Denis R. LeBlanc Kristin M. Romanok Kelly Smalling Michael J. Focazio Mary C. Cardon Jimmy Clark Justin M. Conley Nicola Evans Carrie E. Givens James L. Gray L. Earl Gray Phillip C. Hartig Christopher P. Higgins Michelle L. Hladik Luke R. Iwanowicz Keith A. Loftin R. Blaine McCleskey Carrie A. McDonough Elizabeth Medlock-Kakaley Christopher P. Weis Vickie S. Wilson Paul M. Bradley 2021 <div id="abstracts" class="Abstracts u-font-serif"><div id="ab010" class="abstract author" lang="en"><div id="as010"><h3 id="st015" class="u-h4 u-margin-m-top u-margin-xs-bottom">Background</h3><p id="sp0010">Humans are primary drivers of environmental contamination worldwide, including in drinking-water resources. In the United States (US), federal and state agencies regulate and monitor public-supply drinking water while private-supply monitoring is rare; the current lack of directly comparable information on contaminant-mixture exposures and risks between private- and public-supplies undermines tapwater (TW) consumer decision-making.</p></div><div id="as015"><h3 id="st020" class="u-h4 u-margin-m-top u-margin-xs-bottom">Methods</h3><p id="sp0015">We compared private- and public-supply residential point-of-use TW at Cape Cod, Massachusetts, where both supplies share the same groundwater source. TW from 10 private- and 10 public-supply homes was analyzed for 487 organic, 38 inorganic, 8 microbial indicators, and 3<span>&nbsp;</span><i>in vitro</i><span>&nbsp;</span>bioactivities. Concentrations were compared to existing protective health-based benchmarks, and aggregated Hazard Indices (HI) of regulated and unregulated TW contaminants were calculated along with ratios of<span>&nbsp;</span><i>in vitro</i><span>&nbsp;</span>exposure-activity cutoffs.</p></div><div id="as020"><h3 id="st025" class="u-h4 u-margin-m-top u-margin-xs-bottom">Results</h3><p id="sp0020">Seventy organic and 28 inorganic constituents were detected in TW. Median detections were comparable, but median cumulative concentrations were substantially higher in public supply due to 6 chlorine–disinfected samples characterized by<span>&nbsp;</span>disinfection byproducts<span>&nbsp;</span>and corresponding lower heterotrophic plate counts. Public-supply applicable maximum contaminant (nitrate) and treatment action (lead and copper) levels were exceeded in private-supply TW samples only. Exceedances of health-based HI screening levels of concern were common to both TW supplies.</p></div><div id="as025"><h3 id="st030" class="u-h4 u-margin-m-top u-margin-xs-bottom">Discussion</h3><p id="sp0025">These Cape Cod results indicate comparable cumulative human-health concerns from contaminant exposures in private- and public-supply TW in a shared source-water setting. Importantly, although this study’s analytical coverage exceeds that currently feasible for water purveyors or homeowners, it nevertheless is a substantial underestimation of the full breadth of contaminant mixtures documented in the environment and potentially present in drinking water.</p></div><div id="as030"><h3 id="st035" class="u-h4 u-margin-m-top u-margin-xs-bottom">Conclusion</h3><p id="sp0030">Regardless of the supply, increased public engagement in source-water protection and drinking-water treatment, including consumer point-of-use treatment, is warranted to reduce risks associated with long-term TW contaminant exposures, especially in vulnerable populations.</p></div></div></div> application/pdf 10.1016/j.envint.2021.106487 en Elsevier Public and private tapwater: Comparative analysis of contaminant exposure and potential risk, Cape Cod, Massachusetts, USA article