Background
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.
Methods
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 in vitro 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 in vitro exposure-activity cutoffs.
Results
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 disinfection byproducts 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.
Discussion
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.
Conclusion
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.
Citation Information
| Publication Year | 2021 |
|---|---|
| Title | Public and private tapwater: Comparative analysis of contaminant exposure and potential risk, Cape Cod, Massachusetts, USA |
| DOI | 10.1016/j.envint.2021.106487 |
| Authors | Paul Bradley, Denis R. LeBlanc, Kristin 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 Hladik, Luke R. Iwanowicz, Keith Loftin, R. Blaine McCleskey, Carrie A. McDonough, Elizabeth Medlock-Kakaley, Christopher P. Weis, Vickie S. Wilson |
| Publication Type | Article |
| Publication Subtype | Journal Article |
| Series Title | Environmental International |
| Index ID | 70219120 |
| Record Source | USGS Publications Warehouse |
| USGS Organization | California Water Science Center; Leetown Science Center; National Water Quality Laboratory; New Jersey Water Science Center; South Atlantic Water Science Center; Upper Midwest Water Science Center |
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Michael Focazio, PhD (Former Employee)
Environmental Health Program CoordinatorJimmy M Clark
Assistant Director for StudiesEmailPhone