Lead in drinking water at North Carolina childcare centers: Piloting a citizen science-based testing strategy

Journal Pre-proof Lead in drinking water at North Carolina childcare centers: Piloting a citizen sciencebased testing strategy Jennifer Hoponick Redmon, Keith E. Levine, Anna M. Aceituno, Kristin Litzenberger, Jacqueline MacDonald Gibson PII:

S0013-9351(20)30018-9

DOI:

https://doi.org/10.1016/j.envres.2020.109126

Reference:

YENRS 109126

To appear in:

Environmental Research

Received Date: 13 September 2019 Revised Date:

13 November 2019

Accepted Date: 7 January 2020

Please cite this article as: Redmon, J.H., Levine, K.E., Aceituno, A.M., Litzenberger, K., Gibson, J.M., Lead in drinking water at North Carolina childcare centers: Piloting a citizen science-based testing strategy, Environmental Research (2020), doi: https://doi.org/10.1016/j.envres.2020.109126. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Inc.

Communication

Citizen Science Testing

Risk Factors

Own/ Lease

Shipping

Lab Analysis

Potential Risk Mitigation Fixture Type

Distance to Water Treatment

Center Lead > 15 µg/L Sample Location

Clean Water at the Tap in Childcare Centers and Schools

Year Built Center Type

TITLE Lead in Drinking Water at North Carolina Childcare Centers: Piloting a Citizen ScienceBased Testing Strategy

AUTHORS Jennifer Hoponick Redmon1*, Keith E. Levine1, Anna M. Aceituno1, Kristin Litzenberger1, and Jacqueline MacDonald Gibson2 1. RTI International, Research Triangle Park, North Carolina 2. School of Public Health, Indiana University, Bloomington, Indiana *Corresponding Author: Jennifer Hoponick Redmon 3040 Cornwallis Road, Research Triangle Park, North Carolina 27709 919-541-6245 (work) 919-370-2832 (cell) [email protected]

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ABSTRACT Background: Drinking water is a lingering hazard in the effort to eliminate childhood exposure to lead (Pb), a neurotoxin that affects cognitive and behavioral development. This study characterized Pb in municipal drinking water at North Carolina, US, childcare centers. The study also demonstrates a scalable, citizen science-based drinking water testing strategy for Pb at childcare centers. Methods: Licensed childcare centers in four North Carolina counties were recruited. One administrator per center completed a survey and was trained to collect first-draw drinking water samples in their center. Samples were shipped with pre-paid labels for laboratory analysis using inductively coupled plasma mass spectrometry. Multilevel logistic regression and Bayesian network analysis were used to identify factors associated with a risk of exceeding the 1 µg/L American Academy of Pediatrics reference level and the US Environmental Protection Agency (US EPA) 15 µg/L treatment-based action level. Results were provided to centers along with risk mitigation recommendations. Results: Of 103 enrolled centers, 86 completed the study, submitting 1,266 drinking water samples in total. Approximately 77% of drinking water samples contained detectable Pb (> 0.1 µg/L), and 97% of centers had at least one drinking water sample with detectable Pb. More than 63% of centers had at least one drinking water sample with > 1 µg/L Pb, and 17% of centers had at least one drinking water sample with Pb above 15 µg/L. There was high variability in Pb concentrations at water points within the same center. Discussion: This study demonstrated a high prevalence and variability of Pb in first-draw samples of drinking water at childcare centers in North Carolina, US. Results underscore the importance of testing for Pb at every tap used for drinking and cooking in childcare centers. The use of employees as citizen scientists is a feasible strategy to identify Pb in specific drinking water taps.

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KEYWORDS: DRINKING WATER; CHILDCARE CENTERS; LEAD (PB); TESTING STRATEGY; CITIZEN SCIENCE ABBREVIATIONS Pb – Lead EPA – Environmental Protection Agency MCL – Maximum Contaminant Level NSF – National Science Foundation ANSI – American National Standards Institute

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FUNDING SOURCES The authors would like to thank RTI International for providing internal research and development grants to conduct the Clean Water for Carolina Kids pilot study, and for hosting Dr. Jackie MacDonald Gibson as an RTI Scholar during 2017-2018. This study did not include research on human subjects or experimental animals. The authors declare no conflicts of interest.

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1.0 INTRODUCTION Lead (Pb) exposure is known to impair children’s cognitive and behavioral development.1-4 Deficits from early childhood Pb exposure persist across grades, even with blood Pb levels below 5 µg/dL.5-7 Children can be exposed to Pb throughout their environment. Homes and childcare centers built prior to 1978 are likely to contain Pb-based paint and dust.89 Childcare centers may contain Pb in soil from leaded gasoline use before its phased ban from 1973 to 1996.10-12 Pb has also been found in childcare toys, baby food, candies, and spices.13-16 Another potential source of Pb exposure is tap water. While the United States (US) Environmental Protection Agency (EPA) estimates that drinking water may comprise 20% of a person’s total Pb exposure, and 40-60% for formula-fed infants, data are lacking to identify what levels of Pb are in childcare centers nationally, and whether the proportion of drinking water exposure is greater since the Pb paint and gasoline bans.17,18 In most cases, drinking water at childcare centers and schools is not required to be tested for Pb. Federal regulations only require Pb testing in drinking water at childcare centers in two instances. First, if a childcare center or school is on well water, it should be tested for Pb under the federal US Safe Drinking Water Act. Second, the federal US Lead and Copper Rule requires public water systems to collect drinking water samples at the tap every three years for a small subset of selected water customers based on the public water system size to determine if their treatment-based regulation is met.19 Because of limited federal regulatory requirements for at-the-tap monitoring of Pb, little information is available about Pb in drinking water at childcare centers—arguably one of the most important places to monitor due to the life-long impacts of early childhood Pb exposure. A handful of studies in the past 15 years have tested Pb in school tap water, reporting high Pb concentrations in some locations.20-24 To our knowledge, only two prior peer-reviewed studies have investigated Pb in water in North American childcare centers served by municipal water supplies: a 2014 study of water in large buildings including childcare centers in Canada, and a 2009 study of preschools and schools in Kansas.23 Those studies reported variable concentrations of Pb in drinking water. As of 2019, 11 states and New York City have passed regulations to require licensed childcare centers to test their tap water for Pb in an effort to address the gap in current federal regulations (Table S1). In addition to limited requirements for Pb testing of drinking water in childcare centers and schools, there are also critical gaps in health-based standards for Pb in drinking water. In the US, recent state or local regulations refer to the treatment-based action level of 15 µg/L or parts per 5

billion (ppb), which is largely based on technical feasibility and cost considerations for public utilities.25 Under the Safe Drinking Water Act, unenforceable maximum contaminant level (MCL) goals are set for contaminants based on health considerations alone, while setting standards for enforceable MCLs include other considerations such as treatment feasibility and practical analytical limits. To date, an MCL has never been set for lead, despite an unenforceable MCL goal of 0. In 2016, in part prompted by the events in Flint, the American Academy of Pediatrics recommended that the EPA establish a reference level of 1 µg/L for Pb in water to protect children’s health.26,27 The US Centers for Disease Control also specify that access to safe drinking water should be one of the key considerations for safe siting of an early-childhood education building.28 Known risk factors for the presence of Pb in drinking water include corroded piping and plumbing, the presence of Pb service lines, and corrosive water that may not have proper corrosion control. Corrosive water can break down pipes, fittings, and solder to leach Pb into drinking water as it travels to the tap. Progressive US restrictions on Pb in piping and plumbing went into effect in 1988 and 2014, but large swaths of water infrastructure and plumbing pre-date these plumbing regulations.29 Homes built before 1988, the effective year of the “Pb pipe ban,” are more at risk for Pb pipes, fixtures, and solder. Homes built after 1988 may still contain distribution piping to the home with Pb service lines. Galvanized iron pipes, copper pipes with Pb soldering, and brass fixtures within the home can also be a source of Pb. Even in buildings built after 2014, the effective date of the most recent plumbing regulation, 0.25% Pb is allowable in piping and 0.2% is legal in other plumbing materials.13,30-35 Highly publicized recent events in multiple cities, from Flint, Michigan36,37 to Newark, New Jersey, have revealed the need for improved approaches to Pb testing, communication, and risk mitigation in municipal drinking water systems.34,38,39 To build on the limited prior evidence about Pb occurrence in municipal tap water in US childcare centers, we piloted a scalable citizen science approach to water testing, risk communication, and mitigation in North Carolina, US childcare centers and elementary schools with Head Start pre-Kindergarten programs. Our objectives were to (1) demonstrate a protocol for childcare centers to conduct water testing for Pb, ( 2) estimate Pb prevalence in North Carolina childcare centers on public water systems, and (3) determine factors influencing the risk of elevated Pb at centers with municipal water. This is the first known North American study characterizing Pb occurrence in childcare centers with trained childcare administrators acting as citizen scientists to collect drinking water samples using a mail-out test kit.

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2.0 MATERIALS AND METHODS 2.1 Study Information Recruitment, Enrollment, Site Visit, and Survey. Licensed childcare centers and Head Start preKindergarten programs on public water supplies were identified within four North Carolina counties. Study invitation letters detailing the study were emailed to childcare centers.40 Follow-up screening phone calls were made and the study was also publicized in press and on social media. The target enrollment was met in Guilford and Durham Counties (13%), exceeded in Orange County (36%), and lower than target in Wake County (9%). In total, 103 centers completed enrollment, and 86 centers provided drinking water samples using the test kit (84% completion) (Table 1; Figures S1 and S2). Each center was visited during May to October 2017 to conduct a brief survey with the center administrator, to identify drinking water taps throughout the building(s), and to complete citizen science training. Information on treated water within the study area was obtained from publicly available water quality reports (see Table S2). The study did not involve human subjects and therefore did not collect data on center capacity, enrollment, or demographics. Citizen Science Training and Testing Protocol. During the site visit, RTI field staff trained the childcare administrator designated to conduct the sampling on how to collect and ship drinking water samples in a scientifically robust manner. A drinking water sample test kit was provided to each trained citizen scientist (Figure S1).27,41-43 The drinking water sample testing protocol is based the EPA’s 3Ts (Training, Testing, and Taking Action) for Reducing Lead in Drinking Water in Schools and Childcare Facilities guidance.44 In a modification to the 3Ts, citizen scientists at participating centers were instructed to collect samples on a Monday morning instead of a shorter eight to 18-hour stagnation period, because most centers are vacant over the weekend and thus routine stagnation periods are often more than 18 hours. Drinking Water Sample Collection. First-draw morning samples were collected by administrators trained to collect water samples. RTI’s test kits supplied the trained administrator with a 250 milliliter (mL) wide mouth round high-density polyethylene (HDPE) bottle for each water sampling point. Each bottle was pre-cleaned to EPA standards by the manufacturer as documented by a certificate of quality environmental compliance. The citizen scientist matched sampling locations in numbered order corresponding to the center-specific chain-of-custody document and associated pre-labeled bottles. Once sampled, the labeled bottles were closed tightly

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and placed in the provided box with the completed chain-of-custody form, closed, and set out for same-day pickup with the pre-printed shipping label affixed. Laboratory Analysis. Samples were shipped to RTI overnight and logged upon arrival. After samples arrived, each sample was acidified and held for 16 hours prior to pH verification and the process of sample digestion and analysis. The samples were subsequently analyzed for Pb via inductively-coupled plasma mass spectrometry using EPA Method 200.8.45 The detection limit was 0.1 µg/L. Quality assurance and quality control measures were completed for all samples. Risk Communication and Mitigation. Prior to enrollment, a flyer on the study, its purpose, and potential risk mitigation recommendations was provided to childcare centers in recruitment emails. After drinking water samples were analyzed, laboratory results were provided to centers along with specific recommendations for risk mitigation.

2.2 Statistical Analysis Separate analyses were conducted to identify factors associated with Pb occurrence at any water point within a center above either 1 µg/L Pb (the AAP reference level) or 15 µg/L Pb (the public utility treatment-based action level). In addition, a multi-level regression analysis was conducted to identify factors associated with measured Pb concentrations across and within centers. Similar to the logistic regression, the network model included distance from the water treatment plant, center type, and water point location as risk factors. However, the network model also evaluated building age, building ownership (owned versus leased), and fixture type (Figure 2a; Table S3). Center-Based Risk Factors Influencing Pb Above 1 or 15 µg/L in at Least One Center Tap. To identify factors influencing whether any water point within a given childcare center exceeded either 1 or 15 µg/L, two approaches, logistic regression and Bayesian network analysis, were compared. All variables and interactions with p<0.2 were included in the final model. For both types of models, the dependent variable was whether any water tap in a given center had more than the specific threshold concentration (either 1 or 15 ppb, with separate models for each). Because Bayesian network models have shown high predictive accuracy in many applications, a study-specific Bayesian network model was built as a secondary analysis to identify factors associated with having at least one water tap exceeding either 1 or 15 µg/L.46 Risk Factors Influencing Pb Concentration at a Specific Tap. Multilevel regression was used to analyze how characteristics of (1) individual water points, (2) childcare centers, and (3) water

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systems influence Pb concentrations at a specific tap within a center. The multi-level regression predicts the actual concentration, which may take an infinite number of possible values from the detection limit to the maximum observed. Variables and interaction terms with p<0.2 were retained in the final model. Model Validation. The logistic regression and Bayesian network models were tested using four-fold cross-validation. The data set was divided at random into four segments, each model was learned using three of the segments, and then the accuracy of each in predicting the held-out samples was estimated. This process was repeated 20 times to generate 90% confidence intervals. The area under the receiver-operating characteristic curve was used as a metric of model accuracy as it measures the trade-off between sensitivity and specificity, with 1.0 considered a perfect classifier.50 Additional methods information is provided in Appendix A.

3.0 RESULTS 3.1 Summary Statistics Samples. Of 1,266 drinking water samples, approximately 77.3% (978) of the 1,266 tested water samples contained detectable Pb above 0.1 µg/L. For drinking water samples with detectable Pb, 25.5% (249) exceeded the 1-µg/L AAP reference level, and 1.74% (17) exceeded the 15-µg/L

Figure 1. (a) The distribution of Pb concentrations for the 1,266 drinking water samples from center taps, excluding bottled water (left). (b) Maximum Pb concentration in the 86 participating childcare centers (right).

EPA treatment-based action level (Figure 1a). Centers. Among the 86 participating childcare centers, 97% (83) had detectable Pb in at

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least water point. Of centers with detectable Pb, 63% (52 centers) had at least one water point that exceeded the 1-µg/L American Academy of Pediatrics reference level. Additionally, 17% (14) exceeded the 15 µg/L treatment-based action level for public utilities (Figure 1b).26 Tables 1 and 2 report summary statistics for the measured Pb concentrations for all water samples. The mean Pb concentration across all taps was 1.27 µg/L (standard deviation: 5.59 µg/L). The maximum Pb concentration, 121 µg/L, was measured in an unfiltered kitchen tap. Samples collected per center ranged from 2 (residence) to 153 (elementary school) with a median of 6. Building ages ranged from 1912 to 2017, with a mean of 1985. Water treatment plant distance ranged from one to 16.7 miles with a median of 4.45 miles. The distribution of distances was rightskewed, with the mean distance (5.63 miles) greater than the median (Figure S3). Samples were predominantly collected from dedicated childcare centers (76%), followed by home-based centers (12%), and elementary schools (12%). Approximately 55% of centers owned their building, while 39% leased. Sample collection locations typically included classrooms (48%), bathrooms (23%), and kitchens (17%). Fixture types primarily included sinks (74%) and water fountains (11%). Bottled water data were excluded from all statistical analyses since it was not tap water (although the samples were analyzed to ensure it was safe for consumption, and none contained detectable lead). In total, 49 centers (57%) knew of renovations in the building that may have modified plumbing or fixtures, though exact changes were unclear in most cases. Table 1. Summary statistics for continuous variables collected in this study. Variable Sample N Mean (SD) Min. Pb concentration ( µg/L ) Samples per childcare center Distance to water treatment plant (miles) Year building built

1266 -86

1.27 (5.59) 14.9 (21.2) 5.63 (3.77)

Median

<0.100 2 1

0.29 6 4.45

90th Percentile 1.97 36.5 11.0

Max. 121 153 16.7

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1985 1912 1993 2009 2017 (22.4) NOTES: Samples with concentrations below the detection limit were assigned a value of half 0.05 µg/L (half the detection limit). Bottled water samples were excluded from all analyses. Statistics based on the 86 participating centers. Table 2. Characteristics of childcare centers and water points included in this study Type of childcare center Dedicated childcare center 978 Home-based childcare center 153 School 153 Ownership status Own 710 Lease 499 Not known 75 Sample collection location

76.2% 11.9% 11.9% 55.3% 38.9% 5.8%

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Bathroom Classroom Common area Kitchen Outside Staff room Fixture type Bottled water Cooler Filter Fountain Hose Ice maker Pitcher Refillable bottles Sink Public water supply provider (city of) Cary Chapel Hill/ Carrboro Durham Greensboro High Point Raleigh Note the 18 bottled water samples were not used in statistical analysis.

293 612 100 217 47 15

22.8% 47.7% 7.8% 16.9% 3.7% 1.2%

18 48 48 138 34 2 12 3 981

1.4% 3.7% 3.7% 10.7% 2.6% 0.2% 0.9% 0.2% 76.4%

176 139 361 323 121 164

13.7% 10.8% 28.1% 25.2% 9.4% 12.8%

3.2 Center-Based Risk Factors Influencing Pb Occurrence in at Least One Drinking Water Sample Risk of Pb > 15 µg/L. The logistic regression model indicated that the water system serving the childcare center was not associated with the risk of Pb occurrence above 15 µg/L, although centers located 3.1-6.8 miles from a water treatment plant were marginally less likely to contain a water point with Pb above 15 µg/L than centers closer to or farther from the treatment plant (Table 3a, odds ratio=0.18, p<0.10). Home-based childcare centers were significantly less likely than dedicated childcare centers or schools to contain elevated Pb (Table 3a: odds ratio=0.12, p=0.023). Water points with elevated Pb were significantly less likely to occur in classrooms than in other locations (Table 3a: odds ratio=0.14, p=0.048). Risk of Pb > 1 µg/L. The logistic regression model also identified center type as significantly associated with having at least one water point with more than 1 µg/L of Pb. Homebased childcare centers were significantly less likely to have any tap with Pb above 1 µg/L than dedicated childcare centers or schools (Table 3b, odds ratio=0.19, p=0.006). The maximum concentration in any center was significantly less likely to occur in a kitchen than in other locations (Table 3b, odds ratio=0.180, p=0.027). However, no other features of the centers or fixtures were 11

significantly associated with having more than 1 µg/L of Pb, possibly because the occurrence of detectable Pb was common (63% of centers). In addition, there was no significant difference among water utilities. Table 3a. Risk of Pb > 15 µg/L at any water point in a childcare center using logistic regression estimates of potential risk factors. Variable (n=85) Odds Ratio 95% Confidence Interval p Value Distance to Water Treatment Plant <3.1 miles Reference Reference Reference >3.1-6.8 miles 0.18 0.0298-1.08 0.055 >6.8 miles 0.38 0.0762-2.16 0.252 Center Type Dedicated childcare center or school Reference Reference Reference Home 0.12 0.0136-0.626 0.023 Water Point Location Bathroom Reference Reference Reference Classroom 0.14 0.0190-0.941 0.048 Kitchen 0.20 0.0168-1.31 0.143 Outside 2.23 0.306-18.3 0.432

Table 3b. Risk of Pb > 1 µg/L at any water point in a childcare center using logistic regression estimates of potential risk factors. Variable (n=86)

Odds Ratio

95% Confidence Interval

p Value

Reference

Reference

Reference

0.194

0.0543-0.594

0.006

Reference

Reference

Reference

Classroom

0.738

0.172-2.85

0.667

Kitchen

0.180

0.0354-0.765

0.027

Outside

3.66

0.658-29.6

0.165

Facility Type Dedicated childcare center or school Home Water Point Location Bathroom

3.3 Risk Factors Influencing Pb Concentrations at Individual Taps Only a few features of individual water points or childcare centers were significant predictors of the Pb concentration at any individual tap within a center in the multi-level regression model (Table 4). Water Pb concentrations were 5.33 µg/L higher in samples from hoses, compared to samples from other types of water points (p<0.01). Samples from taps in staff rooms were 3.11 µg/L higher than samples from other locations (p=0.047), possibly due to lower water usage and greater stagnation periods. Water points in buildings owned by the childcare center, on average, had

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Pb concentrations that were 1.20 µg/L lower than samples from rented buildings (p<0.01). Pb concentrations were 4.41 µg/L higher in samples from newer buildings (constructed after 2014) that were relatively far (>6.8 miles) from the water treatment plant, although this difference did not quite reach statistical significance (p=0.055). No other characteristic of the centers or water points was significantly associated with measured Pb concentrations. Variability of Pb concentrations was much higher among individual water points (standard deviation=5.59 µg/L, Table 1) than variability between public water system concentrations (standard deviation=0.350) or childcare center concentrations (standard deviation=0.496), as shown by the variance components in Table 4. Table 4. Associations between childcare center and tap characteristics and Pb in individual water points. Variable (n=1,266) Coefficient Lower CI Upper CI p Water Point Location Bathroom Reference NA NA NA Classroom -0.46 -1.31 0.38 0.22 Common area -0.80 -2.67 1.07 0.28 Kitchen 0.41 -0.66 1.49 0.30 Outside -0.20 -3.34 2.93 0.40 Staff room 3.11 0.17 6.05 0.05 Fixture Type Cooler Reference NA NA NA Filter -0.34 -2.91 2.23 0.39 Fountain 0.22 -2.14 2.57 0.39 Hose 5.33 1.67 8.99 0.01 Ice maker -0.75 -8.85 7.36 0.39 Pitcher -0.48 -4.68 3.73 0.39 Refillable bottles -1.61 -8.39 5.17 0.36 Sink 0.71 -1.24 2.66 0.31 Center Ownership Rent Reference NA NA NA Own -1.20 -2.04 -0.35 0.01 Center Type Dedicated childcare center or school Reference NA NA NA Home -0.60 -1.80 0.59 0.24 Building Age Built before 1988 Reference NA NA Built 1988-2014 -0.25 -1.60 1.10 0.37 Built after 2014 -2.53 -5.66 0.59 0.11 Distance from Water Treatment Plant Short dista Reference NA NA NA Medium distb 0.14 -1.18 1.47 0.39 Long distc -0.54 -2.76 1.68 0.36 Distance from Water Treatment Plant x Building Age Medium distb x 1988-2014 -1.36 -3.25 0.53 0.15 Long distc x 1988-2014 0.62 -1.91 3.15 0.36 Medium distb x after 2014 2.18 -1.77 6.12 0.22 Long distc x after 2014 4.41 0.06 8.76 0.06 Variance Components Public water system concentration(ν00k) 0.350

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0.496 Center concentration (δ0jk) Water point (εijk) 5.59 NOTE: Coefficients are from the multi-level regression model. aShort distance: <3.1 miles from water treatment plant. bMedium distance: >3.1-6.8 miles from water treatment plant. cLong distance: >6.8 miles from water treatment plant. a,b,cCenters were binned in these groupings to include the effective date, rather than the regulatory rulemaking date, for the “1986 Pb pipe ban” (1988), and 2011 amendments (2014).

3.4 Model Comparison

Figure 2. (a) Bayesian network model showing variables associated with the risk that the maximum Pb concentration in a childcare center will exceed 15 µg/L (left). (b) Bayesian network model showing variables associated with the risk that the maximum Pb concentration in a childcare center will exceed 1 µg/L (right).

Risk of any center exceeding 15 µg/L. With improved ability to handle interactions and nonlinear relationships, the Bayesian network model (Figure 2a; Tables S3; Appendix B) uncovered additional associations between the risk of Pb above 15 µg/L and features of the childcare centers compared to the regression model presented in Table 3a. Similar to the logistic regression, the network model included distance from the water treatment plant, center type, and water point location as risk factors. However, the network also included building age, building ownership (owned versus leased), and fixture type (Figure 2a; Table S3). As in the logistic regression model, the public water system in the Bayesian network model was not associated with the risk of Pb occurrence above 15 µg/L. Risk of any center exceeding 1 µg/L. In identifying risk factors associated with a center exceeding 1 µg/L in at least one drinking water sample, results from the Bayesian network model were similar to those of the logistic regression, with facility type and sample collection location significantly associated with a childcare center having any drinking water sample with more than 1 µg/L of Pb (Figure 2b; Appendix C; Table S4). In addition, the Bayesian network model

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identified fixture type as significantly associated with Pb occurrence above 1 µg/L. Again, water utility was not a significant predictor of Pb occurrence above 1 µg/L in the Bayesian network model. Risks Based on Childcare Center Characteristics. The first Bayesian network (Figure 2a) identified a nonlinear relationship between distance to the treatment plant and the risk of Pb above 15 µg/dL. In this network, risks were highest at childcare centers either less than 3.5 or more than 15.5 miles from the water treatment plant (Table S5). Similarly, the effect of building age was nonlinear, with buildings constructed between 1964 and 2010 at lower risk than those built earlier or later (Table S5). Childcare centers in individual homes had lower risks of Pb above 15 µg/L (Table S5) or 1 µg/L (Table S6) compared to dedicated childcare centers or schools (Table S5). Whether the center is owned or leased also influenced the risk of Pb above 15 µg/L (Table S5, although this association was only marginally significant (p=0.097; Table S3); leased facilities had higher risk (26% chance of elevated Pb) compared to facilities that the center owns (10% risk). The Bayesian network analysis also identified potentially important interactions among childcare center characteristics influencing the risk of elevated Pb, as shown by the edges between variables in Figures 2a-b. For example, although the risk of elevated Pb was generally lower in home-based centers than others, risks were higher in rented home-based centers (Table S5). Similarly, the type of center and water point location also interacted. For example, samples from kitchen sinks at home-based centers had 0.070% risk of elevated lead, compared to 6.7% in sinks at dedicated childcare centers. Risk Based on Water Point Type. When considering the types of water points at which Pb concentrations exceeded 15 µg/L, the probability of elevated Pb was highest in samples from outdoor locations (38.5%), followed by bathrooms (21.1%), classrooms (9.41%), and kitchens (9.14%). Among fixture types, the risk of elevated Pb was highest for hoses (71.7%), followed by sinks (12.7%), coolers (1.22%), and water sources with filters (0.62%). Although these variables were retained in both of the final Bayesian network models (with p values <0.2), these associations did not reach statistical significance (Tables S3 and S4).

3.5 Municipal Water in the Study Area None of the water treatment plants included in the study area identified Pb at their detection limit of 3 µg/L during testing prior to distribution to water customers (Table S2). All utilities completed the testing required under the Lead and Copper Rule every three years and the average Pb at the tap was below the detection limit of 3 µg/L. A total of 503 homes were tested in the study area between 2017 and 2018. The sample collection and testing protocol was not publicly available

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for comparison. During the water treatment process at the plants, each utility implemented corrosion control methods including adding orthophosphate, pH stabilization, and/or mineral content optimization. The phosphate is intended to form a protective coating inside pipes and fixtures to control corrosion in the public water system. The water chemistry post-treatment typically had a pH ranging from 7.3 to 8.9 and alkalinity ranging from 24 to 27.5 mg/L. Moderately alkaline waters (40 to 70 mg/L) with a 7.0 to 8.2 pH are not usually corrosive. Water with a pH below 6.5 or above 7.5 can be corrosive, especially if alkalinity is lower (below 40 mg/L).51,52 In study samples at the tap, there was little variation in measured water Pb concentrations by utility in the childcare center study results by public water system (Figure 3). Among all possible pairs of utilities, only samples from Raleigh and Durham different significantly, with the mean from Raleigh samples significantly higher than the mean of samples from Durham (Tukey’s HSD test, 2.29 µg/L vs. 0.788 µg/L, p<0.05).

Figure 3. Pb concentrations measured at childcare centers by public water supply. th

th

th

th

Solid line: median; box limits: 25 and 75 percentiles; notches: 1.5 times the 25 and 75 percentile distance.

4.0 DISCUSSION 4.1 Pb Occurrence in Childcare Drinking Water Our study found that the water source at the treatment plant was not a risk factor. Public water system reports also indicate that the public water utilities serving childcare centers in the study had similar source water, corrosion control, and water chemistry. Despite compliance by water utilities within the study area with Lead and Copper Rule requirements, however, we identified detectable Pb at the tap in at least one first draw sample in 97% of the participating centers, and one

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in six participating centers contained a water point exceeding EPA’s treatment-based action level of 15 µg/L.21,26 The sampling and laboratory analysis protocols for the Lead and Copper Rule vary from 3T guidance (e.g., 1 liter bottles are used; testing may not be first draw, and laboratory detection limits are higher), which may account for the difference in findings. Additionally, the number of samples and building types samples under the Lead and Copper Rule vary. The widespread detection of Pb along with a high degree of variability in Pb concentrations across centers and at water points within the same center suggest that all taps or water points used for drinking and cooking should be tested for Pb. North Carolina childcare centers on well water complying with the US Safe Drinking Water Act currently test only one location per center, as do utilities complying the Lead and Copper Rule testing for a subset of customers. Furthermore, taps or water points not intended for consumption should have formal designations (e.g., handwashing only) to exclude them from testing. Staff and students should also be aware of which locations are designated for drinking and cooking, with staff monitoring children who may incidentally ingest non-designated water sources such as bathroom taps (e.g., water bottle filling) and hoses (e.g., during outdoor play). Our study identified several center-specific risk factors for Pb in water as well, including building age, distance from the water treatment plant, whether the facility was home-based or a dedicated center or school, and whether the building was owned or leased. It is well-known that buildings pre-dating Pb plumbing regulations are at increased risk for Pb in drinking water. Our study identified that buildings built before 1988 or after 2014 were at increased risk of Pb in at least one water point above 15 µg/L, however. The higher risks in the newer buildings, compared to those of intermediate age (1988-2014), could be related to potential leaching from newer “Pb-free” faucet fixtures.53,54,55 We also found a nonlinear relationship between distance from the water treatment plant and Pb risk, with higher risks close to or distant from the treatment plant. These differences could have arisen from changes in water chemistry within the water distribution system. The dissolution of PbO2 to soluble Pb(II) species is greater with higher concentrations of monochloramine disinfectants commonly used by water utilities, and disinfectant concentrations are expected to be higher closer to water treatment plants.52,56-59 Meanwhile, the increased risk of Pb at distant points in the distribution system could result from the increased contact time with water pipes. Pb occurrence was lower in home-based childcare centers compared to dedicated centers or schools, and center-owned rather than rented buildings, potentially because of differences in

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building size, maintenance, or other factors. Further evaluation to understand the causes of variability of Pb occurrence in drinking water across childcare center types is warranted.

4.2 Comparison to Prior Peer-Reviewed Studies To our knowledge, only two other peer-reviewed studies of Pb in water in North American childcare centers have been conducted. Consistent with a prior Canadian childcare center study, we found extremely high variability in Pb concentrations among water taps in any given center — much higher than the variability in concentrations between centers or between public water systems. Canadian researchers assembled data on tap water Pb in 8,530 large buildings, including 4,010 elementary schools or childcare centers, in four Canadian provinces collected as part of regulatory water testing campaigns.23,24 They reported median and 90th percentile Pb concentrations of 1.8 and 11 µg/L, respectively, in childcare centers and elementary schools combined. As in our study, the Canadian study found wide variability (by factors of 10-2,000) in Pb concentrations from one tap to the next within the same building. In another study in Kansas, 56 primary schools or preschools were analyzed for tap water Pb in 2008-09, with a median and mean detectable level of 3.35 µg/L and 6.16 µg/L, respectively, and a maximum value of 27.2 µg/L.23 By comparison, the median and 90th percentile concentrations (0.28 and 2.0 µg/L, respectively) in our study were lower, and our maximum concentration (121 µg/L) is in between those found in the Kansas and Canadian study. There are many potential contributing factors to the lower concentrations we observed in our samples, including water collection protocols, laboratory testing methodologies, municipal source water and treatment protocols, and infrastructure differences. The Canadian and Kansas studies focused on large buildings and schools along with preschools, respectively. Our study included primarily home-based and dedicated childcare centers and schools with Head Start preKindergarten programs. Prior research suggests that Pb concentrations can be more variable in large buildings than in smaller ones due to the high volume of piping and low water usage, leading to longer stagnation times and higher probability of Pb-bearing components somewhere in the building.23 Indeed, our multi-level regression found that school samples had a higher mean concentration than those from home-based or dedicated childcare centers, although this difference did not reach statistical significance. Similarly, our Bayesian network model found that home-based childcare models were significantly less likely to contain a water point with elevated Pb than dedicated childcare centers or schools.

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4.3 Comparison to Regulatory-Based Pb Testing We also compared the two types of regulatory-based Pb testing in North Carolina against our study scope and results. In total, 102 childcare centers on wells in North Carolina were tested for Pb in drinking water between 2007 and 2017 in accordance with US Safe Drinking Water Act requirements, with only one sample collected per center over the ten-year period. Data were provided by the North Carolina Department of Health and Human Services. Despite a limited sampling scope and frequency, along with an unknown sampling protocol, 11 centers exceeded the 15 µg/L EPA treatment-based action level (9.2%), which suggests that Pb occurrence in childcare centers on well water in North Carolina is also of concern. Additionally, a review of public utility testing within the study area under the federal Lead and Copper Rule did not identify Pb in drinking water at selected households above their reporting limit of 3 µg/L in any samples (Table S2). The scale of testing is extremely small compared to the overall population (303 houses tested in two years compared to a population of 1.5 million on municipal water in our study area) and homes rather than large buildings, dedicated childcare centers, or schools are typically tested. Sample bottle sizes are different (250 mL versus 1 L for regulatory testing), thus if the primary lead source is a fixture or fountain, lead concentrations may be lower in regulatory testing.21 Additionally, the laboratory detection limit for Pb in drinking water for utilities in the study area is typically 3 µg/L rather than 0.1 µg/L, which is 30 times higher and less likely to identify low levels of Pb occurrence. Regulatory testing also does not require the 3T protocol and it is unclear whether a similarly rigorous protocol was followed.

4.4 Limitations While we identified the occurrence of Pb in childcare centers and pinpointed several centerspecific and individual water point risk factors, additional research is needed to more fully understand and address the occurrence of Pb in drinking water at childcare centers and schools as a contributor to early childhood Pb exposure. Our study approach included training childcare administrators as citizen scientists to empower childcare centers on how to complete water testing, ease logistical and financial burdens of completing first-draw samples early in the morning by offsite professional staff, and educate childcare center staff on clean water habits. While the benefits of this approach are clear, a limitation includes possible variation from the study protocol as different citizen scientists collected their own samples. Additional study limitations are as follows.

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Water Sample Collection Protocol. Our study protocol is intended to understand the concentration of Pb in drinking water during the greatest stagnation period typical for the center – a Monday morning for most dedicated childcare centers and elementary schools, and any weekday morning for home-based childcare. Fluctuation in Pb levels in drinking water throughout the day were not considered. While first draw samples are the technique recommended for initial sampling by EPA, it is possible in certain cases that first draw samples may underestimate the concentration of Pb in water that may be present.18 In some cases, piping or plumbing not present within the volume of water captured during a first draw sample is the primary Pb source. In cases where elevated Pb is present, EPA’s 3T guidance recommends completing additional sampling that flushes samples before water collection. However, if the first draw sample does not identify elevated Pb, and a follow-up flush sample is not collected, it is possible that Pb in water further down the outlet will be missed by the current testing protocol. Risk Mitigation. Recommendations on no-cost and low-cost solutions were provided to study participants to allow childcare centers to quickly and feasibly take action. Nevertheless, verifying the effectiveness of risk mitigation recommendations was not within the study scope. Nocost solutions include designating “clean” tested taps for drinking and cooking, placing designated use signs at all taps, using only cold water, cleaning the faucet regularly, empowering staff, students, and parents to understand how to practice clean water habits, and communicating with local health departments and utilities. Flushing water before use or after stagnation is also a common mitigation recommendation with no capital cost, though it does increase the water bill. Low-cost solutions include installing and maintain water filters, fountains, and coolers certified to remove lead (NSF/ANSI 53 label), replacing faucet fixtures to new stainless steel fixtures, fixing clogs, and using lead-free products for drinking and eating. We also recommended immediately stopping use at taps with Pb detected above 15 µg/L and using another “clean” tap or alternative water until risk mitigation is completed. Pb Service Line Replacement. The US is in the midst of an infrastructure crisis that will require significant financial and technical investment to ameliorate. Our survey of the enrolled centers in this study indicated that most childcare administrators are not aware of the type of piping they have, whether it contains Pb, and whether their taps have ever been tested for Pb. Centers would need a plumber or similar professional to provide information on piping type. While our citizen science approach does not permanently solve the problem of Pb in piping and plumbing, it allows childcare centers to identify and potentially mitigate the problem of exposure to Pb in

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drinking water with no- or low-cost solutions. For more information on risk mitigation recommendations provided in the study and their potential limitations or need for further research, reference Appendix D.

4.5 Future Research Needs The recent US state and local regulations related to Pb testing in childcare centers along with schools were passed in 2016 or later in all but one state, and current peer-reviewed data on the occurrence of Pb in tap water in most schools is unavailable to our knowledge. Evaluating the testing protocols and occurrence of Pb in school children from elementary grades onward is also an important research focus, as older children are also adversely affected by Pb exposure. In New Jersey, where testing is now mandated in schools; 79% of school districts had one or more outlets above 15 µg/L.60 Future research characterizing the complete exposome for all children from infants through high school in childcare, schools, home, and outdoor play is needed to concurrently advance additional efforts to eliminate childhood exposure to Pb. Quantifying the likely increase in blood lead levels by children exposed to lead in drinking and cooking water while in childcare would be useful. If resources are available, sampling events should become routine (at least every three years), and flushed samples could be taken after first-draw samples as an additional precaution, if feasible, to further characterize variability in Pb in drinking and cooking water sources. Other sampling protocols aside from EPA’s 3T guidance have been researched to identify what water sampling most closely mirrors real exposure to Pb in drinking water.61 Sequential drinking water sampling could be used to help identify specific Pb sources and Pb service lines in cases where the source of Pb is unclear and risk mitigation is ineffective.62 Childcare centers on public water supplies were the focus of our study, as those on well water are required to test for Pb under the US Safe Drinking Water Act. As testing for centers on wells is limited however, future studies using this testing approach would be beneficial, including sampling all drinking and cooking taps, following 3T guidance with a modified stagnation period of eight to 72 hours, and training administrators as citizen scientists. Additional research evaluating the effect of variable municipal water chemistry and distribution systems on Pb occurrence in drinking water at childcare centers would solidify understanding of the risk factors associated with Pb occurrence. The nonlinear risk of greater Pb close to the drinking water treatment plant along with distant points in the distribution system also

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necessitates further study to evaluate whether higher disinfectant concentrations close to the plant and additional contact time further from the plant cause an increase in Pb occurrence in drinking water at the tap. Notably, Pb concentrations in filtered samples in our study did not differ significantly from unfiltered sink and water fountain samples, possibly because some filters were not certified to remove Pb or were not maintained properly. In most cases, filters used at centers were countertop pitchers or in select cases, filtered water coolers. Future evaluation on the types of filters in use and maintenance is needed to ensure that the filters purchased and used for Pb removal in drinking water at childcare centers are initially effective and continue removing Pb with appropriate maintenance.42 For more information on risk mitigation recommendations provided in the study and their potential limitations or need for further research, reference Appendix D.

5.0 CONCLUSIONS This study was designed to demonstrate a Pb in water testing protocol, estimate Pb prevalence, and determine risk factors associated with the occurrence of Pb in drinking water at childcare centers. Results show that children attending North Carolina, US childcare centers with detectable Pb in drinking water. Furthermore, Pb concentrations are highly variable from tap to tap, which indicate the importance of testing every tap used for drinking or cooking at all childcare centers. We demonstrate that a community-based Pb testing, communication, and mitigation strategy using childcare administrators as citizen scientists can be feasibly and successfully implemented. The piloted protocol could be readily scaled up to support widespread water testing, risk communication, and risk mitigation in childcare centers. Identifying and addressing Pb in drinking water is a critical step in preventing early childhood exposure to Pb, advancing the potential for positive educational outcomes, and improving overall wellbeing for children throughout the US.

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ACKNOWLEDGEMENTS The authors acknowledge the following key RTI staff for their invaluable contributions to the project: Linda Andrews (database development), Breda Munoz (statistical analysis), Katherine Woodward (study design, educational flyers, enrollment), Ellen Thomas (risk communication, site visits), Kibri Everett (site visits, geographic information systems), Maggie O’Neill (geographic information systems), Abby Czeskleba (graphic design), Amal Essader (site visits), Paige Presler-Jur (site visits), Laurie Stella (sample preparation and shipping), Andrea McWilliams (laboratory analysis and quality control), and Frank Weber (laboratory analysis). The authors are appreciative of the feedback and support from local public utilities, health departments, universities, and nonprofits. Most importantly, we would like to recognize center and school administrators for becoming citizen scientists in the effort to provide children in childcare with access to safe drinking water.

AUTHOR CREDIT STATEMENT Jennifer Hoponick Redmon: Conceptualization, Methodology, Visualization, Investigation, Data Curation, Formal Analysis, Writing – Original Draft, Writing – Review and Editing, Project Administration, Supervision, Funding Acquisition. Keith E. Levine: Methodology, Investigation, Resources, Writing – Review and Editing, Supervision, Funding Acquisition. Anna M. Aceituno: Methodology, Visualization, Project Administration, Data Curation, Writing – Review and Editing. Kristin Litzenberger: Validation, Project Administration, Data Curation, Writing – Review and Editing. Jacqueline MacDonald Gibson: Software, Formal Analysis, Writing – Original Draft, Writing – Review and Editing.

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HIGHLIGHTS •

We piloted a lead (Pb) testing strategy in North Carolina, US childcare centers using citizen scientists and mail-out test kits.

•

Pb was detected above the American Academy of Pediatrics Reference Level of 1 ug/L in 63% of centers, and 97% of centers had at least one tap with detectable Pb (0.1 ug/L).

•

One in six centers contained Pb above 15 ug/L in at least one tap.

•

Variability of Pb concentrations was high among individual taps within centers, suggesting every tap used for drinking or cooking should be tested for Pb.

•

Routine water testing, risk communication, and risk mitigation is warranted in early childhood education settings to prevent childhood exposure to Pb in drinking water.

FUNDING SOURCES AND CONFLICT OF INTEREST STATEMENT The authors would like to thank RTI International for providing internal research and development grants to conduct the Clean Water for Carolina Kids pilot study, and for hosting Dr. Jackie MacDonald Gibson as an RTI Scholar during 2017-2018. This study did not include research on human subjects or experimental animals. The authors declare no conflicts of interest.