam mass spectrometry. After 48 hours, the chlorinated sample was analyzed, and the unchlorinated sample was re-analyzed to determine if there were any changes over the hold time not due to the chlorination. Two chemicals, acetaminophen and gemfibrozil, had changes in their mass spectra, indicating that they were chlorinated. Six pharmaceuticals, aspirin, aspartame, caffeine, cotinine, 1,7-dimethylxanthine, and 6-methyl-17-hydroxy progesterone acetate, were not affected by the chlorination. The remaining six chemicals, amoxicillin, cephalexin, cimetidine, diltiazem, trimethoprim, and warfarin, were oxidized, but not chlorinated. Reports in the literature show a removal of pharmaceuticals during waste and drinking water treatment, but they do not determine if the compounds are removed from the influent water, or if they are transformed into other chemicals. The purpose of this project was to determine, via benchtop experiments, the fate of pharmaceuticals during chlorination. Fourteen pharmaceuticals were investigated. Pairs of model solutions were prepared for each chemical. To one of the two samples, sodium hypochlorite was added as a disinfectant. The unchlorinated sample was analyzed immediately using liquid chromatography particle beam mass spectrometry. After 48 hours, the chlorinated sample was analyzed, and the unchlorinated sample was re-analyzed to determine if there were any changes over the hold time not due to the chlorination. Two chemicals, acetaminophen and gemfibrozil, had changes in their mass spectra, indicating that they were chlorinated. Six pharmaceuticals, aspirin, aspartame, caffeine, cotinine, 1,7-dimethylxanthine, and 6-methyl-17-hydroxy progesterone acetate, were not affected by the chlorination. The remaining six chemicals, amoxicillin, cephalexin, cimetidine, diltiazem, trimethoprim, and warfarin, were oxidized, but not chlorinated.

Project Outcomes:
This study demonstrated that to get the comprehensive environmental impact of emerging contaminants, it is important to not only look for parent compounds in chlorine-disinfected waters, but also for disinfection/ degradation byproducts that may form.

Contact
Susan Glassmeyer at glassmeyer.susan@epa.gov

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