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PFAS in the United States: Occurrence, Fate, Transport, and Exposure
Citation:
Glassmeyer, S. PFAS in the United States: Occurrence, Fate, Transport, and Exposure. To be Presented at 17th Annual EPA Drinking Water Workshop, Cincinnati (via webinar), OH, August 31 - September 03, 2020.
Impact/Purpose:
The first half of the presentation describes the results of sampling the source and treated drinking water at 25 drinking water treatment plants for PFAS and other contaminants of emerging concern. The most striking piece of information from the study is that PFAS was measured in every sample we investigated. The second part of the presentation discusses a sampling study investigating de facto reuse. In this project 236 CECs were measured from upstream of a wastewater treatment plant through drinking water treatment. Related to PFAS, the most important aspect of the study is that the PFAS found in the river system appears to be from non-wastewater sources. Other organic chemicals, such as pharmaceuticals, show a more direct connection to the wastewater effluent.
Description:
Per- and polyfluoroalkyl substances (PFAS) are environmentally stable contaminants of emerging concern, frequently measured in environmental and drinking waters. This study analyzed for 17 PFAS in source- and treated-water samples collected at 25 drinking water treatment plants (DWTPs) across the United States collected between 2010 and 2012. PFAS were quantitatively detected in all 50 samples, with a maximum total PFAS concentration of 1,102 ng/L. The median total PFAS concentration was 21.4 ng/L in the source water and 19.5 ng/L in the treated drinking water. Comparing the total PFAS concentration in source and treated water at each DWTP, only five locations demonstrated statistically significant differences (i.e. P <0.05) between samples, indicating that removal of PFAS during drinking water treatment was not common. The depth and activation status for the granular activated carbon may have been an influential factor at the plants with a significant difference. The environmental persistence of PFAS was evident at six DWTPs. Three DWTPs shared one large river in common as their drinking-water source, while a second set of three DWTPs shared another large river in common for their drinking-water source. The DWTPs in each river basin were separated by 100s to 1000s of kilometers. The PFAS composition at the DWTPs from one river was dominated by perflurooctanoic acid (PFOA), while the PFAS composition at the DWTPs from the other river was dominated by perfluorobutyric acid (PFBA). Modelling gave further insights to the source of PFAS into the water cycle, pointing to environmental sources other than wastewater. Targeted chemical analyses, non-targeted analyses, and bioanalytical tools each provide a unique but incomplete understanding of the contaminants in a sample. The US Environmental Protection Agency and US Geological Survey are collaborating to examine the sources, fates, and potential effects of contaminants of emerging concern (CECs) during de facto water reuse which occurs when treated wastewater is discharged to a source of drinking water. The project sampling design follows a surface flow path, with the collection of grab water samples from upstream of a wastewater treatment plant outfall and downstream to a drinking water treatment plant intake and through the plant to a finished water sample. The study uses an integrated approach that includes a comprehensive analysis of over 200 specific chemicals (e.g. pharmaceuticals, per- and polyfluoroalkyl substances); high resolution mass spectrometry to identify non-targeted (unknown) chemicals; in vitro bioassays (e.g. estrogenicity, androgenicity); rapid whole organism screens to assess cumulative bioactivity; and in vivo tests to address specific exposure and response endpoints. A rigorous quality assurance/quality control protocol was consistently applied from field to laboratory to ensure comparability of results between different techniques. This consistent, integrated approach combines the strength of each technique and builds upon the traditional CEC research approach by including environmental and toxicity endpoint assessments to more fully explore the potential effects to human health and the environment from chemical exposures.