Community drinking water data on the National Environmental Public Health Tracking Network: a surveillance summary of data from 2000 to 2010

Problem/ConditionThe places in which persons live, work, and play can contribute to the development of adverse health outcomes. Understanding the differences in risk factors in various environments can help to explain differences in the occurrence of these outcomes and can be used to develop public health programs, interventions, and policies. Efforts to characterize urban and rural differences have largely focused on social and demographic characteristics. A paucity of national standardized environmental data has hindered efforts to characterize differences in the physical aspects of urban and rural areas, such as air and water quality.Reporting Period2008–2012 for air quality and 2010–2015 for water quality.Description of SystemSince 2002, CDC’s National Environmental Public Health Tracking Program has collaborated with federal, state, and local partners to gather standardized environmental data by creating national data standards, collecting available data, and disseminating data to be used in developing public health actions. The National Environmental Public Health Tracking Network (i.e., the tracking network) collects data provided by national, state, and local partners and includes 21 health outcomes, exposures, and environmental hazards. To assess environmental factors that affect health, CDC analyzed three air-quality measures from the tracking network for all counties in the contiguous United States during 2008–2012 and one water-quality measure for 26 states during 2010–2015. The three air-quality measures include 1) total number of days with fine particulate matter (PM2.5) levels greater than the U.S. Environmental Protection Agency’s (EPA’s) National Ambient Air Quality Standards (NAAQS) for 24-hour average PM2.5 (PM2.5 days); 2) mean annual average ambient concentrations of PM2.5 in micrograms per cubic meter (mean PM2.5); and 3) total number of days with maximum 8-hour average ozone concentrations greater than the NAAQS (ozone days). The water-quality measure compared the annual mean concentration for a community water system (CWS) to the maximum contaminant level (MCL) defined by EPA for 10 contaminants: arsenic, atrazine, di(2-ethylhexyl) phthalate (DEHP), haloacetic acids (HAA5), nitrate, perchloroethene (PCE), radium, trichloroethene (TCE), total trihalomethanes (TTHM), and uranium. Findings are presented by urban-rural classification scheme: four metropolitan (large central metropolitan, large fringe metropolitan, medium metropolitan, and small metropolitan) and two nonmetropolitan (micropolitan and noncore) categories. Regression modeling was used to determine whether differences in the measures by urban-rural categories were statistically significant.ResultsPatterns for all three air-quality measures suggest that air quality improves as areas become more rural (or less urban). The mean total number of ozone days decreased from 47.54 days in large central metropolitan counties to 3.81 days in noncore counties, whereas the mean total number of PM2.5 days decreased from 11.21 in large central metropolitan counties to 0.95 in noncore counties. The mean average annual PM2.5 concentration decreased from 11.15 μg/m3 in large central metropolitan counties to 8.87 μg/m3 in noncore counties. Patterns for the water-quality measure suggest that water quality improves as areas become more urban (or less rural). Overall, 7% of CWSs reported at least one annual mean concentration greater than the MCL for all 10 contaminants combined. The percentage increased from 5.4% in large central metropolitan counties to 10% in noncore counties, a difference that was significant, adjusting for U.S. region, CWS size, water source, and potential spatial correlation. Similar results were found for two disinfection by-products, HAA5 and TTHM. Arsenic was the only other contaminant with a significant result. Medium metropolitan counties had 3.1% of CWSs reporting at least one annual mean greater than the MCL, compared with 2.4% in large central counties.InterpretationNoncore (rural) counties experienced fewer unhealthy air-quality days than large central metropolitan counties, likely because of fewer air pollution sources in the noncore counties. All categories of counties had a mean annual average PM2.5 concentration lower than the EPA standard. Among all CWSs analyzed, the number reporting one or more annual mean contaminant concentrations greater the MCL was small. The water-quality measure suggests that water quality worsens as counties become more rural, in regards to all contaminants combined and for the two disinfection by-products individually. Although significant differences were found for the water-quality measure, the odds ratios were very small, making it difficult to determine whether these differences have a meaningful effect on public health. These differences might be a result of variations in water treatment practices in rural versus urban counties.Public Health ActionUnderstanding the differences between rural and urban areas in air and water quality can help public health departments to identify, monitor, and prioritize potential environmental public health concerns and opportunities for action. These findings suggest a continued need to develop more geographically targeted, evidence-based interventions to prevent morbidity and mortality associated with poor air and water quality.

BACKGROUND AND AIM: The US Environmental Protection Agency (EPA) sets maximum contaminant levels (MCLs) for 9 metals/metalloids in public drinking water systems. Beyond arsenic, no nationwide exposure estimates for public drinking water currently exist for these contaminants. Our objective was to estimate exposure to metals in community water systems (CWSs) across the US, to determine if sociodemographic or regional inequalities in these exposures exist, and to identify patterns of exposure for these metals as a mixture. METHODS: We evaluated routine compliance monitoring records for antimony, barium, beryllium, cadmium, chromium, mercury, selenium, thallium, and uranium collected from 2006-2011 (2000-2011 for uranium) by the US EPA in support of the Third Six Year Review for 37,915 CWSs. We focused our analysis on barium, chromium, selenium, and uranium (as arsenic has been reported previously and other metals were mostly undetected), comparing the mean contaminant concentration and the percent of CWSs with MCL excedances across subgroups (US region, sociodemographic county-cluster, size of population served, source water type, and correctional facilities). We evaluated patterns in metal exposure profiles via hierarchical cluster analysis, which also included published CWS arsenic estimates. RESULTS:The percentage of CWSs exceeding the MCL was highest for uranium (3.1% MCL of 30 µg/L, nationwide mean 4.37 µg/L), but lower than previously reported arsenic (2.6%). 75th, 95th percentiles for uranium, chromium, barium, and selenium concentrations were highest for CWSs serving {Semi-Urban, Hispanic} communities, small CWSs, CWSs reliant on groundwater, and those located in the Southwest, similar to previous CWS arsenic findings. Hierarchical cluster analysis revealed four clusters, including an arsenic-uranium-selenium cluster. CONCLUSIONS:{Semi-Urban, Hispanic} communities experience higher average concentrations of metal contaminants, including uranium and arsenic, in public drinking water. Uranium is an under-recognized contaminant in CWSs. Cluster analyses revealed that arsenic and uranium may co-occur in groundwater sources serving CWSs. KEYWORDS: exposure, environmental justice, environmental disparities, water quality

Disinfectant byproducts (DBPs) haloacetic acids (HAA5) and total trihalomethanes (TTHM) used in community water systems (CWS) are potential bladder and colorectal carcinogens. Studies neglect to account for how exposures may differ within counties based on population served (PS) by CWS, which provides estimates of individual exposure. CWS concentration data for HAA5 and TTHM with PS were obtained for eight US states. These were summed to create additive DBP exposure and aggregated to the county-level to construct three cumulative county-level HAA5, TTHM, and additive DBP exposure metrics: unadjusted for PS; controlled for PS (as a covariate); and accounted for PS (concentration multiplied by proportion of PS by county population). Poisson regressions estimated incidence rate ratios (IRR) and 95% confidence intervals for associations between colorectal and bladder cancer and DBP, HAA5, and TTHM exposure tertiles, adjusting for potential confounders. For unadjusted DBP tertiles (<331 parts per billion (ppb), 331-732 ppb, >732ppb), the IRRs for colorectal cancer were 1.27 (1.22,1.32) and 1.58 (1.53,1.64) for tertiles 2-3, compared to <331 ppb, the lowest exposure category. For DBP tertiles controlled by PS, the IRRs were 1.27 (1.22,1.32) and 1.59 (1.54,1.65) for tertiles 2-3, compared to <331 ppb. After accounting for PS (<178 ppb, 178-502 ppb, >502 ppb), the IRRs were 0.92 (0.88,0.96) and 1.46 (1.41,1.51) for tertiles 2-3, compared to <178 ppb. Associations between colorectal cancer and HAA5 and TTHM tertiles were similar to the DBP tertiles. Associations between bladder cancer and HAA5, TTHM, and DBP tertiles were also similar to colorectal. Differing measures of PS by CWS in measured drinking water HAA5, TTHM, and DBP concentrations resulted in positive but varied associations to colorectal and bladder cancer. Thus, PS may need to be considered when developing drinking water exposure measures. This abstract does not reflect EPA policy.

Thyroid cancer incidence has been steadily increasing over the past decade in the United States (US). A discussion exists regarding the potential contribution of exposure to endocrine-disrupting chemicals, encompassing certain per- and poly-fluoroalkyl substances (PFASs). This ecological study evaluated the potential correlation between PFAS levels in drinking water and thyroid cancer incidence in the US. Data on age-adjusted thyroid cancer incidence rate (per 100,000 persons) by county were obtained from the Centers for Disease Control and Prevention (CDC) for US counties with available data in 2015–2019. Data on PFAS concentrations in the drinking water of selected community water systems (CWSs) were obtained from the CDC National Environmental Public Health Tracking Network in 2013–2015. The correlation between PFASs in CWSs and thyroid cancer incidence was calculated using Spearman correlation. A statistically significant correlation was found between perfluorooctanoic acid (PFOA) (r = 0.031; p = 0.043), perfluorononanoic acid (PFNA) (r = 0.058; p ≤ 0.001), and thyroid cancer incidence. The results suggest a potential link between certain PFAS exposures and thyroid cancer risk. However, due to the nature of an ecological study, no conclusions can be drawn at the individual level or causality. More research is needed, particularly on an individual level to allow for more detailed exposure assessment.

Many studies neglect to account for variation in population served by community water systems (CWSs) when aggregating CWS-level contaminant concentrations to county level. In an ecological epidemiologic analysis, we explored two methods-unweighted and weighted (proportion of CWS population served by county population)-to account for population served by CWS in association between arsenic and three cancers to determine the impact of population served on aggregated measures of exposure. CWS arsenic concentration data for 19 states were obtained from Centers for Disease Control and Prevention (CDC) National Environmental Public Health Tracking Network for 2000-10, aggregated to county level, and linked to county-level cancer data for 2011-5 from National Cancer Institute and CDC State Cancer Profiles. Negative binomial regression models estimated adjusted risk ratios (aRR) and 95% confidence intervals (CI) between county-level bladder, colorectal, and kidney cancers and quartiles of aggregated cumulative county-level arsenic concentration (ppb-years). We observed positive associations between the highest quartileof exposure, compared to the lowest, ofaggregated cumulative county-level arsenic concentration (ppb-year) for bladder [weighted aRR: 1.89(1.53, 2.35)], colorectal [1.64(1.33, 2.01)], and kidney [1.69(1.37, 2.09)] cancers. We observed stronger associations utilizing the weighted exposure assessment method. However, inferences from this study are limited due to the ecologic nature of the analyses and different analytic study designs are needed to assess the utility that the weighted by CWS population served metric has for exposure assessment. Weighting by CWS population served accounts for some potential exposure assignment error in epidemiologic analysis.

Sociodemographic inequalities in uranium and other metals in community water systems across the USA, 2006–11: a cross-sectional study

Background: Very little is known about the quality of drinking water in US correctional facilities (e.g. detention centers, prisons, jails, etc.), which disproportionately detain people of color. The current Environmental Protection Agency’s maximum contaminant level (MCL) for arsenic in public drinking water is 10 µg/L. We estimated drinking water arsenic concentrations in US correctional facilities to determine if incarcerated persons remain at risk for chronic, elevated water arsenic exposure relative to the non-incarcerated US population.Methods: We obtained 230,158 arsenic monitoring records for 37,098 community water systems (CWSs) from the Environmental Protection Agency’s Third Six Year Review of Contaminant Occurrence dataset (covering 2006-2011). We compared six-year average arsenic concentrations in all CWSs versus CWSs exclusively serving correctional facilities. We separately evaluated the Southwestern US (where groundwater arsenic concentrations are relatively high) versus non-Southwestern US.Results: Average six-year water arsenic concentrations were higher for CWSs exclusively serving correctional facilities in the Southwest (6.41 µg/L, 95% CI 3.48, 9.34) compared to all other Southwestern CWSs (3.11 µg/L, 95% CI 2.97, 3.24) and to other CWSs across the rest of the US (1.39 µg/L, 95% CI 1.35, 1.42). Compared to other US CWSs and to other Southwestern CWSs, correctional facility CWSs in the Southwest were more likely to report six-year arsenic averages exceeding 10 µg/L (1.6%, 5.8%, and 26.1% of systems, respectively).Conclusions: CWSs exclusively serving correctional facilities in the Southwestern US reported average water arsenic concentrations twice as high as those reported by all other CWSs in the Southwest, and more than a quarter reported six-year averages exceeding the EPA’s regulatory MCL. Strict enforcement of the EPA’s drinking water regulations and a comprehensive review of other drinking water contaminants in CWSs serving correctional facilities is necessary to protect the health and human rights of all incarcerated persons in the US.

Arsenic in drinking water poses a threat to public health world-wide. In March 2001, the EPA revised the maximum contaminant level (MCL) for arsenic in drinking water downward from 50 µg/L to 10 µg/L and required all U.S. small community water systems (CWSs) and non-community water systems (NCWSs) to comply by 23 January 2006. Much of the financial burden associated with complying with and maintaining this new drinking water MCL was shouldered by local community governments. For example, the Walker River Paiute Tribe operated a CWS on the Walker River Paiute Indian Reservation that needed upgrading to meet the new arsenic MCL. In collaboration with the Walker River Paiute Tribe, we conducted a study to assess whether reducing the arsenic concentration in drinking water to meet the new MCL reduced the arsenic body burden in local community members who drank the water. Installing a drinking water treatment to remove arsenic dramatically reduced both the drinking water concentrations (to below the current EPA MCL of 10 µg/L) and the community members’ urinary concentrations of total As, AsIII, and AsV within a week of its full implementation. Additional assistance to small water systems to sustain new drinking water treatments may be warranted.

BackgroundPollutants including metals/metalloids, nitrate, disinfection byproducts, and volatile organic compounds contaminate federally regulated community water systems (CWS) and unregulated domestic wells across the United States. Exposures and associated health effects, particularly at levels below regulatory limits, are understudied.ObjectiveWe described drinking water sources and exposures for the California Teachers Study (CTS), a prospective cohort of female California teachers and administrators.MethodsParticipants’ geocoded addresses at enrollment (1995–1996) were linked to CWS service area boundaries and monitoring data (N = 115,206, 92%); we computed average (1990–2015) concentrations of arsenic, uranium, nitrate, gross alpha (GA), five haloacetic acids (HAA5), total trihalomethanes (TTHM), trichloroethylene (TCE), and tetrachloroethylene (PCE). We used generalized linear regression to estimate geometric mean ratios of CWS exposures across demographic subgroups and neighborhood characteristics. Self-reported drinking water source and consumption at follow-up (2017–2019) were also described.ResultsMedians (interquartile ranges) of average concentrations of all contaminants were below regulatory limits: arsenic: 1.03 (0.54,1.71) µg/L, uranium: 3.48 (1.01,6.18) µg/L, GA: 2.21 (1.32,3.67) pCi/L, nitrate: 0.54 (0.20,1.97) mg/L, HAA5: 8.67 (2.98,14.70) µg/L, and TTHM: 12.86 (4.58,21.95) µg/L. Among those who lived within a CWS boundary and self-reported drinking water information (2017–2019), approximately 74% self-reported their water source as municipal, 15% bottled, 2% private well, 4% other, and 5% did not know/missing. Spatially linked water source was largely consistent with self-reported source at follow-up (2017–2019). Relative to non-Hispanic white participants, average arsenic, uranium, GA, and nitrate concentrations were higher for Black, Hispanic and Native American participants. Relative to participants living in census block groups in the lowest socioeconomic status (SES) quartile, participants in higher SES quartiles had lower arsenic/uranium/GA/nitrate, and higher HAA5/TTHM. Non-metropolitan participants had higher arsenic/uranium/nitrate, and metropolitan participants had higher HAA5/TTHM.ImpactThough average water contaminant levels were mostly below regulatory limits in this large cohort of California women, we observed heterogeneity in exposures across sociodemographic subgroups and neighborhood characteristics. These data will be used to support future assessments of drinking water exposures and disease risk.

BackgroundFew studies of environmental justice examine inequities in drinking water contamination. Those studies that have done so usually analyze either disparities in exposure/harm or inequitable implementation of environmental policies. The US EPA’s 2001 Revised Arsenic Rule, which tightened the drinking water standard for arsenic from 50 μg/L to 10 μg/L, offers an opportunity to analyze both aspects of environmental justice.MethodsWe hypothesized that Community Water Systems (CWSs) serving a higher proportion of minority residents or residents of lower socioeconomic status (SES) have higher drinking water arsenic levels and higher odds of non-compliance with the revised standard. Using water quality sampling data for arsenic and maximum contaminant level (MCL) violation data for 464 CWSs actively operating from 2005–2007 in California’s San Joaquin Valley we ran bivariate tests and linear regression models.ResultsHigher home ownership rate was associated with lower arsenic levels (ß-coefficient= −0.27 μg As/L, 95% (CI), -0.5, -0.05). This relationship was stronger in smaller systems (ß-coefficient= −0.43, CI, -0.84, -0.03). CWSs with higher rates of homeownership had lower odds of receiving an MCL violation (OR, 0.33; 95% CI, 0.16, 0.67); those serving higher percentages of minorities had higher odds (OR, 2.6; 95% CI, 1.2, 5.4) of an MCL violation.ConclusionsWe found that higher arsenic levels and higher odds of receiving an MCL violation were most common in CWSs serving predominantly socio-economically disadvantaged communities. Our findings suggest that communities with greater proportions of low SES residents not only face disproportionate arsenic exposures, but unequal MCL compliance challenges.

Ground Water Systems’ Progress in Meeting National Drinking Water Goals

The Centers for Disease Control and Prevention's National Environmental Public Health Tracking Program is leading an initiative to build a National Environmental Public Health Tracking Network (Tracking Network) that integrates data into a network of standardized electronic data to provide valid scientific information on environmental exposures and adverse health conditions, as well as spatial and temporal relations between them. The Web-based Tracking Network is designed for different audiences including government, the academic community, and the public. A primary goal of the Tracking Network is to allow the exploration of data on health effects, environments, and demographics. The wide variety of data types along with stratifications present a complex problem when developing system functionality to query and display disparate data simultaneously in a comparable way using charts, tables, and maps. While the ability to query and display data that span across geographies and multiple time periods for a single type of data has been the main feature set of the Tracking Network, allowing the same for multiple data types is needed to enable users to explore trends and possible associations among health and environmental data. As a first step, a multidisciplinary team was formed to address complex issues related to developing the ability to view multiple measures on the Tracking Network. The team then iterated through steps involving requirements gathering, the segmentation of the requirements into functional areas, submission of proposals to address those functional areas, and finally evaluation of the proposals to address functional areas. Adding the ability to view multiple measures is an important step to improve Tracking Network users' exploration of the environmental health status of their communities. With this capability, public health practitioners and other users can formulate hypotheses, analyze trends, and explore possible relationships across a wide variety of environmental and health information.

Parks and recreation departments and public health organizations both work to improve the well-being of their communities. Measuring residential proximity to parks could be a specific area of shared interest, given that proximity to parks is needed for walking access, and the use of parks is, in turn, associated with many physical, social, and mental health benefits. The CDC's publicly available National Environmental Public Health Tracking Network (NEPHTN) Access to Parks Indicator (API) focuses on one major component of access, residential proximity to parks. The API uses a commercial parks database and U.S. Census data to estimate the number and percentage of individuals in the U.S. that live within a half-mile of a park boundary, a measure commonly used to represent park proximity. The API is calculated at the state and county levels and is available for all states and counties in the U.S. Using estimates from the API, we examined the distribution of residential proximity to parks by geography and race/ethnicity. Additionally, we evaluated differences in park proximity by rural/urban status of counties. In 2010, 39% of the total U.S. population lived within a half-mile of a park. This percentage varied widely between states, ranging from 9% in West Virginia to 67% in Hawaii and 88% in the District of Columbia (DC). Park proximity was lowest among non-Hispanic whites (34.2%) and highest among individuals belonging to the non-Hispanic other race category (52.0%). Metropolitan counties had the highest percentage of residents living within a half-mile of a park (43.3%); the percentage was lower in non-metropolitan counties adjacent to a metropolitan county (15.0%) and non-metropolitan counties not adjacent to a metropolitan county (18.5%). Park proximity was higher in metropolitan counties with a larger population size and in non-metropolitan counties with a higher degree of urbanization. The NEPHTN Access to Parks Indicator provides an opportunity to understand park proximity in counties and states throughout the U.S., including identifying disparities that may exist between population subgroups and comparing geographic areas. Parks and recreational professionals can use this information to compare their county or state to other geographic areas and, in combination with local data on parks within their jurisdiction, inform decisions to improve the distribution of parks and the well-being of their communities.

Background and Aim Many studies show marginalized communities are disproportionately exposed to air pollution. However, relatively few studies have considered water quality disparities, including exposures to per- and polyfluoroalkyl substances (PFAS). We evaluated whether Community Water Systems (CWS) serving greater proportions of minority and low-income individuals had higher likelihoods of detecting PFAS and exceeding Maximum Contaminant Levels (MCL) using recent statewide drinking water monitoring data. Methods We compiled drinking water PFAS concentration data from 11 states with statewide monitoring data and ancillary data on sociodemographics, CWS characteristics, active PFAS treatment, and PFAS sources. We examined associations between PFAS concentrations in drinking water and sociodemographics at various spatial units for 4,698 CWS (serving 62.2 million people) using multivariate logistic regressions. Results CWS serving 20.8 million people (33%) had detectable concentrations (>5 ng/L) of at least one of five PFAS and those serving 16 million people (26%) exceeded the lowest state-level MCL for several PFAS. CWS with detectable PFAS levels and MCL exceedances served greater proportions of Hispanic and Black residents than those with PFAS levels below detection and without exceedances. At the county-level, a percentage point increase in the proportion of Hispanic residents served by a CWS was associated with a 4-6% increase in the odds of detecting PFAS. Results for state-level relationships were more mixed, although CWS in five of the 11 states had increased odds of detecting several PFAS for CWS serving counties with greater proportions of Hispanic residents. Conclusions Our findings suggest that CWS serving some communities with greater proportions of Hispanic and non-Hispanic Black residents have increased likelihood of detecting PFAS, including detection at levels above regulatory thresholds. These disparities are concerning and warrant consideration when planning remediation strategies and treatment for sites contaminated with PFAS. Keywords Community water systems, Environmental justice, Drinking water, Anthropogenic compounds, Disparities

Background:Disinfection byproducts (DBPs) and N-nitroso compounds (NOC), formed endogenously after nitrate ingestion, are suspected endometrial carcinogens, but epidemiological studies are limited.Objectives:We investigated the relationship of these exposures with endometrial cancer risk in a large prospective cohort.Methods:Among postmenopausal women in the Iowa Women’s Health Study cohort, we evaluated two major classes of DBPs, total trihalomethanes (TTHM) and five haloacetic acids (HAA5), and nitrate-nitrogen () in public water supplies (PWS) in relation to incident primary endometrial cancer (1986–2014). For women using their PWS at enrollment (; ), we computed historical averages of annual concentrations; exposures were categorized into quantiles and when possible percentile. We also computed years of PWS use above one-half the U.S. maximum contaminant level (; TTHM; HAA5; ). Dietary nitrate/nitrite intakes were estimated from a food frequency questionnaire. We estimated hazard ratios (HR) and 95% confidence intervals (CI) via Cox models adjusted for age, endometrial cancer risk factors [e.g., body mass index, hormone replacement therapy (HRT)], and mutually adjusted for . We evaluated associations for low-grade () vs. high-grade () type I tumors. We assessed interactions between exposures and endometrial cancer risk factors and dietary factors influencing NOC formation.Results:Higher average concentrations of DBPs (95th percentile: TTHM , HAA5 ) were associated with endometrial cancer risk (TTHM: , 95% CI: 1.41, 3.40; HAA5: , 95% CI: 1.19, 2.83; ). Associations were similarly observed for women greater than median years of PWS use with levels , in comparison with zero years (TTHM: , 95% CI: 1.18, 2.21; HAA5: , 95% CI: 1.31, 2.62). Associations with DBPs appeared stronger for low-grade tumors (TTHM: , 95% CI: 1.17, 3.83; ) than for high-grade tumors (TTHM: , 95% CI: 0.80, 2.44; ), but differences were not statistically significant (). Associations with TTHM were stronger among ever HRT users than non-HRT users (). We observed no associations with in drinking water or diet.Discussion:We report novel associations between the highest DBP levels and endometrial cancer for our Iowa cohort that warrant future evaluation. https://doi.org/10.1289/EHP10207