Dana W. Kolpin Darrin A. Thompson Kristin M. Romanok Kelly L. Smalling Sara E. Breitmeyer Mary C. Cardon David M. Cwiertny Nicola Evans R. William Field Michael J. Focazio Laura E. Beane Freeman Carrie E. Givens James L. Gray Gordon L. Hager Michelle L. Hladik Jonathan N. Hoffman Rena R. Jones Leslie K. Kanagy Rachael F. Lane R. Blaine McCleskey Danielle Medgyesi Elizabeth Medlock-Kakaley Shannon M. Meppelink Michael T. Meyer Diana A. Stavreva Mary H. Ward Paul M. Bradley 2023 <div id="ab0005" class="abstract author" lang="en"><div id="as0005"><p id="sp0030">In the United States and globally, contaminant exposure in unregulated private-well point-of-use tapwater (TW) is a recognized public-health data gap and an obstacle to both risk-management and homeowner decision making. To help address the lack of data on broad contaminant exposures in private-well TW from hydrologically-vulnerable (alluvial, karst) aquifers in agriculturally-intensive landscapes, samples were collected in 2018–2019 from 47 northeast Iowa farms and analyzed for 35 inorganics, 437 unique organics, 5 in vitro bioassays, and 11 microbial assays. Twenty-six inorganics and 51 organics, dominated by pesticides and related transformation products (35 herbicide-, 5 insecticide-, and 2 fungicide-related), were observed in TW. Heterotrophic bacteria detections were near ubiquitous (94 % of the samples), with detection of total coliform bacteria in 28 % of the samples and growth on at least one putative-pathogen selective media across all TW samples. Health-based hazard index screening levels were exceeded frequently in private-well TW and attributed primarily to inorganics (nitrate, uranium). Results support incorporation of residential treatment systems to protect against contaminant exposure and the need for increased monitoring of rural private-well homes. Continued assessment of unmonitored and unregulated private-supply TW is needed to model contaminant exposures and human-health risks.</p></div></div> application/pdf 10.1016/j.scitotenv.2023.161672 en Elsevier Juxtaposition of intensive agriculture, vulnerable aquifers, and mixed chemical/microbial exposures in private-well tapwater in northeast Iowa article