Tag: wellness

Integrating water quality and water quantity to diagnose the health of water metabolism systems in multi-core multi-level urban agglomerations

Author links open overlay panelYing Yang a1

, Jing Wen a1

, Meirong Su b

, Qionghong Chen cShow moreAdd to MendeleyShareCite

https://doi.org/10.1016/j.watres.2025.123899Get rights and content

Highlights

  • •The MRIO table was compiled for a multi-core multi-level urban agglomeration.
  • •A diagnostic framework was established by coupling ENA and MRIO approaches.
  • •Water quantity-water quality linkage was considered in the diagnostic framework.
  • •The IWMN was less vigorous and less organized than the QWMN.
  • •The IWMN tended slightly towards mutualism but had more negative collaborations.

Abstract

Urban agglomerations (UAs) are compelled to scrutinize the health of their water systems as the frequency of water crises increases. An urban water system’s health is closely related to metabolism processes. To date, water systems in multi-core multi-level UAs have not been analyzed using water quantity and water quality because of methodological constraints. To address this research gap, we developed an integrated water quality–water quantity model for diagnosing water metabolism systems that could process nested multi-region input-output (MRIO) tables. We coupled the MRIO tables and established two networks, an integrated water quantity–quality metabolism network (IWMN) and a water quantity metabolism network (QWMN). We tested the two networks with data from the Guangdong-Hong Kong-Macao UA and assessed four aspects of the networks’ health, namely vigor, organization, resilience, and collaboration, using ecological network analysis. We discovered that IWMN exhibited lower vigor (internal circulation 10.4 %) and organization dominated by dependency (total contribution intensity σ = -23) compared to the QWMN. Polity-driven disparities shaped the robustness distribution, while a mutualism tendency coexisted with a complex exploitation relationship (52.4 %), particularly in the core large-sized city of Hong Kong, where 58 new competitive pairs emerged. Thus, we recommend prioritizing Guangdong-Hong Kong-Macao trade optimization for high-water-content products to enhance system health.

Graphical abstract

Image, graphical abstract

Introduction

The surface water deficit experienced in 482 of the world’s largest cities is projected to reach 6.75 million tons by 2050 because of an imbalance between the water supply and the demand (Flörke et al., 2018). This trend has prompted growing interest in resource allocation and environmental protection within urban agglomerations (UAs). UAs are composed of multiple geographically adjacent cities with diverse sizes and characteristics (Fang et al., 2015). Diverse UAs with multi-core structures (classified by comprehensive urban engine functions) and multi-level systems (quantified by social indicators) face challenges due to high heterogeneity in population size and spatial resource allocation (Han et al., 2019; Chirigati, 2022; Zhao et al., 2021). Water quantity and water quality are important attributes of water resources. Changes in the water quantity caused by a lack of rainfall or heavy rainfall events affect the water quality by concentrating pollutants or diluting. Conversely, degraded water quality diminishes the availability of water resources (Li et al., 2023) and has direct effects on urban aquatic ecosystems (Liu and Yang, 2012). Therefore, to optimize water management in multi-core multi-level UAs, we need to know more about the combined effects of water quality and water quantity on the water resources.

When optimizing water management in urban areas, the water metabolism mechanism of the system should be analyzed, and key issues should be identified (Cao et al., 2021; He et al., 2020b; Liu et al., 2022). The concept of water metabolism originates from urban metabolism (Wolman, 1965), which describes water cycle processes (e.g., water input, output, and storage) driven by social activities in different cities (Wang and Chen, 2010). This concept can effectively identify hidden risks resulting from the allocation of social resources—such as population, industry and environment within UAs, thus challenging the traditional multilevel paradigm of urban water management. In assessing the health of water systems based on water metabolism mechanisms, processes analogous to those in natural ecosystems, such as vigor and collaboration (Y.J. Yang et al., 2020; Zhu et al., 2020), sustained and stable organization, and adaptability to external pressures (Yan et al., 2014), are employed. However, to date, most research has primarily focused on the efficiency of consumptive activities (Nishimura et al., 2021; Qi et al., 2021; Xu et al., 2020), while ignoring the underlying water metabolism processes.

Network methods are effective for characterizing critical resource metabolism processes (Liang et al., 2020). Ecological Network Analysis (ENA) (Hannon B, 1973) quantifies metabolic features via resource fluxes (Fath, 2004; Ulanowicz et al., 2009), offering insights into system health. For example, resource footprint circulation rates reflect node vigor; balanced control-dependency relationships enhance organizational capacity; maintaining metabolic orderliness optimizes resilience thresholds; and niche complementarity indices help analyze co-evolutionary collaboration. There is concern about the approaches used to quantitatively assess the resource flows within a network. A bottom-up approach uses industrial processes to track water flows (Vanham and Bidoglio, 2013), but a top-down approach quantitatively assesses the resource flows within a network (Feng et al., 2011). For example, input-output analysis (IOA), an accepted method for quantifying water flows in a water metabolism system, is preferred over bottom-up approaches because it can link industrial economic data to water consumption using input-output tables and produce a high-resolution view of the networked water flow transactions, helping us to address issues caused within UAs by economic trade, such as water-related resource flows, ecosystem services, and health status (Hubacek and Feng, 2016). However, our ability to carry out a comprehensive and accurate assessment of water system health within UAs is hampered by a lack of high-resolution MRIO data for multi-core multi-level UAs, which has resulted from the poor alignment of statistical standards used for trade data across cities of different levels.

To date, there is little clarity about how the combination of water quantity and water quality influences the health of water metabolism systems in UAs. Cao et al. (2021) were the first to evaluate the health of water networks using an assessment model that focused on water quantity, but excluded water quality. Adequate water quantity and sufficient water quality are essential for the sustainable use of urban water resources (Cai et al., 2023). A water footprint, which incorporates both water quantity and water quality, can be used to assess water flows (Hoekstra and Mekonnen, 2012). Various water footprints have been defined, and the blue water footprint (BWF) and grey water footprint (GWF) have been used to quantify both water quantity and water quality (Chapagain and Hoekstra, 2011; Yu et al., 2022). In previous studies, researchers have focused on either water quantity or water quality when assessing the intensity of resource transfers (Cai et al., 2023; Zhao et al., 2016) and the factors that influenced them (Cai and Guo, 2023; Guan et al., 2014). Some researchers have also simulated and evaluated the performance of metabolism systems using either water quantity or water quality as the independent metabolism medium (He et al., 2020b, 2020a; Liu et al., 2022). The conventional separation of water quantity and quality in current research paradigms makes it difficult to reveal the cascading effects of their synergistic interactions on multiscale metabolism systems, which may lead to ecological cognitive bias in system health assessments. As synergistic variables within regional metabolism system, the mechanisms underlying the interactions between water quantity and water quality remain underexplored. It is imperative to conceptualize water quantity and quality as an integrated metabolism medium and develop a corresponding theoretical framework to elucidate how their synergistic metabolic processes influence system health.

The diagnoses of water metabolism system health at the UA scale are constrained by a) a lack of MRIO tables, which hinders the accurate assessment of water flow within UAs with multi-core and multi-level cities, and b) a limited understanding of how the health of metabolism systems is influenced when water quantity and water quality are combined into a single metabolism medium. To address these issues, we proposed a method for compiling MRIO tables for multi-core multi-level UAs that resolved the methodological limitations associated with assessments of water flow. We created two networks based on MRIO and ENA, one that integrated water quantity and water quality and another for water quantity only, and assessed four attributes of the health of the two networks, namely vigor, organization, resilience, and collaboration. We then tested the method with data from the Guangdong-Hong Kong-Macao Greater Bay Area UA (GBA).

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https://www.sciencedirect.com/science/article/abs/pii/S0043135425008073?via%3Dihub

Assessing exposure and health consequences of chemicals in drinking water in the 21st Century

Journal of Exposure Science & Environmental Epidemiology volume 34, pages1–2 (2024)Cite this article

Populations worldwide are exposed to a myriad of chemicals via drinking water, yet only a handful of chemicals have been extensively evaluated with regard to human exposures and health impacts [1, 2]. Many chemicals are generally “invisible” in that they do not alter the color or odor of drinking water, and many of the associated effects are not observable for decades, making linkages between exposure and disease difficult. The articles included in the Journal of Exposure Science and Environmental Epidemiology Special Topic “Assessing Exposure and Health Consequences of Chemicals in Drinking Water in the 21st Century” cover a range of topics, including: (i) new exposure and health research for regulated and emerging chemicals, (ii) new methods and tools for assessing exposure to drinking water contaminants, (iii) issues of equity and environmental justice, (iv) drinking water issues within the context of a changing climate. This Special Topic includes articles authored by experts across multiple disciplines including environmental engineering, hydrology, exposure science, epidemiology, toxicology, climate science, and others. Many of these papers emerged from an international symposium organized by ISGlobal and Yale scientists held in Barcelona in September 2022 [3].

Regulated chemicals

Chemicals that have been the focus of environmental health research include disinfection by-products (DBPs), nitrate, and metals. Although many of these chemicals are regulated, there is concern about low-dose exposures at concentrations below standards and guidelines, and risks of health endpoints not yet studied. Kaufman et al. explore new ways to assess DBP exposure, considering concentrations and specific toxicity potential in relation to birth defects risk [4]. Long-term exposure to DBPs and nitrate is addressed by Donat-Vargas et al. in relation to chronic lymphocytic leukaemia in Spain [5]. Friedman et al. examine temporal and spatial variability of manganese concentrations in a case study in the United States (US) [6]. Hefferon et al. evaluated sociodemographic inequalities in fluoride concentrations across the US [7]. Spaur et al. evaluate the contribution of water arsenic to biomarker levels in a prospective study in the US [8].

Chemicals of emerging concern

Many emerging chemicals, such as per- and polyfluoroalkyl substances (PFAS), microplastics, and 1,4-dioxane, have drinking water as the dominant exposure pathway for many populations. Yet, these remain largely unregulated or have standards and guidelines that vary widely across states and countries. Because only small percentages of the universe of contaminants are regulated in drinking water, routine monitoring data for many chemicals of emerging concern is frequently absent or very limited. To advance understanding of drinking water exposures to PFAS, Cserbik et al. [9]. and Kotlarz et al. [10]. evaluate and compare PFAS in drinking water and blood serum samples in two different settings: an urban setting not impacted by PFAS pollution in Spain [9] and among well water users living near a fluorochemical facility in the US [10], respectively.

New methods and tools for exposure assessment

There is a need for improved tools, methods, and data to evaluate drinking water related exposures. These tools and techniques remain somewhat limited and lag behind those of other stressors (e.g., air pollution). Also, despite water contaminants occurring in mixtures, most of the evaluations (and policies and regulations) are conducted chemical by chemical, ignoring potential interactions. Schullehner et al. present case studies of three approaches of exposure assessment of drinking water quality: use of country-wide routine monitoring databases, wide-scope chemical analysis, and effect-based bioassay methods [11]. Luben et al. elaborate and compare different exposure assessment metrics to trihalomethanes in epidemiological analyses of reproductive and developmental outcomes [12]. Escher et al. present in vitro assays to evaluate biological responses of including neurotoxicity, oxidative stress, and cytotoxicity in different types of drinking water samples (tap, bottled, filtered) [13] Isaacs et al. present newly developed automated workflows to screen contaminants of concern based on toxicity and exposure potential [14]. Dorevitch et al. develop a novel method to improve detection of particulate lead spikes [15].

Issues of equity, environmental justice, and vulnerable populations

A substantial portion of the population (e.g., 20% in the United States) have private water supplies (e.g., a household domestic drinking water well), which are not subject to any federal regulatory oversight or monitoring [16]. This presents an equity issue in access to data on drinking water quality, as discussed in Levin et al. [2]. and heterogeneity in state-based policies for drinking water prevention, as discussed by Schmitt et al. [17]. Spaur et al. [8], observed that water from unregulated private wells and regulated municipal water supplies contributes substantially to overall exposures (as measured by urinary arsenic and uranium concentrations) in both rural, American Indian populations and urban, racially/ethnically diverse populations nationwide. Hefferon et al. evaluated environmental justice issues with respect to fluoride and found that 2.9 million US residents are served by public water systems with average fluoride concentrations exceeding the World Health Organization’s guidance limit [7]. Friedman et al. show that manganese in drinking water frequently exceeds current guidelines in the US, and occur at concentrations shown to be associated with adverse health outcomes, especially for vulnerable and susceptible populations like children [6].

Chemical contamination may also pose a serious threat in the developing world. Today, around 2.2 billion people – or 1 in 4 – still lack safely managed drinking water at home [18]. In most of the world, microbial contamination is the biggest challenge. Because it has been understudied, the chemical risks remain obscure [19], and regulators often require local data to take action. Praveena et al. reviews the quality of different drinking water types in Malaysia (tap water, ground water, gravity feed system) and its implications on policy, human health, management, and future research [20].

Water quality in a changing climate

There is an urgent need to anticipate and prepare for current and future challenges in a rapidly changing world. We also need to foresee new challenges to address issues of water scarcity (e.g., increasing desalination, use of treated wastewater in densely populated urban areas to meet water use demands), and aging infrastructure for many middle- and high-income countries constructed in the nineteenth and twentieth centuries. The impacts of climate change on the water cycle are direct and observable, such as more frequent droughts and floods, sea level rise, and ice/snow melt. These events will challenge drinking water quality and availability through direct and indirect mechanisms [21]. There is still very limited knowledge on how climate events will affect the quality of finished drinking water. In our special issue, Oliveras et al. conducts a new analysis on the impacts of drought and heavy rain surrogates on the quality of drinking water in Barcelona, Spain [22].

Conclusion

Chemical contamination of drinking water is widespread. Although our knowledge on chemical risks in drinking water is increasing, there are knowledge gaps that make a slow translation to public health protection. We hope this issue highlights, elevates, and motivates research on chemical exposures via drinking water.

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https://www.nature.com/articles/s41370-024-00639-0

Public trust in drinking water safety is low globally

Low confidence in water quality is associated with perceptions of public corruption

Source:Northwestern University

Summary:A new study finds more than half of adults surveyed worldwide expect to be seriously harmed by their water within the next two years. The study sought to understand public perceptions of drinking water safety. Because perceptions shape attitudes and behaviors, distrust in water quality has a negative impact on people’s health, nutrition, psychological and economic well-being — even when the water meets safety standards.Share:

    

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A new study finds more than half of adults surveyed worldwide expect to be seriously harmed by their water within the next two years. Led by global health experts at Northwestern University and the University of North Carolina at Chapel Hill, the study sought to understand public perceptions of drinking water safety.

Because perceptions shape attitudes and behaviors, distrust in water quality has a negative impact on people’s health, nutrition, psychological and economic well-being — even when the water meets safety standards.

“If we think our water is unsafe, we will avoid using it,” said Sera Young, professor of anthropology and global health at Northwestern and senior author of the new study.

“When we mistrust our tap water, we buy packaged water, which is wildly expensive and hard on the environment; drink soda or other sugar-sweetened beverages, which is hard on the teeth and the waistline; and consume highly processed prepared foods or go to restaurants to avoid cooking at home, which is less healthy and more expensive,” Young said. “Individuals exposed to unsafe water also experience greater psychological stress and are at greater risk of depression.”

Young is a Morton O. Schapiro Faculty Fellow at the Institute for Policy Research, a faculty fellow at the Paula M. Trienens Institute for Sustainability and Energy, and co-lead of the Making Water Insecurity Visible Working Group at the Buffett Institute for Global Affairs.

Using nationally representative data from 148,585 adults in 141 countries from the 2019 Lloyd’s Register Foundation World Risk Poll, the authors found a high prevalence of anticipated harm from water supply, with the highest in Zambia, the lowest in Singapore and an overall mean of 52.3%.

They also identified key characteristics of those who thought they would be harmed by their drinking water. Women, city dwellers, individuals with more education, and those struggling on their current income were more likely to anticipate being harmed by their drinking water.

The researchers found that, surprisingly, higher corruption perception index scores were the strongest predictor of anticipated harm from drinking water, more so than factors like infrastructure and Gross Domestic Product.

Further, even within countries with consistent access to basic drinking water services, doubts about the safety of water were widespread. This includes the U.S. where 39% of those polled anticipated serious harm from drinking water in the short term.

“Our research highlights that it is imperative both to deliver safe drinking water and to make sure that people have confidence in their water source,” said Joshua Miller, a doctoral student at the UNC Gillings School of Global Public Health and the study’s first author.

The researchers note that it is difficult for consumers to judge the hazards and safety of their water supply because many contaminants are invisible, odorless and tasteless. Without adequate information, many are left to evaluate the safety of their water based on prior experiences, media reports, and personal values and beliefs.

“It’s also possible that people correctly judge the safety of their water,” Young said. “The good people of Flint didn’t trust their water and they were spot on.”

The co-authors suggest actions officials can take to improve public trust around drinking water, including efforts to make testing more readily available, translate test results, replace lead pipes and provide at-home water filters when contaminants are detected, as well as provide improved access to safe drinking water.

“This is the kind of work that can catalyze greater attention and political will to prioritize these services in national development plans and strategies, and get us closer to achieving universal access to safe drinking water,” said Aaron Salzberg, director of the Water Institute at the UNC Gillings School of Global Public Health.

Salzberg previously served as the special coordinator for water resources in the U.S. Department of State, where he was responsible for managing the development and implementation of U.S. foreign policy on drinking water and sanitation, water resources management and transboundary water issues.

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https://www.sciencedaily.com/releases/2024/08/240826182932.htm

Drinking water contaminated with Pfas probably increases risk of infant mortality, study finds

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Study of 11,000 births in New Hampshire shows residents’ reproductive outcomes near contaminated sites

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Drinking water contaminated with Pfas chemicals probably increases the risk of infant mortality and other harm to newborns, a new peer-reviewed study of 11,000 births in New Hampshire finds.

The first-of-its-kind University of Arizona research found drinking well water down gradient from a Pfas-contaminated site was tied to an increase in infant mortality of 191%, pre-term birth of 20%, and low-weight birth of 43%.

It was also tied to an increase in extremely premature birth and extremely low-weight birth by 168% and 180%, respectively.

The findings caught authors by surprise, said Derek Lemoine, a study co-author and economics professor at the University of Arizona who focuses on environmental policymaking and pricing climate risks.

“I don’t know if we expected to find effects this big and this detectable, especially given that there isn’t that much infant mortality, and there aren’t that many extremely low weight or pre-term births,” Lemoine said. “But it was there in the data.”

The study also weighed the cost of societal harms in drinking contaminated water against up-front cleanup costs, and found it to be much cheaper to address Pfas water pollution.

Extrapolating the findings to the entire US population, the authors estimate a nearly $8bn negative annual economic impact just in increased healthcare costs and lost productivity. The cost of complying with current regulations for removing Pfas in drinking water is estimated at about $3.8bn.

“We are trying to put numbers on this and that’s important because when you want to clean up and regulate Pfas, there’s a real cost to it,” Lemoine said.

Pfas are a class of at least 16,000 compounds often used to help products resist water, stains and heat. They are called “forever chemicals” because they do not naturally break down and accumulate in the environment, and they are linked to serious health problems such as cancer, kidney disease, liver problems, immune disorders and birth defects.

Pfas are widely used across the economy, and industrial sites that utilize them in high volume often pollute groundwater. Military bases and airports are among major sources of Pfas pollution because the chemicals are used in firefighting foam. The federal government estimated that about 95 million people across the country drink contaminated water from public or private wells.

Previous research has raised concern about the impact of Pfas exposure on fetuses and newborns.

Among those are toxicological studies in which researchers examine the chemicals’ impact on lab animals, but that leaves some question about whether humans experience the same harms, Lemoine said.

Other studies are correlative and look at the levels of Pfas in umbilical cord blood or in newborns in relation to levels of disease. Lemoine said those findings are not always conclusive, in part because many variables can contribute to reproductive harm.

The new natural study is unique because it gets close to “isolating the effect of the Pfas itself, and not anything around it”, Lemoine said.

Researchers achieved this by identifying 41 New Hampshire sites contaminated with Pfoa and Pfos, two common Pfas compounds, then using topography data to determine groundwater flow direction. The authors then examined reproductive outcomes among residents down gradient from the sites.

Researchers chose New Hampshire because it is the only state where Pfas and reproductive data is available, Lemoine said. Well locations are confidential, so mothers were unaware of whether their water source was down gradient from a Pfas-contaminated site. That created a randomization that allows for causal inference, the authors noted.

The study’s methodology is rigorous and unique, and underscores “that Pfas is no joke, and is toxic at very low concentrations”, said Sydney Evans, a senior science analyst with the Environmental Working Group non-profit. The group studies Pfas exposures and advocates for tighter regulations.

The study is in part effective because mothers did not know whether they were exposed, which created the randomization, Evans said, but she noted that the state has the information. The findings raise questions about whether the state should be doing a similar analysis and alerting mothers who are at risk, Evans said.

Lemoine said the study had some limitations, including that authors don’t know the mothers’ exact exposure levels to Pfas, nor does the research account for other contaminants that may be in the water. But he added that the findings still give a strong picture of the chemicals’ effects.

Granular activated carbon or reverse osmosis systems can be used by water treatment plants and consumers at home to remove many kinds of Pfas, and those systems also remove other contaminants.

The Biden administration last year put in place limits in drinking water for six types of Pfas, and gave water utilities several years to install systems.

The Trump administration is moving to undo the limits for some compounds. That would probably cost the public more in the long run. Utility customers pay the cost of removing Pfas, but the public “also pays the cost of drinking contaminated water, which is bigger”, Lemoine said.

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https://www.theguardian.com/us-news/2025/dec/08/drinking-water-pfas-infant-mortality-study

Tap vs. Bottled Water: Scientists Reveal Which Contained More Chemical Byproducts

Researchers tested spring, groundwater, and purified bottled waters against local tap to see how treatment shapes the byproducts that emerge — and the differences were striking.

By 

Stacey Leasca

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A plastic bottle of water placed on a surface in sunlight
Credit: Ekaterina Goncharova / Getty Images
  • A new study found that bottled water contains lower levels of disinfection byproducts (DBPs) than chloraminated tap water, averaging less than half the amount found in typical U.S. tap samples.
  • Researchers detected DBPs—including trihalomethanes and haloacetic acids—in all 10 bottled water brands tested, though levels remained relatively low.
  • Spring and groundwater brands tended to have fewer DBPs than purified bottled waters, making them the better choice for minimizing chemical byproducts.

The news hasn’t been great for bottled water fans lately. In January, Food & Wine reported on a new study showing that the more bottled water you drink, the more microplastics you consume, and another study showing that bottled water may contain more bacteria than you might expect. And don’t even get us started on what happens when you leave bottled water in a hot car for too long.

Now, a new study published in the journal Water Research is giving bottled water the silver lining it desperately needs. 

In the new March issue, researchers from the University of South Carolina published findings measuring levels of disinfection byproducts (DBPs) in bottled water compared to chloraminated tap water. The study noted that bottled water often begins as municipal tap water, which is sometimes further disinfected. This process, the researchers added, can form DBPs, chemical compounds created when disinfectants react with natural organic matter.

This Is the Bottled Water Brand Americans Reach for Most, According to New Data

The researchers noted that some of these DBPs are already regulated in bottled water by the U.S. Food and Drug Administration (FDA); however, many more fly under the unregulated radar. To find out which ones may be lurking in your water, the researchers purchased 10 popular brands of bottled water from local stores, including lower-cost “grocery” brands, mid-tier “name” brands, and higher-end “designer” brands. Some of the water was labeled as “purified” (often just code for treated tap water), while others were labeled as spring or groundwater. They also collected a sample of local tap water (treated with chloramine) for comparison with the bottled brands.

The researchers then tested for 64 different DBPs, including 50 unregulated DBPs that had not previously been measured in bottled water. They found that every bottled water sample they tested contained some level of disinfection byproducts, but at relatively low levels, ranging from 0.01 to 22.4 micrograms per liter, or up to about 22 millionths of a gram in roughly 34 ounces of water. By comparison, the tap water sample they analyzed contained 47.3 micrograms per liter, and previous studies suggest U.S. tap water averages closer to 52 micrograms per liter, about double the highest bottled water level measured in this study.

Bottled water vs. tap water: How do DBP levels compare?
Water Type DBP Levels in This Study How It’s Treated What to Know 
Purified bottled water 0.01–22.4 µg/L (some samples near the higher end of the bottled range) Often municipal tap water that has been further treated (e.g., reverse osmosis, distillation, or carbon filtration) May still contain DBPs formed during disinfection. Levels varied by lot. 
Spring/groundwater bottled water Generally lower overall DBPs than purified brands Sourced from underground aquifers; may be disinfected but often undergoes less treatment than purified water Showed lower DBP levels in this study, but not DBP-free. 
Chloraminated tap water (sample) 47.3 µg/L Treated with chloramine to kill pathogens Higher DBPs than any bottled sample tested, but within federal regulatory limits. 
Average U.S. tap water (prior research) ~52 µg/L Typically chlorinated or chloraminated Federal EPA limit for total trihalomethanes is 80 µg/L. 

Here’s how disinfection byproduct (DBP) levels in bottled water brands stack up against chloraminated tap water samples and prior U.S. averages.

And a hot tip: If you’re hoping to score the bottled water with the lowest levels of DBPs, go for spring and groundwater, which showed lower overall DBPs than purified brands.

As for which byproducts they identified, the team reported that trihalomethanes and haloacetic acids had the highest concentrations. Both are common DBPs that form when chlorine reacts with organic matter in water. (However, some studies have linked long-term exposure at high levels to an increased risk of certain cancers.) The researchers also found several unregulated DBPs, including dibromoacetonitrile, which is carcinogenic. 

https://www.foodandwine.com/embed?url=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DL7qnquywcZU&id=mntl-sc-block_20-0-iframe&options=e30%3D&docId=11909742

The one thing the team couldn’t do was say with certainty that there is a “safest” brand of water, because DBP levels varied from lot to lot, making brand-level comparisons impossible. As for what’s next, the team hopes their work can inform future studies tracking these DBPs over time to see how they develop as water sits on the shelf.

Tap Water Disinfection May Form Far More Chemical Byproducts Than Regulators Track, Study Finds

Bottom line: Bottled water isn’t DBP-free — but it may contain lower levels than some tap water. If you’re concerned, spring water and proper storage are your best bets. And as always, balance convenience, cost, and environmental impact before stocking up.

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https://www.foodandwine.com/tap-vs-bottled-water-disinfection-byproducts-usc-study-2026-11909742

County-level associations between drinking water PFAS contamination and COVID-19 mortality in the United States

Journal of Exposure Science & Environmental Epidemiology volume 35, pages478–485 (2025)Cite this article

Abstract

Background

Epidemiologic and animal studies both support relationships between exposures to per- and polyfluoroalkyl substances (PFAS) and harmful effects on the immune system. Accordingly, PFAS have been identified as potential environmental risk factors for adverse COVID-19 outcomes.

Objective

Here, we examine associations between PFAS contamination of U.S. community water systems (CWS) and county-level COVID-19 mortality records. Our analyses leverage two datasets: one at the subnational scale (5371 CWS serving 621 counties) and one at the national scale (4798 CWS serving 1677 counties). The subnational monitoring dataset was obtained from statewide drinking monitoring of PFAS (2016–2020) and the national monitoring dataset was obtained from a survey of unregulated contaminants (2013–2015).

Methods

We conducted parallel analyses using multilevel quasi-Poisson regressions to estimate cumulative incidence ratios for the association between county-level measures of PFAS drinking water contamination and COVID-19 mortality prior to vaccination onset (Jan-Dec 2020). In the primary analyses, these regressions were adjusted for several county-level sociodemographic factors, days after the first reported case in the county, and total hospital beds.

Results

In the subnational analysis, detection of at least one PFAS over 5 ng/L was associated with 12% higher [95% CI: 4%, 19%] COVID-19 mortality. In the national analysis, detection of at least one PFAS above the reporting limits (20–90 ng/L) was associated with 13% higher [95% CI: 8%, 19%] COVID-19 mortality.

Impact Statement

  • Our findings provide evidence for an association between area-level drinking water PFAS contamination and higher COVID-19 mortality in the United States. These findings reinforce the importance of ongoing state and federal monitoring efforts supporting the U.S. Environmental Protection Agency’s 2024 drinking water regulations for PFAS. More broadly, this example suggests that drinking water quality could play a role in infectious disease severity. Future research would benefit from study designs that combine area-level exposure measures with individual-level outcome data.

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https://www.nature.com/articles/s41370-024-00723-5?

New solutions to keep drinking water safe as pesticide use skyrockets worldwide

Source:University of South Australia

Summary:Water scientists have proposed a more effective method of removing organic pesticides from drinking water, reducing the risk of contamination and potential health problems.Share:

    

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Water scientists from Australia and China have proposed a more effective method of removing organic pesticides from drinking water, reducing the risk of contamination and potential health problems.

A 62% rise in global pesticide use in the past 20 years has escalated fears that many of these chemicals could end up in our waterways, causing cancer.

Powdered activated carbon (PAC) is currently used to remove organic pesticides from drinking water, but the process is costly, time consuming and not 100% effective.

University of South Australia water researcher Professor Jinming Duan has collaborated with his former PhD student, Dr Wei Li of Xi’an University of Architecture & Technology and Chinese colleagues in a series of experiments to improve the process.

The researchers found that reducing the PAC particles from the existing commercial size of 38 μm (one millionth of a metre) to 6 μm, up to 75% less powder was needed to remove six common pesticides, achieving significant water treatment savings.

At 6 μm, the PAC particles are still large enough to be filtered out after the adsorption process, ensuring they do not end up in the drinking water after toxic pesticides are removed.

Prof Duan says pollutants in our waterways are projected to increase in coming decades as the world’s population and industrial development grows.

“It’s therefore critical that we develop cost-effective treatment processes to ensure our waterways remain safe,” he says.

Their findings have been published in the journal Chemosphere.

“Pesticides cannot be removed using conventional water treatment processes such as flocculation, sedimentation and filtration. Powdered activated carbon does the job, but the existing methods have limitations. Our study has identified how we can make this process more efficient.”

Approximately 3.54 million metric tons of pesticides were applied to agricultural crops worldwide in 2021, according to the Statista Research Department.

Worryingly, despite efforts to increase their efficiency, it is estimated that only 10% of pesticides reach their target pests, with most of the chemicals remaining on plant surfaces or entering the environment, including the soil, waterways and atmosphere.

Toxicological studies have suggested that long-term exposure to low levels of pesticides — primarily through diet or drinking water — could increase the risks of cancer and other diseases.

“This is why it is important to reduce their levels to as low as feasibly possible,” Prof Duan says.

The researchers also hope to explore how super-fine activated carbon could be used to remove toxic polyfluoroalkyl substances (PFAS) and perfluorinated compounds (PFCs) found in many consumer products, which have been linked to adverse health impacts.

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https://www.sciencedaily.com/releases/2024/07/240711111526.htm

Assessing exposure and health consequences of chemicals in drinking water in the 21st Century

Journal of Exposure Science & Environmental Epidemiology volume 34, pages1–2 (2024)Cite this article

Populations worldwide are exposed to a myriad of chemicals via drinking water, yet only a handful of chemicals have been extensively evaluated with regard to human exposures and health impacts [1, 2]. Many chemicals are generally “invisible” in that they do not alter the color or odor of drinking water, and many of the associated effects are not observable for decades, making linkages between exposure and disease difficult. The articles included in the Journal of Exposure Science and Environmental Epidemiology Special Topic “Assessing Exposure and Health Consequences of Chemicals in Drinking Water in the 21st Century” cover a range of topics, including: (i) new exposure and health research for regulated and emerging chemicals, (ii) new methods and tools for assessing exposure to drinking water contaminants, (iii) issues of equity and environmental justice, (iv) drinking water issues within the context of a changing climate. This Special Topic includes articles authored by experts across multiple disciplines including environmental engineering, hydrology, exposure science, epidemiology, toxicology, climate science, and others. Many of these papers emerged from an international symposium organized by ISGlobal and Yale scientists held in Barcelona in September 2022 [3].

Regulated chemicals

Chemicals that have been the focus of environmental health research include disinfection by-products (DBPs), nitrate, and metals. Although many of these chemicals are regulated, there is concern about low-dose exposures at concentrations below standards and guidelines, and risks of health endpoints not yet studied. Kaufman et al. explore new ways to assess DBP exposure, considering concentrations and specific toxicity potential in relation to birth defects risk [4]. Long-term exposure to DBPs and nitrate is addressed by Donat-Vargas et al. in relation to chronic lymphocytic leukaemia in Spain [5]. Friedman et al. examine temporal and spatial variability of manganese concentrations in a case study in the United States (US) [6]. Hefferon et al. evaluated sociodemographic inequalities in fluoride concentrations across the US [7]. Spaur et al. evaluate the contribution of water arsenic to biomarker levels in a prospective study in the US [8].

Chemicals of emerging concern

Many emerging chemicals, such as per- and polyfluoroalkyl substances (PFAS), microplastics, and 1,4-dioxane, have drinking water as the dominant exposure pathway for many populations. Yet, these remain largely unregulated or have standards and guidelines that vary widely across states and countries. Because only small percentages of the universe of contaminants are regulated in drinking water, routine monitoring data for many chemicals of emerging concern is frequently absent or very limited. To advance understanding of drinking water exposures to PFAS, Cserbik et al. [9]. and Kotlarz et al. [10]. evaluate and compare PFAS in drinking water and blood serum samples in two different settings: an urban setting not impacted by PFAS pollution in Spain [9] and among well water users living near a fluorochemical facility in the US [10], respectively.

New methods and tools for exposure assessment

There is a need for improved tools, methods, and data to evaluate drinking water related exposures. These tools and techniques remain somewhat limited and lag behind those of other stressors (e.g., air pollution). Also, despite water contaminants occurring in mixtures, most of the evaluations (and policies and regulations) are conducted chemical by chemical, ignoring potential interactions. Schullehner et al. present case studies of three approaches of exposure assessment of drinking water quality: use of country-wide routine monitoring databases, wide-scope chemical analysis, and effect-based bioassay methods [11]. Luben et al. elaborate and compare different exposure assessment metrics to trihalomethanes in epidemiological analyses of reproductive and developmental outcomes [12]. Escher et al. present in vitro assays to evaluate biological responses of including neurotoxicity, oxidative stress, and cytotoxicity in different types of drinking water samples (tap, bottled, filtered) [13] Isaacs et al. present newly developed automated workflows to screen contaminants of concern based on toxicity and exposure potential [14]. Dorevitch et al. develop a novel method to improve detection of particulate lead spikes [15].

Issues of equity, environmental justice, and vulnerable populations

A substantial portion of the population (e.g., 20% in the United States) have private water supplies (e.g., a household domestic drinking water well), which are not subject to any federal regulatory oversight or monitoring [16]. This presents an equity issue in access to data on drinking water quality, as discussed in Levin et al. [2]. and heterogeneity in state-based policies for drinking water prevention, as discussed by Schmitt et al. [17]. Spaur et al. [8], observed that water from unregulated private wells and regulated municipal water supplies contributes substantially to overall exposures (as measured by urinary arsenic and uranium concentrations) in both rural, American Indian populations and urban, racially/ethnically diverse populations nationwide. Hefferon et al. evaluated environmental justice issues with respect to fluoride and found that 2.9 million US residents are served by public water systems with average fluoride concentrations exceeding the World Health Organization’s guidance limit [7]. Friedman et al. show that manganese in drinking water frequently exceeds current guidelines in the US, and occur at concentrations shown to be associated with adverse health outcomes, especially for vulnerable and susceptible populations like children [6].

Chemical contamination may also pose a serious threat in the developing world. Today, around 2.2 billion people – or 1 in 4 – still lack safely managed drinking water at home [18]. In most of the world, microbial contamination is the biggest challenge. Because it has been understudied, the chemical risks remain obscure [19], and regulators often require local data to take action. Praveena et al. reviews the quality of different drinking water types in Malaysia (tap water, ground water, gravity feed system) and its implications on policy, human health, management, and future research [20].

Water quality in a changing climate

There is an urgent need to anticipate and prepare for current and future challenges in a rapidly changing world. We also need to foresee new challenges to address issues of water scarcity (e.g., increasing desalination, use of treated wastewater in densely populated urban areas to meet water use demands), and aging infrastructure for many middle- and high-income countries constructed in the nineteenth and twentieth centuries. The impacts of climate change on the water cycle are direct and observable, such as more frequent droughts and floods, sea level rise, and ice/snow melt. These events will challenge drinking water quality and availability through direct and indirect mechanisms [21]. There is still very limited knowledge on how climate events will affect the quality of finished drinking water. In our special issue, Oliveras et al. conducts a new analysis on the impacts of drought and heavy rain surrogates on the quality of drinking water in Barcelona, Spain [22].

Conclusion

Chemical contamination of drinking water is widespread. Although our knowledge on chemical risks in drinking water is increasing, there are knowledge gaps that make a slow translation to public health protection. We hope this issue highlights, elevates, and motivates research on chemical exposures via drinking water.

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https://www.nature.com/articles/s41370-024-00639-0

Water chlorination levels in US and EU likely increase cancer risk, study finds

This article is more than 1 year old

Bladder cancer risk increased 33% and colorectal cancer by 15% in using chlorine to disinfect water

Tom Perkins Mon 17 Feb 2025 06.00 ESTShare

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Chlorinating drinking water at levels common in the United States and European Union probably increases the risk of several cancers, a new analysis of recent research from across the globe finds.

The process of disinfecting water with chlorine creates trihalomethane (THM) byproducts, which are found in virtually all public drinking water systems across the US and EU – nearly 300 million people in the US have concerning levels in their water, by one estimate.

While the chlorination process is a “cheap, effective, and readily available” method for killing organisms and infectious disease, it comes with trade-offs, the study’s authors wrote, including a 33% increased risk of bladder cancer and 15% increased risk of colorectal cancer.

“What we see is alarming and we need some more high quality studies,” Emilie Helte, a lead author with Karolinska Institutet in Sweden, said.

An irrigation ditch

The process of disinfecting water is an essential public health measure that dramatically increased life expectancy when the US began chlorinating drinking water in the early 1900s because it significantly reduced microbial infections and waterborne illnesses, like cholera and typhoid fever.

It wasn’t until the 1970s that researchers discovered the process came with consequences. When chlorine is added to water, it reacts with organic compounds, like decaying plant material, to create any number of hundreds of potentially toxic byproducts.

Some of the most common – chloroform, bromoform, bromodichloromethane, and chlorodibromomethane – are known to be genotoxic and carcinogenic to rats.

The US and EU set limits on byproducts at 80 parts per billion (ppb) and 100ppb, respectively, but the new research points to increased cancer risks at levels as low as 40ppb, which is around what they have been found at in New York City. The EPA reports levels are typically in the 40 to 60ppb range and the public health advocacy non-profit Environmental Working Group estimates the safe level at 0.15ppb.

The new meta study is among the most emphatic evidence because it looked at data from about 30 studies and 90,000 participants, and found men were more at risk than women. The authors only looked at bladder and colorectal impacts because there is a dearth of research on other cancers. Researchers are not sure why the chemicals seem to most frequently target the large intestine and bladder, Helte said.

The problem creates a difficult tension for regulators. Surface water typically has higher THM levels than groundwater because it has more organisms and organic matter for the disinfectants to react with. Water utilities could clean some of the organic matter out of the water before disinfecting, and it is also potentially possible to lower the amount of chlorine added, but “it’s really important not to use too little disinfectant”, Helte said.

Alternatives such as treating the water with ultraviolet light or installing new filtration systems are also possible, but are expensive, Helte said.

She stressed that people should continue to drink municipal water. Granulated activated carbon is among the best filtration systems that can be used at home to remove the contaminants.

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https://www.theguardian.com/us-news/2025/feb/17/water-chlorination-cancer-risk-us-eu?

Twenty-year study shows cleaner water slashes cancer and heart disease deaths

Source:Columbia University’s Mailman School of Public Health

Summary:A 20-year project in Bangladesh reveals that lowering arsenic levels in drinking water can slash death rates from major chronic diseases. Participants who switched to safer wells had the same risk levels as people who were never heavily exposed. The researchers tracked individual water exposure with detailed urine testing. Their results show how quickly health improves once contaminated water is replaced.Share:

    

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Safer Wells Save Lives in Bangladesh
Cleaner water dramatically reduces chronic disease deaths, even for those exposed to arsenic for years. Credit: Shutterstock

A large 20-year investigation following nearly 11,000 adults in Bangladesh found that reducing arsenic in drinking water was tied to as much as a 50 percent drop in deaths from heart disease, cancer and several other chronic illnesses. The research offers the strongest long-term evidence so far that lowering arsenic exposure can reduce mortality, even for people who lived with contaminated water for many years. These results appear in JAMA.

Scientists from Columbia University, the Columbia Mailman School of Public Health and New York University led the analysis, which addresses a widespread health concern. Naturally occurring arsenic in groundwater remains a significant challenge across the world. In the United States, more than 100 million people depend on groundwater that can contain arsenic, particularly those using private wells. Arsenic continues to be one of the most common chemical contaminants in drinking water.

“We show what happens when people who are chronically exposed to arsenic are no longer exposed,” said co-lead author Lex van Geen of the Lamont-Doherty Earth Observatory, part of the Columbia Climate School. “You’re not just preventing deaths from future exposure, but also from past exposure.”

Two Decades of Data Strengthen the Evidence

Co-lead author Fen Wu of NYU Grossman School of Medicine said the findings offer the clearest proof yet of the connection between lowering arsenic exposure and reduced mortality risk. Over the course of two decades, the researchers closely tracked participants’ health and repeatedly measured arsenic through urine samples, which strengthened the precision of their analysis.

“Seeing that our work helped sharply reduce deaths from cancer and heart disease, I realized the impact reaches far beyond our study to millions in Bangladesh and beyond now drinking water low in arsenic,” said Joseph Graziano, Professor Emeritus at Columbia Mailman School of Public Health and principal investigator of the NIH-funded program. “A 1998 New York Times story first brought us to Bangladesh. More than two decades later, this finding is deeply rewarding. Public health is often the ultimate delayed gratification.”

Clear Drop in Risk When Arsenic Exposure Falls

People whose urinary arsenic levels fell from high to low had mortality rates that matched those who had consistently low exposure for the entire study. The size of the drop in arsenic was closely tied to how much mortality risk declined. Those who continued drinking high-arsenic water did not show any reduction in chronic disease deaths.

Arsenic naturally accumulates in groundwater and has no taste or smell, meaning people can drink contaminated water for years without knowing it. In Bangladesh, an estimated 50 million people have consumed water exceeding the World Health Organization’s guideline of 10 micrograms per liter. The WHO has described this as the largest mass poisoning in history.

From 2000 to 2022, the Health Effects of Arsenic Longitudinal Study (HEALS) monitored thousands of adults in Araihazar, Bangladesh. The project tested more than 10,000 wells in a region where many families rely on shallow tube wells with arsenic levels ranging from extremely low to dangerously high.

Researchers periodically measured arsenic in participants’ urine, a direct marker of internal exposure, and recorded causes of death. These detailed data allowed the team to compare long-term health outcomes for people who reduced their exposure with those who remained highly exposed.

Community Efforts Created a Natural Comparison Group

Throughout the study period, national and local programs labeled wells as safe or unsafe based on arsenic levels. Many households switched to safer wells or installed new ones, while others continued using contaminated water. This created a natural contrast that helped researchers understand the effects of reducing exposure.

Arsenic exposure decreased substantially in Araihazar during the study. The concentration in commonly used wells fell by about 70 percent as many families sought cleaner water sources. Urine tests confirmed a corresponding decline in internal exposure, averaging a 50 percent reduction that persisted through 2022.

Reduced Exposure Brings Lasting Health Benefits

These trends held true even after researchers accounted for differences in age, smoking and socioeconomic factors. Participants who remained highly exposed, or whose exposure rose over time, continued to face significantly higher risks of death from chronic diseases.

The researchers compared the health benefits of lowering arsenic to quitting smoking. The risks do not disappear immediately but drop gradually as exposure decreases.

In Bangladesh, well testing, labeling unsafe sources, drilling private wells and installing deeper government wells have already improved water safety for many communities.

“Our findings can now help persuade policymakers in Bangladesh and other countries to take emergency action in arsenic ‘hot spots’,” said co-author Kazi Matin Ahmed of the University of Dhaka.

To reach more households, the research team is collaborating with the Bangladeshi government to make well data easier to access. They are piloting NOLKUP (“tubewell” in Bangla), a free mobile app created from more than six million well tests. Users can look up individual wells, review arsenic levels and depths, and locate nearby safer options. The tool also helps officials identify communities that need new or deeper wells.

Clean Water Investments Can Save Lives

The study shows that health risks can fall even for people who were exposed to arsenic for years. This highlights an important opportunity: investing in clean water solutions can save lives within a single generation.

“Sustainable funding to support the collection, storage and maintenance of precious samples and data over more than 20 years have made this critically important work possible,” said Ana Navas-Acien, MD, PhD, Professor and Chair of Environmental Health Sciences at Columbia Mailman School of Public Health. “Science is difficult and there were challenges and setbacks along the way, but we were able to maintain the integrity of the samples and the data even when funding was interrupted, which has allowed us to reveal that preventing arsenic exposure can prevent disease.”

The study team included researchers from Columbia University’s Mailman School of Public Health, the New York University Grossman School of Medicine, Lamont-Doherty Earth Observatory, Boston University School of Public Health, the Department of Geology at the University of Dhaka and the Institute for Population and Precision Health at the University of Chicago.

The HEALS project was launched by Columbia University through the National Institute of Environmental Health Sciences’ Superfund Research Program, with most U.S. collaborators based at Columbia when the study began.

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https://www.sciencedaily.com/releases/2025/11/251127010327.htm?