This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.
Article Cite This: Environ. Sci. Technol. 2018, 52, 13972−13985
pubs.acs.org/est
Environ. Sci. Technol. 2018.52:13972-13985. Downloaded from pubs.acs.org by 91.204.14.221 on 01/14/19. For personal use only.
Reconnaissance of Mixed Organic and Inorganic Chemicals in Private and Public Supply Tapwaters at Selected Residential and Workplace Sites in the United States Paul M. Bradley,*,† Dana W. Kolpin,‡ Kristin M. Romanok,§ Kelly L. Smalling,§ Michael J. Focazio,∥ Juliane B. Brown,⊥ Mary C. Cardon,# Kurt D. Carpenter,¶ Steven R. Corsi,□ Laura A. DeCicco,□ Julie E. Dietze,○ Nicola Evans,# Edward T. Furlong,△ Carrie E. Givens,▽ James L. Gray,△ Dale W. Griffin,⬡ Christopher P. Higgins,⊥ Michelle L. Hladik,■ Luke R. Iwanowicz,● Celeste A. Journey,† Kathryn M. Kuivila,¶ Jason R. Masoner,▲ Carrie A. McDonough,⊥ Michael T. Meyer,○ James L. Orlando,■ Mark J. Strynar,# Christopher P. Weis,▼ and Vickie S. Wilson# †
United States Geological Survey, Columbia, South Carolina 29210, United States United States Geological Survey, Iowa City, Iowa 52240, United States § United States Geological Survey, Lawrenceville, New Jersey 08648, United States ∥ United States Geological Survey, Reston, Virginia 20192, United States ⊥ Colorado School of Mines, Golden, Colorado 80401, United States # United States Environmental Protection Agency, Durham, North Carolina 27709, United States ¶ United States Geological Survey, Portland, Oregon 97201, United States □ United States Geological Survey, Middleton, Wisconsin 53562, United States ○ United States Geological Survey, Lawrence, Kansas 66049, United States △ United States Geological Survey, Lakewood, Colorado 80225, United States ▽ United States Geological Survey, Lansing, Michigan 48911, United States ⬡ United States Geological Survey, St. Petersburg, Florida 33701, United States ■ United States Geological Survey, Sacramento, California 95819, United States ● United States Geological Survey, Kearneysville, West Virginia 25430, United States ▲ United States Geological Survey, Oklahoma City, Oklahoma 73159, United States ▼ United States National Institute of Environmental Health Sciences/NIH, Bethesda, Maryland 20892, United States ‡
S Supporting Information *
ABSTRACT: Safe drinking water at the point-of-use (tapwater, TW) is a United States public health priority. Multiple lines of evidence were used to evaluate potential human health concerns of 482 organics and 19 inorganics in TW from 13 (7 public supply, 6 private well self-supply) home and 12 (public supply) workplace locations in 11 states. Only uranium (61.9 μg L−1, private well) exceeded a National Primary Drinking Water Regulation maximum contaminant level (MCL: 30 μg L−1). Lead was detected in 23 samples (MCL goal: zero). Seventy-five organics were detected at least once, with median detections of 5 and 17 compounds in self-supply and public supply samples, respectively (corresponding maxima: 12 and 29). Disinfection byproducts predominated in public supply continued...
Received: Revised: Accepted: Published: © 2018 American Chemical Society
13972
August 17, 2018 October 14, 2018 November 2, 2018 November 21, 2018 DOI: 10.1021/acs.est.8b04622 Environ. Sci. Technol. 2018, 52, 13972−13985
Article
Environmental Science & Technology
samples, comprising 21% of all detected and 6 of the 10 most frequently detected. Chemicals designed to be bioactive (26 pesticides, 10 pharmaceuticals) comprised 48% of detected organics. Site-specific cumulative exposure−activity ratios (∑EAR) were calculated for the 36 detected organics with ToxCast data. Because these detections are fractional indicators of a largely uncharacterized contaminant space, ∑EAR in excess of 0.001 and 0.01 in 74 and 26% of public supply samples, respectively, provide an argument for prioritized assessment of cumulative effects to vulnerable populations from trace-level TW exposures.
■
INTRODUCTION Establishment of physical and chemical water treatment and subsequent water quality regulation and monitoring frameworks in the United States (US), Europe, and elsewhere fundamentally improved the quality and safety of drinking water.1−3 Continued enhancements are dictated by an expanding environmental contaminant space (new chemicals, improved detection),4,5 broader awareness of the mechanistic diversity linking human health to chemical and biological contaminant exposures,6−8 evolving societal engagement and consumer acceptability,9−12 and episodic, water-borne outbreaks.13−15 US public supply drinking water safety is regulated by the US Environmental Protection Agency (EPA) under the Safe Drinking Water Act (SDWA) in collaboration with drinking water utilities and state and local health agencies.16−18 EPA systematically explores suspected contaminant exposures in public supply drinking water under the Unregulated Contaminant Monitoring Rule (UCMR)19 and prioritizes potential hazards and regulatory determinations on a chemicalby-chemical basis through the Contaminant Candidate List process.20 While regulated chemicals are routinely monitored at drinking water facilities prior to distribution,16−18 only select chemicals (e.g., disinfection byproducts (DBP) and disinfectant residuals,21,22 lead and copper23,24) are routinely monitored at the point-of-use (tapwater, TW), and probable exposures and effects of mixtures of inorganic and organic contaminants in TW are recognized data gaps.25,26 The current safety and long-term sustainability of US TW are rising public health concerns9−12,27,28 for several reasons, including: (1) increased dependence on water reuse (intentional and de facto) to meet growing demands (e.g., drinking water, wastewater disposal, and environmental flow requirements),29−33 (2) prevalence of contaminant mixtures in surface and groundwater drinking water sources4,34−36 and in finished drinking water,5,37,38 (3) increased disconnect between drinking water regulation/treatment and documented environmental contaminant complexity,5,35,37−39 (4) aging drinking water infrastructure40,41 and legacy plumbing materials,42 (5) new research linking public health outcomes to low-level contaminant exposures,6−8 (6) public health trade-offs of intended (e.g., disinfection) and unintended (e.g., DBP) water treatment outcomes,43,44 and (7) high-visibility water quality failures.15,45−47 The relative lack of information on TW exposures is particularly concerning to the public and public health researchers because leaks, cross-connections, back-siphonage, and corrosion15 in the distribution system can lead to known or suspected public health outcomes.45−47 Likewise, improved understanding of contaminant exposures in US self-supplied TW is critical48,49 because more than 40 million people in the US depend on private wells for drinking water,29,50 the EPA is not authorized to monitor or regulate individual water systems (≤14 connections, ≤24 people) under the SDWA,51 and owner self-monitoring is rare49,52 due to high analytical costs, disincentivizing disclosure regulations (e.g., property sale) in some states, and over-reliance on organoleptic quality (e.g., taste and odor) as an indicator of safety.49,52−54
To begin to address these knowledge gaps, the USGS, EPA, and National Institute of Environmental Health Sciences conducted a nationally distributed, pilot-scale, synoptic assessment of chemical exposures in 13 home (6 private self-supply, 7 public supply) and 13 workplace point-of-use drinking waters (26 total) in 11 US states. Based on findings of the recent USGS/EPA surface water mixed-contaminant exposure study (which included 14 target chemical methods, 916 total analytes, and more than 400 detected organics),4,34,55 herein we assess TW exposures based on 482 unique organics and 19 inorganics. Potential human health concerns are explored based on (1) designed bioactive chemical (e.g., pesticides, pharmaceuticals) exposures,4 (2) SDWA national primary drinking water regulation (NPDWR) standards (maximum contaminant level [MCL] and MCL goals [MCLG])17,18 and public health advisories and World Health Organization (WHO) drinking water guideline values,56 (3) in vitro bioassay results,34 and (4) cumulative exposure−activity ratios (∑EAR).57−62 Preliminary home/workplace and public/ self-supply TW exposure comparisons were secondary goals.
■
MATERIALS AND METHODS Site Selection. TW sites were selected from USGS employee volunteers to ensure national distribution and a cross-section of public/self-supply and paired home/workplace settings. Twentyfive TW samples were collected in May−September 2016 from 11 states, including California (CA), Colorado (CO), Florida (FL), Iowa (IA), Kansas (KS), Michigan (MI), New Jersey (NJ), Oklahoma (OK), Oregon (OR), South Carolina (SC), and Virginia (VA) (Figure 1). A sample also was collected from a single, 19 L (5 gallon) water bottle station at the IA workplace location. Sample Collection. Complete sampling details are provided elsewhere.63 In brief, new gloves were used to prepare a clean polyethylene work surface and prepare bottles. Fresh gloves were used to fill and cap bottles. Field parameters (pH, temperature, and specific conductivity) were measured on-site. All samples were shipped double-bagged, on ice, overnight to respective laboratories.63 Taps were sampled (cold water) without precleaning, screen removal, or flushing. First-draw, 6 h stagnant sampling, as stipulated for 1991 Lead and Copper Rule (LCR compliance monitoring,23,24 was not required in this study, and same-day, prior use was typical. Analytical Methods. TW samples were analyzed by USGS using 12 target organic (482 unique analytes) and 1 inorganic (19 analytes) methods (Table S1).63 Analyses conducted at 3 USGS laboratories included the (1) National Water Quality Laboratory (NWQL) in Denver, Colorado (volatile organic compounds (VOC);64 steroid hormones and related compounds;65 organic wastewater indicator (OWI) compounds;66 human-use pharmaceuticals, pharmaceutical metabolites, and polar organic compounds;67 and trace elements68,69); (2) Organic Geochemistry Research Laboratory (OGRL) in Lawrence, Kansas (acetamide herbicides and degradation products;70 glyphosate, glufosinate, and aminomethylphosphonic acid;71 steroid hormones and phytoestrogens;72 triazine and phenylurea herbicides;73 and antibiotics74); and (3) Organic Chemistry Research Laboratory 13973
DOI: 10.1021/acs.est.8b04622 Environ. Sci. Technol. 2018, 52, 13972−13985
Article
Environmental Science & Technology
Figure 1. National distribution of states from which matched home and workplace TW samples were collected during the 2016 pilot study.
(∑EAR).57,88−90 EAR ≥ 1 indicates exposures shown to modulate molecular targets in vitro, whereas EAR ≤ 1 suggests proportionately lower probability of biological activity. Nonspecific end point, baseline, and unreliable response−curve assays were excluded (as described in refs 57 and 88−90). ∑EAR results and exclusions are summarized in Tables S9−S11.
(OCRL) in Sacramento, California (pesticide and pesticide degradates;75 diuron, diuron degradates, and neonicotinoid insecticides;76 and DBP77). Per/polyfluoroalkyl substances (PFAS) were analyzed78−80 at the EPA, Colorado School of Mines (CSM), and NWQL. Pharmaceutical samples were syringe filtered (0.7 μm nominal pore size, glass fiber) in the field. Pharmaceutical and VOC bottles were pretreated with ascorbic acid to neutralize chlorine/chloramine. In vitro estrogen (ER), androgen (AR), and glucocorticoid (GR) activities were assessed by EPA34,55 and USGS.34,55,81 Results are in Tables S2−S5 and at Romanok et al.82 Data Handling, Quality Assurance, Statistics, and ∑EAR Analysis. Quantitative (≥limit of quantitation, ≥LOQ) and semiquantitative (between LOQ and long-term method detection limit, MDL83,84) results were treated as detections.83,85 Quality assurance/quality control included analyses of field blanks from two randomly selected sites (both workplace, all analytes), laboratory blanks and spikes, and stable isotope surrogates. No analytes were detected above the reporting limit in inorganic field blanks. Lidocaine (1.61 ng L−1) and 1, 1-difluoroethane (0.014 μg L−1) were detected in organic field blanks, with lidocaine also detected in TW samples (range 1.41− 23.7 ng L−1). Lidocaine detections below the LOQ (15.2 ng L−1) were removed from the interpretive data set. The median stable isotope surrogate recovery for all samples and relevant methods (DBP, hormone, pesticide, and pharmaceutical) was 88% (interquartile range: 73−100%). Blank and surrogate/spike recovery summaries are in Tables S6−S8. Statistically significant (α = 0.05) differences between TW samples were assessed by nonparametric Kruskal−Wallis one-way analysis of variance (ANOVA) on ranks and Dunn multiple comparisons on ranks. A screening-level assessment of potential cumulative effects of mixed organic contaminants in each TW sample was conducted58 by summing (presumptive concentration addition model86,87) individual EAR (ratio of detected concentration to activity threshold concentration from ToxCast high-throughput screening data59,60) to provide site-specific cumulative EAR
■
RESULTS AND DISCUSSION TW Inorganic Concentrations and NPDWR Comparisons. Trace element results are presented in Figure S2 and Table S2. NPDWR standards (MCL and MCLG) or action levels (AL) are promulgated17,18 for 10 of the 18 inorganic analytes detected in this study (Figure S2 and Table S2). Consistent with compliance monitoring and corrective actions by public water utilities, EPA, and primacy agencies under the SDWA, no inorganic contaminants were detected in public supply tapwater in exceedance of NPDWR MCL. Only uranium (U) was found to exceed its NPDWR MCL of 30 μg L−1 (corresponding WHO guideline56 30 μg L−1) in one self-supply home (61.9 μg L−1) located in a historical uranium mine area.91,92 Based on this result, a point-of-use reverse-osmosis treatment was installed by the homeowners, with follow-up raw (U = 58.1 μg L−1) and treated (U = 0.07 μg L−1) samples confirming the original result and successful reduction of U exposure, respectively. This single MCL exceedance illustrates the human health risks that can remain undetected in unmonitored self-supply TW.48,49,52,54 The fewest detections (3) and lowest cumulative concentrations (1.5 μg L−1) of inorganics were observed in the single commercial water bottle station sample included in this study. U was detected above the MCLG (zero) in 18 TW samples (median: 0.06 μg L−1). No significant differences (p-value = 0.611; Kruskal−Wallis) in U concentrations were observed between self-supply home, public supply home, and public supply workplace samples. Adverse human health effects of U are well-documented.93,94 Recent studies have specifically linked drinking water U exposure to nephrotoxicity95,96 and osteotoxicity97 in humans and to estrogen-receptor-mediated effects in mice.98 13974
DOI: 10.1021/acs.est.8b04622 Environ. Sci. Technol. 2018, 52, 13972−13985
Article
Environmental Science & Technology
greater than the 1 μg L−1 method detection limit (MDL) stipulated for public supply compliance monitoring, and none exceeded the 5 μg L−1 practical quantitation limit (PQL).23,24 Improved understanding and communication of the adverse health risks of low-level TW inorganic contaminant exposures is needed to appropriately address potential public concerns arising from increasingly sensitive analytical methods. TW Target Organic Concentrations. TW organic results are presented in Figures 2−4 and Table S3. Seventy-five organics were detected at least once at concentrations up to 66 μg L−1 for trichloromethane (Figure 2, Table S3). Among these, 22 (29%) were detected only once at concentrations as high as 0.60 μg L−1, and 33 (44%) were detected at 2 or fewer sites. The maximum numbers of detected organic analytes per site were 12 and 29 for self-supply and public supply TW sample groups, respectively, with corresponding maximum cumulative concentrations of 0.70 and 70.5 μg L−1 (Figures 3 and Table S3). Cumulative detections and concentrations per site differed (p-value ≤0.013) between self-supply (median: 4.5 compounds; 0.21 μg L−1) and public supply (median: 17 compounds; 19.6 μg L−1) but not between home and workplace public supply groups (Figures 4A and B). Consistent with chlorine-based disinfection, DBP (16 total) were present in all public supply samples at cumulative concentrations ranging 0.8−69.9 μg L−1 (median: 19.6 μg L−1), but with the exception of trichloromethane (
