Citation:

Medlock Kakaley, E., N. Evans, M. Cardon, E. Green, J. Conley, L. Gray, P. Bradley, K. Smalling, AND K. Romanok. Effects-based tools to support consumers in tapwater use decisions: A multi-case study summary. National Water Quality Monitoring Council Meeting, Virginia Beach, VA, April 24 - 28, 2023.

Impact/Purpose:

The abstract summarizes several case studies, conducted in collboration with the US Geological Survey, that were designed to address a critical lack of directly comparable data on contaminant exposures in different tapwater sources, as well as document potential simultaneous mixtures exposures to inorganic, organic, and/or microbial contaminants of human-health concern. Over the course of seven cases studies, hundreds of point-of-use samples were taken from residental volunteers from geographical locations/communities of increased exposure susectability. This summary focuses on the results of the EPA-generated data from water sample extract analyses using in vitro effects-based methods, or bioassays, specific to endocrine disurption compounds. Overarching onclusions and implications based on biological activity detection patterns are provided. More broadly, the results support previous calls for continued systematic, quantitative assessments of contaminant exposures and associated bioactivities in tapwater, especially in unregulated and unmonitored locations, to support models of drinking-water contaminant exposures and related risks at the point of use.

Description:

ABSTRACT: We previously detected biological activity, indicative of endocrine disrupting compounds, in surface and source waters. However, the paucity of chemical contaminant occurrence data in unmonitored private-supply point-of-use (POU) tapwater, as well as the potential for unknown adverse health effects from emerging contaminants and contaminant mixtures exposures obfuscates consumer risk management decisions. USEPA and U.S. Geological Survey scientists collaborated with universities, Tribal, and non-profit partners, to produce directly comparable occurrence data sets of public and private tapwater supplies, as well as of bottled water. Community volunteers (POU water samples) across seven case studies were selected based on exposure susceptibility (e.g., impacted source waters, geographical location, surrounding soil composition, and aging distributions systems among others). Using in vitro cell-based tools and a tiered screening process, we tested solid phase-extracted water samples for biological activity including, estrogenic (T47d-KBluc), (anti)androgenic (CV1-chAR), and glucocorticoid (CV1-hGR) activity. No public-supply POU tapwater sample contained biological activity above in vitro method detection limits, no detections of glucocorticoid or antiandrogenic activity were detected in any sample, and bottled water did not contain estrogenic activity. Estrogenic (detected most often and in highest concentrations; ng Estradiol equivalents/L) and androgenic activity (ng Dihydrotestosterone equivalents/ L) were detected in impacted source and private supply POU samples only. Overall, estrogenic activity ranged 0.01 – 2.97 ng E2Eq L-1 (median: 0.05 ng E2Eq L-1), androgenic activity ranged 0.07 – 0.17 ng DHTEq L-1 (median: 0.15 ng DHTEq L-1), and aging distribution systems did not alter biological activity levels in POU samples. All estrogenic (3.8 ng E2Eq L-1) and androgenic (11 ng DHTEq L-1) detections fell below previously reported human-health Effects-Based Trigger (EBT) values for drinking water. Results were consistent with our previous case studies in that estrogenic, androgenic and glucocorticoid activity were detected in source waters, but contemporary treatment systems typically eliminate activity to below detection for these in vitro methods. However, private supplies sourced from ground water have potential to contain endocrine activity especially when heavily impacted by local agriculture or anthropogenic waste. Abstract does not reflect Agency views or policy.  

Record Details: