Early life lead exposure from private well water increases juvenile delinquency risk among US teens.

Early life exposure to environmental lead (Pb) has been linked to decreased IQ, behavior problems, lower lifetime earnings, and increased criminal activity. Beginning in the 1970s, limits on Pb in paint, gasoline, food cans, and regulated water utilities sharply curtailed US environmental Pb exposure. Nonetheless, hundreds of thousands of US children remain at risk. This study reports on how unregulated private well water is an underrecognized Pb exposure source that is associated with an increased risk of teenage juvenile delinquency. We build a longitudinal dataset linking blood Pb measurements for 13,580 children under age 6 to their drinking water source, individual- and neighborhood-level demographics, and reported juvenile delinquency records. We estimate how early life Pb exposure from private well water influences reported delinquency. On average, children in homes with unregulated private wells had 11% higher blood Pb than those with community water service. This higher blood Pb was significantly associated with reported delinquency. Compared to children with community water service, those relying on private wells had a 21% (95% CI: 5 to 40%) higher risk of being reported for any delinquency and a 38% (95% CI: 10 to 73%) increased risk of being reported for serious delinquency after age 14. These results suggest that there could be substantial but as-yet-unrecognized social benefits from intervention programs to prevent children's exposure to Pb from private wells, on which 13% of the US population relies.

Association between drinking water quality and mental health and the modifying role of diet: a prospective cohort study.

BACKGROUND: Environmental factors play an important role in developing mental disorders. This study aimed to investigate the associations of metal and nonmetal elements in drinking water with the risk of depression and anxiety and to assess whether diets modulate these associations. METHODS: We conducted a prospective cohort study including 24,285 participants free from depression and anxiety from the Yinzhou Cohort study in the 2016-2021 period. The exposures were measured by multiplying metal and nonmetal element concentrations in local pipeline terminal tap water samples and total daily drinking water intakes. Cox regression models adjusted for multi-level covariates were used to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (95%CIs). RESULTS: During an average follow-up period of 4.72 and 4.68 years, 773 and 1334 cases of depression and anxiety were identified, respectively. A 1 standard deviation (SD) increase in manganese exposure reduced the incidence of depression by 8% (HR 0.92, 95%CI 0.88 to 0.97). In contrast, with a 1 SD increase in copper and cadmium exposure, the incidence of depression increased by 6% (HR 1.06, 95%CI 1.01 to 1.11) and 8% (HR 1.08, 95%CI 1.00 to 1.17), respectively. The incidence of anxiety increased by 39% (HR 1.39, 95%CI 1.20 to 1.62), 33% (HR 1.33, 95%CI 1.03 to 1.71), and 14% (HR 1.14, 95%CI 1.03 to 1.25) respectively for a 1 SD increase in manganese, iron, and selenium exposure. Diets have a moderating effect on the associations of metal and nonmetal elements with the risk of anxiety. Stronger associations were observed in older, low-income groups and low-education groups. CONCLUSIONS: We found significant associations between exposure to metal and nonmetal elements and depression and anxiety. Diets regulated the associations to some extent.

Persistence and free chlorine disinfection of human coronaviruses and their surrogates in water.

The coronavirus disease 2019 pandemic illustrates the importance of understanding the behavior and control of human pathogenic viruses in the environment. Exposure via water (drinking, bathing, and recreation) is a known route of transmission of viruses to humans, but the literature is relatively void of studies on the persistence of many viruses, especially coronaviruses, in water and their susceptibility to chlorine disinfection. To fill that knowledge gap, we evaluated the persistence and free chlorine disinfection of human coronavirus OC43 (HCoV-OC43) and its surrogates, murine hepatitis virus (MHV) and porcine transmissible gastroenteritis virus (TGEV), in drinking water and laboratory buffer using cell culture methods. The decay rate constants of human coronavirus and its surrogates in water varied, depending on virus and water matrix. In drinking water without disinfectant addition, MHV showed the largest decay rate constant (estimate ± standard error, 2.25 ± 0.09 day-1) followed by HCoV-OC43 (0.99 ± 0.12 day-1) and TGEV (0.65 ± 0.06 day-1), while in phosphate buffer without disinfectant addition, HCoV-OC43 (0.51 ± 0.10 day-1) had a larger decay rate constant than MHV (0.28 ± 0.03 day-1) and TGEV (0.24 ± 0.02 day-1). Upon free chlorine disinfection, the inactivation rates of coronaviruses were independent of free chlorine concentration and were not affected by water matrix, though they still varied between viruses. TGEV showed the highest susceptibility to free chlorine disinfection with the inactivation rate constant of 113.50 ± 7.50 mg-1 min-1 L, followed by MHV (81.33 ± 4.90 mg-1 min-1 L) and HCoV-OC43 (59.42 ± 4.41 mg-1 min-1 L). IMPORTANCE: This study addresses an important knowledge gap on enveloped virus persistence and disinfection in water. Results have immediate practical applications for shaping evidence-based water policies, particularly in the development of disinfection strategies for pathogenic virus control.

Source-to-tap investigation of the occurrence of nontuberculous mycobacteria in a full-scale chloraminated drinking water system.

Nontuberculous mycobacteria (NTM) in drinking water are a significant public health concern. However, an incomplete understanding of the factors that influence the occurrence of NTM in drinking water limits our ability to characterize risk and prevent infection. This study sought to evaluate the influence of season and water treatment, distribution, and stagnation on NTM in drinking water. Samples were collected source-to-tap in a full-scale, chloraminated drinking water system approximately monthly from December 2019 to November 2020. NTM were characterized using culture-dependent (plate culture with matrix-assisted laser desorption ionization-time-of-flight mass spectrometry [MALDI-TOF MS] isolate analysis) and culture-independent methods (quantitative PCR and genome-resolved metagenomics). Sampling locations included source waters, three locations within the treatment plant, and five buildings receiving water from the distribution system. Building plumbing samples consisted of first draw, 5-min flush, and full flush cold-water samples. As the study took place during the COVID-19 pandemic, the influence of reduced water usage in three of the five buildings was also investigated. The highest NTM densities source-to-tap were found in the summer first draw building water samples (107 gene copies/L), which also had the lowest monochloramine concentrations. Flushing was found to be effective for reducing NTM and restoring disinfectant residuals, though flush times necessary to improve water quality varied by building. Clinically relevant NTM species, including Mycobacterium avium, were recovered via plate culture, with increased occurrence observed in buildings with higher water age. Four of five NTM metagenome-assembled genomes were identified to the species level and matched identified isolates.IMPORTANCENTM infections are increasing in prevalence, difficult to treat, and associated with high morbidity and mortality rates. Our lack of understanding of the factors that influence NTM occurrence in drinking water limits our ability to prevent infections, accurately characterize risk, and focus remediation efforts. In this study, we comprehensively evaluated NTM in a full-scale drinking water system, showing that various steps in treatment and distribution influence NTM presence. Stagnant building water contained the highest NTM densities source-to-tap and was associated with low disinfectant residuals. We illustrated the differences in NTM detection and characterization obtained from culture-based and culture-independent methods, highlighting the complementarity between these approaches. We demonstrated that focusing NTM mitigation efforts in building plumbing systems, which have the highest NTM densities source-to-tap, has potential for immediate positive effects. We also identified steps during treatment that increase NTM levels, which provides beneficial information for utilities seeking to reduce NTM in finished water.

Impact of operational conditions on drinking water biofilm dynamics and coliform invasion potential.

Biofilms within drinking water distribution systems serve as a habitat for drinking water microorganisms. However, biofilms can negatively impact drinking water quality by causing water discoloration and deterioration and can be a reservoir for unwanted microorganisms. In this study, we investigated whether indicator organisms for drinking water quality, such as coliforms, can settle in mature drinking water biofilms. Therefore, a biofilm monitor consisting of glass rings was used to grow and sample drinking water biofilms. Two mature drinking water biofilms were characterized by flow cytometry, ATP measurements, confocal laser scanning microscopy, and 16S rRNA sequencing. Biofilms developed under treated chlorinated surface water supply exhibited lower cell densities in comparison with biofilms resulting from treated groundwater. Overall, the phenotypic as well as the genotypic characteristics were significantly different between both biofilms. In addition, the response of the biofilm microbiome and possible biofilm detachment after minor water quality changes were investigated. Limited changes in pH and free chlorine addition, to simulate operational changes that are relevant for practice, were evaluated. It was shown that both biofilms remained resilient. Finally, mature biofilms were prone to invasion of the coliform, Serratia fonticola. After spiking low concentrations (i.e., ±100 cells/100 mL) of the coliform to the corresponding bulk water samples, the coliforms were able to attach and get established within the mature biofilms. These outcomes emphasize the need for continued research on biofilm detachment and its implications for water contamination in distribution networks. IMPORTANCE: The revelation that even low concentrations of coliforms can infiltrate into mature drinking water biofilms highlights a potential public health concern. Nowadays, the measurement of coliform bacteria is used as an indicator for fecal contamination and to control the effectiveness of disinfection processes and the cleanliness and integrity of distribution systems. In Flanders (Belgium), 533 out of 18,840 measurements exceeded the established norm for the coliform indicator parameter in 2021; however, the source of microbial contamination is mostly unknown. Here, we showed that mature biofilms, are susceptible to invasion of Serratia fonticola. These findings emphasize the importance of understanding and managing biofilms in drinking water distribution systems, not only for their potential to influence water quality, but also for their role in harboring and potentially disseminating pathogens. Further research into biofilm detachment, long-term responses to operational changes, and pathogen persistence within biofilms is crucial to inform strategies for safeguarding drinking water quality.

Quantitative microbial risk assessment for ingestion of antibiotic resistance genes from private wells contaminated by human and livestock fecal sources.

We used quantitative microbial risk assessment to estimate ingestion risk for intI1, erm(B), sul1, tet(A), tet(W), and tet(X) in private wells contaminated by human and/or livestock feces. Genes were quantified with five human-specific and six bovine-specific microbial source-tracking (MST) markers in 138 well-water samples from a rural Wisconsin county. Daily ingestion risk (probability of swallowing ≥1 gene) was based on daily water consumption and a Poisson exposure model. Calculations were stratified by MST source and soil depth over the aquifer where wells were drilled. Relative ingestion risk was estimated using wells with no MST detections and >6.1 m soil depth as a referent category. Daily ingestion risk varied from 0 to 8.8 × 10-1 by gene and fecal source (i.e., human or bovine). The estimated number of residents ingesting target genes from private wells varied from 910 (tet(A)) to 1,500 (intI1 and tet(X)) per day out of 12,000 total. Relative risk of tet(A) ingestion was significantly higher in wells with MST markers detected, including wells with ≤6.1 m soil depth contaminated by bovine markers (2.2 [90% CI: 1.1-4.7]), wells with >6.1 m soil depth contaminated by bovine markers (1.8 [1.002-3.9]), and wells with ≤6.1 m soil depth contaminated by bovine and human markers simultaneously (3.1 [1.7-6.5]). Antibiotic resistance genes (ARGs) were not necessarily present in viable microorganisms, and ingestion is not directly associated with infection. However, results illustrate relative contributions of human and livestock fecal sources to ARG exposure and highlight rural groundwater as a significant point of exposure.IMPORTANCEAntibiotic resistance is a global public health challenge with well-known environmental dimensions, but quantitative analyses of the roles played by various natural environments in transmission of antibiotic resistance are lacking, particularly for drinking water. This study assesses risk of ingestion for several antibiotic resistance genes (ARGs) and the class 1 integron gene (intI1) in drinking water from private wells in a rural area of northeast Wisconsin, United States. Results allow comparison of drinking water as an exposure route for antibiotic resistance relative to other routes like food and recreational water. They also enable a comparison of the importance of human versus livestock fecal sources in the study area. Our study demonstrates the previously unrecognized importance of untreated rural drinking water as an exposure route for antibiotic resistance and identifies bovine fecal material as an important exposure factor in the study setting.

Vibrio cholerae O1 and Escherichia coli O157:H7 from drinking water and wastewater in Addis Ababa, Ethiopia.

BACKGROUND: In Addis Ababa, Ethiopia, open ditches along innner roads in residential areas serve to convey domestic wastewater and rainwater away from residences. Contamination of drinking water by wastewater through faulty distribution lines could expose households to waterborne illnesses. This prompted the study to assess the microbiological safety of wastewater and drinking water in Addis Ababa, identify the pathogens therein, and determine their antibiotic resistance patterns. RESULTS VIBRIO CHOLERAE: O1, mainly Hikojima serotype, was isolated from 23 wastewater and 16 drinking water samples. Similarly, 19 wastewater and 10 drinking water samples yielded Escherichia coli O157:H7. V. cholerae O1 were 100% resistant to the penicillins (Amoxacillin and Ampicillin), and 51-82% were resistant to the cephalosporins. About 44% of the V. cholerae O1 isolates in this study were Extended Spectrum Beta-Lactamase (ESBL) producers. Moreover, 26% were resistant to Meropenem. Peperacillin/Tazobactam was the only effective ß-lactam antibiotic against V. cholerae O1. V. cholerae O1 isolates showed 37 different patterns of multiple resistance ranging from a minimum of three to a maximum of ten antimicrobials. Of the E. coli O157:H7 isolates, 71% were ESBL producers. About 96% were resistant to Ampicillin. Amikacin and Gentamicin were very effective against E. coli O157:H7 isolates. The isolates from wastewater and drinking water showed multiple antibiotic resistance against three to eight antibiotic drugs. CONCLUSIONS: Open ditches for wastewater conveyance along innner roads in residence areas and underground faulty municipal water distribution lines could be possible sources for V. cholerae O1 and E. coli O157:H7 infections to surrounding households and for dissemination of multiple drug resistance in humans and, potentially, the environment.

Arsenic exposure is associated with alterations to multiple red blood cell parameters among adults in rural Bangladesh.

Chronic arsenic exposures are associated with multiple hematologic disturbances, including anemia. The goal of this study was to evaluate associations between arsenic exposures and hematological parameters among men and women who are chronically exposed to elevated levels of arsenic from drinking water. Hematologic analyses were performed on blood collected from 755 participants (45% male and 54% female) in the Health Effects of Arsenic Longitudinal Study (HEALS) cohort, Bangladesh. Herein, we used linear regression models to estimate associations between red blood cell (RBC) parameters (i.e., RBC counts, hematocrit (HCT), hemoglobin (Hgb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC)) and measurements of arsenic exposure (urinary arsenic and urinary arsenic metabolites). Arsenic exposures showed trending associations with decreased RBC counts in both men and women, a positive association with MCV in males, and an inverse association with MCHC among males, but not among non-smoking females. Among men, those who smoked had stronger associations between arsenic exposures and MCHC than non-smoking males. Collectively, our results show that arsenic exposures affect multiple RBC parameters and highlight potentially important sex differences in arsenic-induced hematotoxicity.

Arsenic in drinking water and lung cancer: A systematic review of 35 years of evidence.

The association between higher arsenic concentrations in drinking water and lung cancer is well-established. However, the risk associated with lower levels of arsenic exposure remains uncertain. This systematic review and meta-analysis summarizes the evidence on the relationship between exposure to arsenic in drinking water and lung cancer outcomes as measured over a broad range of exposures, including lower levels. A total of 51 studies were included in the review and 15 met criteria for inclusion in meta-analysis. Risk estimates for lung cancer incidence and mortality were pooled and analyzed separately using Bayesian hierarchical random-effects models with a Gaussian observation submodel for log(Risk), computed using the "brms" R package. For lung cancer incidence, the predicted posterior mean relative risks (RRs) at arsenic concentrations of 10, 50 and 150 µg/L were 1.11 (0.86-1.43), 1.67 (1.27-2.17) and 2.21 (1.61-3.02), respectively, with posterior probabilities of 79%, 100% and 100%, respectively, for the RRs to be >1. The posterior mean mortality ratios at 20, 50 and 150 µg/L were 1.22 (0.83-1.78), 2.10 (1.62-2.71) and 2.41 (1.88-3.08), respectively, with posterior probabilities being above 80%. In addition to observing the dose-response relationship, these findings demonstrate that individuals exposed to low to moderate levels of arsenic (<150 µg/L) were at an elevated risk of developing or dying from lung cancer. Given the widespread exposure to lower levels of arsenic, there is an urgent need for vigilance and potential revisions to regulatory guidelines to protect people from the cancer risks associated with arsenic exposure.

Employing a Toxic Aging Coin approach to assess hexavalent chromium (Cr[VI])-induced neurotoxic effects on behavior: Heads for age differences.

We are facing a rapidly growing geriatric population (65+) that will live for multiple decades and are challenged with environmental pollution far exceeding that of previous generations. Consequently, we currently have a poor understanding of how environmental pollution will impact geriatric health distinctly from younger populations. Few toxicology studies have considered age differences with geriatric individuals. Critically, all top ten most prevalent age-related diseases are linked to metal exposures. Hexavalent chromium [Cr(VI)] is a metal of major environmental health concern that can induce aging phenotypes and neurotoxicity. However, there are many knowledge gaps for Cr(VI) neurotoxicity, including how Cr(VI) impacts behavior. To address this, we exposed male rats across three ages (3-, 7-, and 18-months old) to Cr(VI) in drinking water (0, 0.05, 0.1 mg/L) for 90 days. These levels reflect the maximum contaminant levels determined by the World Health Organization (WHO) and the U.S. Environmental Protection Agency (US EPA). Here, we report how these Cr(VI) drinking water levels impacted rat behaviors using a battery of behavior tests, including grip strength, open field assay, elevated plus maze, Y-maze, and 3-chamber assay. We observed adult rats were the most affected age group and memory assays (spatial and social) exhibited the most significant effects. Critically, the significant effects were surprising as rats should be particularly resistant to these Cr(VI) drinking water levels due to the adjustments applied in risk assessment from rodent studies to human safety, and because rats endogenously synthesize vitamin C in their livers (vitamin C is a primary reducer of Cr[VI] to Cr[III]). Our results emphasize the need to broaden the scope of toxicology research to consider multiple life stages and suggest the current regulations for Cr(VI) in drinking water need to be revisited.

Systematic review of studies on exposure to arsenic in drinking water and cognitive and neurobehavioral effects.

An association between exposure to arsenic (As) and neurologic and behavioral effects has been reported in some studies, but no systematic review is available of the evidence linking As in drinking water and neurobehavioral effects after consideration of study quality and potential confounding, with focus on low-level circumstances of exposure. We conducted a systematic review and reported it in compliance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, through a search of the databases PubMed, Web of Science, Scopus, and Embase. We included in the review the studies reporting results based on exposure from drinking water in humans. Endpoints were heterogeneous across studies, so we classified them into eight broad domains and developed an ad-hoc system to evaluate their methodological quality, based on three tiers. It was not possible to conduct meta-analysis because of the heterogeneity in exposure assessment and in the definition and assessment of outcomes. The search identified 18,518 articles. After elimination of duplicates and irrelevant articles, we retained 106 articles which reported results on As exposure and neurobehavioral effects, of which 22 reported risk estimates from exposure in drinking water (six among adults and 16 among children). None of the studies was conducted blindly. Among the studies in adults, two, which were conducted in highly exposed populations, were classified as high quality. These two studies were broadly consistent in reporting an association between exposure to As and decline in cognitive function; however, they provide no evidence of an association for exposure below 75 µg/L. The four lower-quality studies were based on populations with low exposure; these studies reported associations with inconsistent outcomes, few of which remained statistically significant after adjustment for multiple comparisons. Among the five high-quality studies of children, one reported an association between As in drinking water and intellectual function, whereas none of the other studies reported an association with different neurobehavioral indicators, after adjusting for potential confounders and multiple comparisons. Out of seven intermediate-quality studies, three reported an association with cognitive function or other outcomes; but sources of bias were not adequately controlled. The remaining studies were negative. The four low-quality studies did not contribute to the overall evidence because of methodological limitations. Our assessment of the available literature showed a lack of evidence for a causal association between exposure to As in drinking water and neurobehavioral effects. To clarify whether such an association exists, further studies prospectively evaluating changes in both the concentration of As in drinking water during the life course, and neurobehavioral outcomes, as well as appropriately controlling for potential confounders, are needed.

Systematic review of epidemiological and toxicological evidence on health effects of fluoride in drinking water.

INTRODUCTION: Fluoride is a naturally occurring substance that is also added to drinking water, dental hygiene products, and food supplements for preventing dental caries. Concerns have been raised about several other potential health risks of fluoride. OBJECTIVE: To conduct a robust synthesis of evidence regarding human health risks due to exposure to fluoride in drinking water, and to develop a point of departure (POD) for setting a health-based value (HBV) for fluoride in drinking water. METHODS: A systematic review of evidence published since recent reviews of human, animal, and in vitro data was carried out. Bradford Hill considerations were used to weigh the evidence for causality. Several key studies were considered for deriving PODs. RESULTS: The current review identified 89 human studies, 199 animal studies, and 10 major in vitro reviews. The weight of evidence on 39 health endpoints was presented. In addition to dental fluorosis, evidence was considered strong for reduction in IQ scores in children, moderate for thyroid dysfunction, weak for kidney dysfunction, and limited for sex hormone disruptions. CONCLUSION: The current review identified moderate dental fluorosis and reduction in IQ scores in children as the most relevant endpoints for establishing an HBV for fluoride in drinking water. PODs were derived for these two endpoints, although there is still some uncertainty in the causal weight of evidence for causality for reducing IQ scores in children and considerable uncertainty in the derivation of its POD. Given our evaluation of the overall weight of evidence, moderate dental fluorosis is suggested as the key endpoint until more evidence is accumulated on possible reduction of IQ scores effects. A POD of 1.56 mg fluoride/L for moderate dental fluorosis may be preferred as a starting point for setting an HBV for fluoride in drinking water to protect against moderate and severe dental fluorosis. Although outside the scope of the current review, precautionary concerns for potential neurodevelopmental cognitive effects may warrant special consideration in the derivation of the HBV for fluoride in drinking water.

Effect of household pipe materials on formation and chlorine resistance of the early-stage biofilm: various interspecific interactions exhibited by the same microbial biofilm in different pipe materials.

Microbial community biofilm exists in the household drinking water system and would pose threat to water quality. This paper explored biofilm formation and chlorination resistance of ten dual-species biofilms in three typical household pipes (stainless steel (SS), polypropylene random (PPR), and copper), and investigated the role of interspecific interaction. Biofilm biomass was lowest in copper pipes and highest in PPR pipes. A synergistic or neutralistic relationship between bacteria was evident in most biofilms formed in SS pipes, whereas four groups displayed a competitive relationship in biofilms formed in copper pipe. Chlorine resistance of biofilms was better in SS pipes and worse in copper pipes. It may be helped by interspecific relationships, but was more dependent on bacteria and resistance mechanisms such as more stable extracellular polymeric substance. The corrosion sites may also protect bacteria from chlorination. The findings provide useful insights for microbial control strategies in household drinking water systems.

Effect of Community Water Service on Lead in Drinking Water in an Environmental Justice Community.

Multiple recent studies have found elevated lead (Pb) concentrations in tap water in U.S. homes relying on unregulated private wells. The main Pb source is dissolution from household plumbing, fixtures, and well components. Here, we leverage a natural experiment and citizen science approach to evaluate how extending community water service to an environmental justice community relying on private wells affects Pb in household water. We analyzed Pb in 260 first-draw kitchen tap water samples collected by individual homeowners over a 5-month period in residences that did and did not connect to the community system. Before the community water system was extended, 25% of homes had Pb > 15 µg/L (the U.S. regulatory action level for community water systems) in first-draw water samples. Pb was significantly correlated with nickel (ρ = 0.61), zinc (ρ = 0.50), and copper (ρ = 0.40), suggesting that corrosion of brass fittings and fixtures is the main Pb source. Among homes that connected to the community system, Pb decreased rapidly and was sustained at levels well below 15 µg/L over the study period. Overall, connecting to the municipal water supply was associated with a 92.5% decrease in first-draw tap water Pb.

Prioritization and Risk Ranking of Regulated and Unregulated Chemicals in US Drinking Water.

Drinking water constituents were compared using more than six million measurements (USEPA data) to prioritize and risk-rank regulated and unregulated chemicals and classes of chemicals. Hazard indexes were utilized for hazard- and risk-based chemicals, along with observed (nondetects = 0) and censored (nondetects = method detection limit/2) data methods. Chemicals (n = 139) were risk-ranked based on population exposed, resulting in the highest rankings for inorganic compounds (IOCs) and disinfection byproducts (DBPs), followed by semivolatile organic compounds (SOCs), nonvolatile organic compounds (NVOCs), and volatile organic compounds (VOCs) for observed data. The top 50 risk-ranked chemicals included 15 that were unregulated, with at least one chemical from each chemical class (chromium-6 [#1, IOC], chlorate and NDMA [#11 and 12, DBP], 1,4-dioxane [#25, SOC], PFOS, PFOA, PFHxS [#42, 44, and 49, NVOC], and 1,2,3-trichloropropane [#48, VOC]). These results suggest that numerous unregulated chemicals are of higher exposure risk or hazard in US drinking water than many regulated chemicals. These methods could be applied following each Unregulated Contaminant Monitoring Rule (UCMR) data collection phase and compared to retrospective data that highlight what chemicals potentially pose the highest exposure risk or hazard among US drinking water, which could inform regulators, utilities, and researchers alike.

Improving Private Well Testing Programs: Experimental Evidence from Iowa.

Approximately 23 million U.S. households rely on private wells for drinking water. This study first summarizes drinking water behaviors and perceptions from a large-scale survey of households that rely on private wells in Iowa. Few households test as frequently as recommended by public health experts. Around 40% of households do not regularly test, treat, or avoid their drinking water, suggesting pollution exposure may be widespread among this population. Next, we utilize a randomized control trial to study how nitrate test strips and information about a free, comprehensive water quality testing program influence households' behaviors and perceptions. The intervention significantly increased testing, including high-quality follow-up testing, but had limited statistically detectable impacts on other behaviors and perceptions. Households' willingness to pay for nitrate test kits and testing information exceeds program costs, suggesting that the intervention was welfare-enhancing.

Estimating Lithium Concentrations in Groundwater Used as Drinking Water for the Conterminous United States.

Lithium (Li) concentrations in drinking-water supplies are not regulated in the United States; however, Li is included in the 2022 U.S. Environmental Protection Agency list of unregulated contaminants for monitoring by public water systems. Li is used pharmaceutically to treat bipolar disorder, and studies have linked its occurrence in drinking water to human-health outcomes. An extreme gradient boosting model was developed to estimate geogenic Li in drinking-water supply wells throughout the conterminous United States. The model was trained using Li measurements from ∼13,500 wells and predictor variables related to its natural occurrence in groundwater. The model predicts the probability of Li in four concentration classifications, ≤4 µg/L, >4 to ≤10 µg/L, >10 to ≤30 µg/L, and >30 µg/L. Model predictions were evaluated using wells held out from model training and with new data and have an accuracy of 47-65%. Important predictor variables include average annual precipitation, well depth, and soil geochemistry. Model predictions were mapped at a spatial resolution of 1 km2 and represent well depths associated with public- and private-supply wells. This model was developed by hydrologists and public-health researchers to estimate Li exposure from drinking water and compare to national-scale human-health data for a better understanding of dose-response to low (<30 µg/L) concentrations of Li.

Considering a Utility-Centric Framework Based on "Minimum Orthophosphate" Criteria for Mitigation of Elevated Cuprosolvency in Drinking Water.

Gaps in the United States Environmental Protection Agency (US EPA) Lead and Copper Rule (LCR) leave some consumers and their pets vulnerable to high cuprosolvency in drinking water. This study seeks to help proactive utilities who wish to mitigate cuprosolvency problems through the addition of orthophosphate corrosion inhibitors. The minimum doses of orthophosphate necessary to achieve acceptable cuprosolvency in relatively new copper pipe were estimated as a function of alkalinity via linear regressions for the 90th, 95th, and 100th percentile copper tube segments (R2 > 0.98, n = 4). Orthophosphate was very effective at reducing cuprosolvency in the short term but, in some cases, resulted in higher long-term copper concentrations than the corresponding condition without orthophosphate. Alternatives to predicting "long-term" results for copper tubes using simpler bench tests starting with fresh Cu(OH)2 solids showed promise but would require further vetting to overcome limitations such as maintaining water chemistry and orthophosphate residuals and to ensure comparability to results using copper tube.

Climate-Driven Increases in Source Water Natural Organic Matter: Implications for the Sustainability of Drinking Water Treatment.

This study presents an updated analysis spanning over two decades (1999-2023) of climate, water quality, and operational data from two drinking water facilities in Atlantic Canada that previously experienced gradual increases in the natural organic matter (NOM) concentration and brownification. The goal was to assess the impact of recent extreme weather events on acute NOM concentration increases and drinking water treatment processes. In 2023, a dry spring combined with a warm and wet summer caused NOM in the water supplies to increase by >67% (as measured by color). To mitigate increased NOM concentration, the alum dose nearly doubled in 2023 compared to that in 2022. Disinfection byproducts were elevated following the event but remained within the compliance levels. From 1999 to 2023, the two plants responded to gradual climate change impacts and brownification, with alum dose increases of between 4.1 and 8.3 times. Equivalent CO2 emissions were estimated for alum usage, which increased by 3 to 7-fold in 2023 compared to when the plants were commissioned decades prior. The plants were not only adversely impacted by climate change but also contributed to the global CO2 burden. Thus, a paradigm shift toward sustainable alternatives for NOM removal is required in the water sector, and climate change adaptation and mitigation principles are urgently needed.

Comprehensive Toxicological Assessment of Halobenzoquinones in Drinking Water at Environmentally Relevant Concentration.

Halobenzoquinones (HBQs), an emerging unregulated category of disinfection byproduct (DBP) in drinking water, have aroused an increasing concern over their potential health risks. However, the chronic toxicity of HBQs at environmentally relevant concentrations remains largely unknown. Here, the occurrence and concentrations of 13 HBQs in drinking water from a northern megacity in China were examined using ultrahigh performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UHPLC-MS/MS). Four HBQs, including 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ), 2,6-dibromo-1,4-benzoquinone (2,6-DBBQ), 2,3,6-trichloro-1,4-benzoquinone (TriCBQ), and 2,5-dibromo-1,4-benzoquinone (2,5-DBBQ), were detected beyond 50% occurrence frequency and at median concentrations from 4 to 50 ng/L. The chronic toxicity of these four HBQs to normal human colon and liver cells (FHC and THLE-2) was investigated at these concentrations. After 90 days of exposure, 2,5-DBBQ and 2,6-DCBQ induced the highest levels of oxidative stress and deoxyribonucleic acid (DNA) damage in colon and liver cells, respectively. Moreover, 2,5-DBBQ and 2,6-DCBQ were also found to induce epithelial-mesenchymal transition (EMT) in normal human liver cells via the extracellular signal regulated kinase (ERK) signaling pathway. Importantly, heating to 100 °C (boiling) was found to efficiently reduce the levels of these four HBQs in drinking water. These results suggested that environmentally relevant concentrations of HBQs could induce cytotoxicity and genotoxicity in normal human cells, and boiling is a highly efficient way of detoxification for HBQs.