Drinking water safety improvement and future challenge of lakes and reservoirs.

To meet the Sustainable Development Goal (SDG) target 6.1, China has undertaken significant initiatives to address the uneven distribution of water resources and to enhance water quality. Since 2000, China has invested heavily in the water infrastructure of numerous reservoirs, with a total storage capacity increase of 4.704 × 1011 m3 (an increase of 90.8%). These reservoirs have significantly enhanced the available freshwater resources for drinking water. Concurrently, efforts to improve water quality in lakes and reservoirs, facilitated by nationwide water quality monitoring, have been successful. As a result, an increasing lakes and reservoirs are designated as centralized drinking water sources (CDWSs) in China. Among the 3,441 CDWSs across all provinces, 40.8% are sourced from lakes and reservoirs, 32.6% from rivers, and 26.6% from groundwater in 2023. Notably, from 2016 to 2023, the percentage of lakes and reservoirs categorized as CDWSs has increased consistently across all 29 provinces. This progress has enabled 561.4 million urban residents to access improved drinking water sources in 2022, compared to 303.4 million in 2004. Our findings underscore the pivotal role of water infrastructure construction and water quality improvement jointly promoting lakes and reservoirs as vital drinking water sources. Nevertheless, the nationwide occurrence of algal blooms has surged by 113.7% from the 2000s to the 2010s , which is a considerable challenge to drinking water safety. Fortunately, algal blooms have been markedly alleviated in past four years. However, it is still crucial to acknowledge that lakes and reservoirs face the challenges of algal blooms, and associated toxic microcystin and odor compounds.

Evaluation of mortality among Marines, Navy personnel, and civilian workers exposed to contaminated drinking water at USMC base Camp Lejeune: a cohort study.

BACKGROUND: Drinking water at U.S. Marine Corps Base (MCB) Camp Lejeune, North Carolina was contaminated with trichloroethylene and other industrial solvents from 1953 to 1985. METHODS: A cohort mortality study was conducted of Marines/Navy personnel who, between 1975 and 1985, began service and were stationed at Camp Lejeune (N = 159,128) or MCB Camp Pendleton, California (N = 168,406), and civilian workers employed at Camp Lejeune (N = 7,332) or Camp Pendleton (N = 6,677) between October 1972 and December 1985. Camp Pendleton's drinking water was not contaminated with industrial solvents. Mortality follow-up was between 1979 and 2018. Proportional hazards regression was used to calculate adjusted hazard ratios (aHRs) comparing mortality rates between Camp Lejeune and Camp Pendleton cohorts. The ratio of upper and lower 95% confidence interval (CI) limits, or CIR, was used to evaluate the precision of aHRs. The study focused on underlying causes of death with aHRs ≥ 1.20 and CIRs ≤ 3. RESULTS: Deaths among Camp Lejeune and Camp Pendleton Marines/Navy personnel totaled 19,250 and 21,134, respectively. Deaths among Camp Lejeune and Camp Pendleton civilian workers totaled 3,055 and 3,280, respectively. Compared to Camp Pendleton Marines/Navy personnel, Camp Lejeune had aHRs ≥ 1.20 with CIRs ≤ 3 for cancers of the kidney (aHR = 1.21, 95% CI: 0.95, 1.54), esophagus (aHR = 1.24, 95% CI: 1.00, 1.54) and female breast (aHR = 1.20, 95% CI: 0.73, 1.98). Causes of death with aHRs ≥ 1.20 and CIR > 3, included Parkinson disease, myelodysplastic syndrome and cancers of the testes, cervix and ovary. Compared to Camp Pendleton civilian workers, Camp Lejeune had aHRs ≥ 1.20 with CIRs ≤ 3 for chronic kidney disease (aHR = 1.88, 95% CI: 1.13, 3.11) and Parkinson disease (aHR = 1.21, 95% CI: 0.72, 2.04). Female breast cancer had an aHR of 1.19 (95% CI: 0.76, 1.88), and aHRs ≥ 1.20 with CIRs > 3 were observed for kidney and pharyngeal cancers, melanoma, Hodgkin lymphoma, and chronic myeloid leukemia. Quantitative bias analyses indicated that confounding due to smoking and alcohol consumption would not appreciably impact the findings. CONCLUSION: Marines/Navy personnel and civilian workers likely exposed to contaminated drinking water at Camp Lejeune had increased hazard ratios for several causes of death compared to Camp Pendleton.

Efficient adsorption of lead and copper from water by modification of sand filter with a green plant-based adsorbent: Adsorption kinetics and regeneration.

In this study, pomegranate seed waste (PSW) was added into sand filter (SF) to increase removal efficiency of Lead (Pb(II)) and Copper (Cu(II)) from polluted water. The performance of PSW was compared with activated carbon (AC) as a typical adsorbent. Based on the SEM, EDX, FTIR, XRD, BET and proximate analyses, PSW had porous structure with specific surface area of 2.76 m2/g and active compounds which suggested PSW as an appropriate adsorbent for heavy metals (HMs) adsorption. According to the batch experiments, SF without treatment could only remove 46% and 35% of Pb(II) and Cu(II), respectively. These numbers increased to 88% and 75% for Pb(II) and Cu(II) by adding 3 g/kg PSW to the SF, respectively under the optimal conditions of HMs initial concentrations = 100 mg/L, pH = 7 and contact time = 60 min. The adsorption kinetic and isotherm followed the pseudo-first-order and Langmuir models, respectively indicating that mainly physisorption was involved in the HMs adsorption process of PSW. Based on the column experiments (flow rate = 62.5 mL/min), the Pb(II) and Cu(II) removal increased from 14% to 60% and 10%-55%, respectively after 5 pore volumes (40 min) by adding 3 g/kg PSW to the SF. Breakthrough curves matched better with Thomas mode rather than Adam's Bohart proving Langmuir adsorption isotherm. Our finding suggested modification of SF with PSW is a promising approach for efficient removal of HMs from water.

A proposed methodology to evaluate the influence of climate change on drinking water treatments and costs.

Drinking water (DW) production treatments can be affected by climate change, in particular intense rainfall events, having an impact on the availability and quality of the water source. The current study proposes a methodology for the evaluation of the costs of the different treatment steps for surface water (SW) and groundwater (GW), through the analysis and quantification of the main cost items. It provides the details to count for strong variations in the key quality parameters of inlet water following severe rainfalls (namely turbidity, iron, manganese, and E. coli). This methodology is then applied to a large drinking water treatment plant (DWTP) in Italy, which treats both SW, around 70 %, and GW, around 30%. It discusses the overall DW production costs (from 7.60 c€/m3 to 10.43 c€/m3) during the period 2019-2021 and analyzes the contributions of the different treatment steps in water and sludge trains. Then it focuses on the effects on the treatments of significant variations in SW turbidity (up to 1863 NTU) due to intense rainfalls, and on the daily costs of DW with respect to the average (baseline) costs evaluated on the annual basis. It emerges that, when SW has low turbidity levels, the energy-based steps have the biggest contribution on the costs (final pumping 22 % for SW and 10 % for GW, withdrawal 15 % and 14 %, respectively), whereas at very high turbidity levels, sludge greatly increases, and its treatment and disposal costs become significant (up to 14 % and 50 %). Efforts are being made to adopt the best strategies for the management of DWTPs in these adverse conditions, with the aim to guarantee potable water and optimize water production costs. A mitigation measure consists of increasing GW withdrawal up to the authorized flow rate, thus reducing SW withdrawal. In this context, the study is completed by discussing the potential upgrading of the DWTP by only treating GW withdrawn from riverbank filtration. The DW production cost would be 7.76 c€/m3, which is lower than that seen for the same year (2021) with the current plant configuration (8.32 c€/m3).

Nanostructured Magnetic Particles for Removing Cyanotoxins: Assessing Effectiveness and Toxicity In Vitro.

The rise in cyanobacterial blooms due to eutrophication and climate change has increased cyanotoxin presence in water. Most current water treatment plants do not effectively remove these toxins, posing a potential risk to public health. This study introduces a water treatment approach using nanostructured beads containing magnetic nanoparticles (MNPs) for easy removal from liquid suspension, coated with different adsorbent materials to eliminate cyanotoxins. Thirteen particle types were produced using activated carbon, CMK-3 mesoporous carbon, graphene, chitosan, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidised cellulose nanofibers (TOCNF), esterified pectin, and calcined lignin as an adsorbent component. The particles' effectiveness for detoxification of microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-A (ATX-A) was assessed in an aqueous solution. Two particle compositions presented the best adsorption characteristics for the most common cyanotoxins. In the conditions tested, mesoporous carbon nanostructured particles, P1-CMK3, provide good removal of MC-LR and Merck-activated carbon nanostructured particles, P9-MAC, can remove ATX-A and CYN with high and fair efficacy, respectively. Additionally, in vitro toxicity of water treated with each particle type was evaluated in cultured cell lines, revealing no alteration of viability in human renal, neuronal, hepatic, and intestinal cells. Although further research is needed to fully characterise this new water treatment approach, it appears to be a safe, practical, and effective method for eliminating cyanotoxins from water.

Lithium and its effects: does dose matter?

BACKGROUND: Decades of clinical research have demonstrated the efficacy of lithium in treating acute episodes (both manic and depressive), as well as in preventing recurrences of bipolar disorder (BD). Specific to lithium is its antisuicidal effect, which appears to extend beyond its mood-stabilizing properties. Lithium's clinical effectiveness is, to some extent, counterbalanced by its safety and tolerability profile. Indeed, monitoring of lithium levels is required by its narrow therapeutic index. There is consensus that adequate serum levels should be above 0.6 mEq/L to achieve clinical effectiveness. However, few data support the choice of this threshold, and increasing evidence suggests that lithium might have clinical and molecular effects at much lower concentrations. CONTENT: This narrative review is aimed at: (1) reviewing and critically interpreting the clinical evidence supporting the use of the 0.6 mEq/L threshold, (2) reporting a narrative synthesis of the evidence supporting the notion that lithium might be effective in much lower doses. Among these are epidemiological studies of lithium in water, evidence on the antisuicidal, anti-aggressive, and neuroprotective effects, including efficacy in preventing cognitive impairment progression, Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS), of lithium; and (3) revieweing biological data supporting clinically viable uses of lithium at low levels with the delineation of a mechanistic hypothesis surrounding its purported mechanism of action. The study selection was based on the authors' preference, reflecting the varied and extensive expertise on the review subject, further enriched with an extensive pearl-growing strategy for relevant reviews and book sections. CONCLUSIONS: Clinical and molecular effects of lithium are numerous, and its effects also appear to have a certain degree of specificity related to the dose administered. In sum, the clinical effects of lithium are maximal for mood stabilisation at concentrations higher than 0.6 mEq/l. However, lower levels may be sufficient for preventing depressive recurrences in older populations of patients, and microdoses could be effective in decreasing suicide risk, especially in patients with BD. Conversely, lithium's ability to counteract cognitive decline appears to be exerted at subtherapeutic doses, possibly corresponding to its molecular neuroprotective effects. Indeed, lithium may reduce inflammation and induce neuroprotection even at doses several folds lower than those commonly used in clinical settings. Nevertheless, findings surrounding its purported mechanism of action are missing, and more research is needed to investigate the molecular targets of low-dose lithium adequately.

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.

Exploring Rare Earth Element behavior in the Mount Etna volcanic aquifers (Sicily).

This study presents the first data on REY (Rare Earth Elements plus Yttrium) in the aquifer of Mount Etna (Sicily, Italy). Patterns normalized to chondrites indicate strong water-rock interaction, facilitated by a slightly acidic pH resulting from the dissolution of magma-derived CO2. REY patterns provide insights into the processes of both mineral dissolution and the formation of secondary phases. The relative abundance of light to heavy rare earth elements is compatible with the prevailing dissolution of ferromagnesian minerals (e.g., olivine or clinopyroxenes), reinforced by its strong correlation with other proxies of mineral dissolution (e.g., Mg contents). Pronounced negative Ce anomalies and positive Y anomalies demonstrate an oxidizing environment with continuous formation of secondary iron and/or manganese oxides and hydroxides. The Y/Ho fractionation is strongly influenced by metal complexation with bicarbonate complexes, a common process in C-rich waters. In the studied system, the measured REY contents are always below the limits proposed by Sneller et al. (2000, RIVM report, Issue 601,501, p. 66) for surface water and ensure a very low daily intake from drinking water.

Clusters of composition: Elemental content of aquatic organic matter in UK and Faroe peatlands.

Water supply companies with reservoirs in peatland areas need to know how land use and vegetation cover in their supply catchments impact the amount and composition of aquatic organic matter in raw waters. Drinking water treatment processes remove organic matter from potable supplies, but recent increases in concentration and changes in composition have made this more difficult. This study analysed the composition of aquatic organic matter from peatland catchments in the UK and Faroe Islands. Both dissolved organic matter (DOM) and particulate organic matter (POM) compositions varied spatially, but these differences were not consistent as water moved through catchments, from headwaters and peatland pools to lake and reservoir outlets. These data showed that lakes and reservoirs are acting as flocculation hotspots, processing OM, releasing carbon (C), hydrogen (H) and oxygen (O) compounds to the atmosphere, and resulting in OM with higher N content. DOM compositions could be grouped into five clusters, showing that water treatment processes can be maximised to target 'envelopes' or clusters of DOM compositions. Catchment factors such as land use, vegetation cover, percentage peat cover and catchment area are good indicators of OM compositions likely to be present in a reservoir, and can guide water companies to maximise efficiency of their raw water treatment processes.

Maternal periconceptional exposure to drinking water disinfection by-products and neural tube defects in offspring.

BACKGROUND: Associations between maternal periconceptional exposure to disinfection by-products (DBPs) in drinking water and neural tube defects (NTDs) in offspring are inconclusive, limited in part by exposure misclassification. METHODS: Maternal interview reports of drinking water sources and consumption from the National Birth Defects Prevention Study were linked with DBP concentrations in public water system monitoring data for case children with an NTD and control children delivered during 2000-2005. DBPs analyzed were total trihalomethanes, the five most common haloacetic acids combined, and individual species. Associations were estimated for all NTDs combined and selected subtypes (spina bifida, anencephaly) with maternal periconceptional exposure to DBPs in public water systems and with average daily periconceptional ingestion of DBPs accounting for individual-level consumption and filtration information. Mixed effects logistic regression models with maternal race/ethnicity and educational attainment at delivery as fixed effects and study site as a random intercept were applied. RESULTS: Overall, 111 case and 649 control children were eligible for analyses. Adjusted odds ratios for maternal exposure to DBPs in public water systems ranged from 0.8-1.5 for all NTDs combined, 0.6-2.0 for spina bifida, and 0.7-1.9 for anencephaly; respective ranges for average daily maternal ingestion of DBPs were 0.7-1.1, 0.5-1.5, and 0.6-1.8. Several positive estimates (≥1.2) were observed, but all confidence intervals included the null. CONCLUSIONS: Using community- and individual-level data from a large, US, population-based, case-control study, we observed statistically nonsignificant associations between maternal periconceptional exposure to total and individual DBP species in drinking water and NTDs and subtypes.

Reduction of Helicobacter pylori cells in rural water supply using slow sand filtration.

Helicobacter pylori is a microorganism that infects 60% of the population and is considered the main cause of atrophic gastritis, gastric and duodenal ulcers, and gastric cancer. Different emerging pathogens have been found in drinking water and their presence is considered to be an important public health problem. For this reason, it is necessary to carry out the validation of reliable technologies for this type of pathogens and evaluate their performance. This paper reports, for the first time, H. pylori reduction in a drinking water pilot plant of two slow sand filters (SSF). Inlet water was taken from a gravel filtration system of a rural water supply in Colombia and then inoculated with viable cells of H. pylori. By determining the Genomic Units (GU) through quantitative Polymerase Chain Reaction (qPCR), the concentration of GU/sample was measured. In the inlet water amplification for SSF1 and SSF2 were 5.13 × 102 ± 4.48 × 102 and 6.59 × 102 ± 7.32 × 102, respectively, while for the treated water they were 7.0 ± 5.6 and 2.05 × 101 ± 2.9 × 101 GU/sample for SSF1 and SSF2, respectively. The SSF pilot plant reached up to 3 log reduction units of H. pylori; therefore, since there is not an H. pylori contamination indicator and its periodic monitoring is financially complicated, the SSF could guarantee the drinking water quality necessity that exists in rural areas and small municipalities in developing countries, where infection rates and prevalence of this pathogen are high.

Effects of low frequency ultrasound treatment on dissolved organic nitrogen removal by biological activated carbon: Critical insights into molecular characteristics, microbial traits, and metabolism.

Drinking water treatment plants (DWTPs) in China that pioneered the biological activated carbon (BAC) process have reached 10 years of operation. There has been a renewed focus on biofiltration and the performance of old BAC filters for dissolved organic nitrogen (DON) has been poor, requiring replacement and regeneration of the BAC. Therefore, it is necessary to explore a cost-effective way to improve the water quality of the old BAC filters. To address this, low frequency ultrasound is proposed to enhance DON removal efficiency by BAC. In this study, bench and pilot tests were conducted to investigate the effect of low frequency ultrasound on DON removal by 10-year BAC. The results indicated that low frequency ultrasound significantly improved the DON removal rate increased from 15.83 % to 85.87 % and considerably inhibited the nitrogenous disinfection by-products (N-DBPs) formation potential, which was attributed to a decrease in the production of lipid-like, carbohydrate-like, and protein/amino sugar-like DON. The biomass on the BAC was significantly reduced after ultrasound treatment, and it decreased from 349.56∼388.98 nmol P/gBAC to 310.12∼377.63 nmol P/gBAC, enabling the biofilm thickness to decrease and the surface to become sparse and porous, which was conducive to oxygen and nutrients transfer. The Rhizobials associated with microbe-derived DON were stripped away during ultrasound treatment, which reduced microbe-derived DON associated with amino acids. Additionally, ultrasound regulated metabolic pathways, including amino acids, tricarboxylic acid (TCA) cycle, and nucleotide metabolism, to improve the osmotic pressure of the biofilm. In short, low frequency ultrasound treatment can enhance BAC biological properties and effectively remove DON and N-DBPs formation potentials, which provides a viable and promising strategy for improving the safety of drinking water in practice.

Exposure to radon gas in groundwater in southwest Angola (Lubango-Huíla): Implications of geology and climate change.

In southern African countries most of the population uses groundwater collected in dug wells for domestic consumption instead of water from public distribution systems. To investigate the impact of natural and human factors on urban groundwater quality, 276 samples were collected in the Lubango region (Angola) in water distribution systems and dug wells ranging from a few meters to almost one hundred meters in depth. Radon concentrations (RC) were determined by liquid scintillation counting according to ISO 13164-4:2015. Geology is the main source of the variability of RC, with median values higher than 100 Bq/L in granitoid units and lower values in mafic and sedimentary units (ranging from 5 to 38 Bq/L). On average, RC was higher in dug wells compared to public water distribution systems. The annual effective dose due to ingestion of radon in water is, on average, ten times lower in the later compared to dug wells. Therefore, from a public exposure perspective, water distribution systems are preferred as means for water distribution. A severe multi-year meteorological drought over the past decade affecting 76-94 % of the population in southern Angola has been linked with climate change. Consequently, a regional lowering of the water table was observed, as well as a reduction in the productivity of shallower wells, leading to a search for water at greater depths. This work demonstrates an increase in median RC from 66 Bq/L in wells shallower than 30 m to values over 100 Bq/L with increasing depth of water extraction and for the same geological unit. The highest RC observed were also observed at the deepest wells. The dose ingested is proportional to RC, being also higher at deeper water extraction depths. The increase in public radiation exposure from radon ingestion due to water extraction at greater depths is attributed to the underlying issue of climate change. Monitoring water quality in terms of radionuclide concentration is advised to ensure the exposure to ionizing radiation remains at acceptable levels in the future.

The effects of methylparaben exposure on biofilm tolerance to chlorine disinfection.

Parabens are emerging contaminants that have been detected in drinking water. Their presence in DW distribution systems (DWDS) can alter bacterial behaviour, characteristics, and structure, which may compromise DW disinfection. This work provides insights into the impact of methylparaben (MP) on the tolerance to chlorine disinfection and antibiotics from dual-species biofilms formed by Acinetobacter calcoaceticus and Stenotrophomonas maltophilia isolated from DW and grown on high-density polyethylene (HDPE) and polypropylene (PPL). Results showed that dual-species biofilms grown on PPL were more tolerant to chlorine disinfection, expressing a decrease of over 50 % in logarithmic reduction values of culturable cells in relation to non-exposed biofilms. However, bacterial tolerance to antibiotics was not affected by MP presence. Although MP-exposed dual-species biofilms grown on HDPE and PPL were metabolically more active than non-exposed counterparts, HDPE seems to be the material with lower impact on DW risk management and disinfection, if MP is present. Overall, results suggest that MP presence in DW may compromise chlorine disinfection, and consequently affect DW quality and stability, raising potential public health issues.

The resistance change and stress response mechanisms of chlorine-resistant bacteria under microplastic stress in drinking water distribution system.

The presence of both chlorine-resistant bacteria (CRB) and microplastics (MPs) in drinking water distribution systems (DWDS) poses a threat to water quality and human health. However, the risk of CRB bio evolution under the stress of MPs remains unclear. In this study, polypropylene (PP) and polyethylene (PE) were selected to study the adsorption and desorption behavior of sulfamethoxazole (SMX), and it was clear that MPs had the risk of carrying pollutants into DWDS and releasing them. The results of the antibiotic susceptibility test and disinfection experiment confirmed that MPs could enhance the resistance of CRB to antibiotics and disinfectants. Bacteria epigenetic resistance mechanisms were approached from multiple perspectives, including physiological and biochemical characteristics, as well as molecular regulatory networks. When MPs enter DWDS, CRB could attach to the surface of MPs and directly interact with both MPs and the antibiotics they release. This attachment process promoted changes in the composition and content of extracellular polymers (EPS) within cells, enhanced surface hydrophobicity, stimulated oxidative stress function, and notably elevated the relative abundance of certain antibiotic resistance genes (ARGs). This study elucidates the mechanism by which MPs alter the intrinsic properties of CRB, providing valuable insights into the effective avoidance of biological risks to water quality during CRB evolution.

Occurrence, migration and health risks of fluorescent whitening agents and phthalates in bottled water.

The occurrence and health risks of fluorescent whitening agents (FWAs) in bottled water were reported for the first time. FWA184 and FWA393 were the most frequently detected FWAs, with mean concentrations of 3.99-17.00 ng L-1. Phthalates (PAEs) such as dibutyl phthalate (DBP), di-iso-butyl phthalate (DiBP), and diethylhexyl phthalate (DEHP) were prevalent in bottled water, with mean levels of 40.89-716.66 ng L-1, and their concentrations in bottled water were much higher than those of FWAs. FWAs and PAEs in bottles and caps were extracted using organic solvent, and the correlation analysis showed that FWA393 and DEHP most likely originated from bottles, while bottle caps were the main sources of DBP and DiBP. The calculated risk quotients (RQs) of target substances and all age groups were considerably lower than the threshold of 0.1, indicating that consuming bottled water containing these plastic additives was unlikely to pose health risks for people of all ages. However, RQ values for underage people were several times higher than those for adults and hence cannot be neglected; therefore, special attention should be paid to understand the potential risks posed by the exposure to these plastic additives during early life stages, especially the infant stage.

It's getting hot in here: Effects of heat on temperature, disinfection, and opportunistic pathogens in drinking water distribution systems.

As global temperatures rise with climate change, the negative effects of heat on drinking water distribution systems (DWDS) are of increasing concern. High DWDS temperatures are associated with degradation of water quality through physical, chemical and microbial mechanisms. Perhaps the most pressing concern is proliferation of thermotolerant opportunistic pathogens (OPs) like Legionella pneumophila and Naegleria Fowleri. Many OPs can be controlled in DWDS by residual disinfectants such as chlorine or chloramine, but maintaining protective residuals can be challenging at high temperatures. This critical review evaluates the literature on DWDS temperature, residual disinfectant decay, and OP survival and growth with respect to high temperatures. The findings are synthesized to determine the state of knowledge and future research priorities regarding OP proliferation and control at high DWDS temperatures. Temperatures above 40 °C were reported from multiple DWDS, with a maximum of 52 °C. Substantial diurnal temperature swings from ∼30-50 °C occurred in one DWDS. Many OPs can survive or even replicate at these temperatures. However, most studies focused on just a few OP species, and substantial knowledge gaps remain regarding persistence, infectivity, and shifts in microbial community structure at high temperatures relative to lower water temperatures. Chlorine decay rates substantially increase with temperature in some waters but not in others, for reasons that are not well understood. Decay rates within real DWDS are difficult to accurately characterize, presenting practical limitations for application of temperature-dependent decay models at full scale. Chloramine decay is slower than chlorine except in the presence of nitrifiers, which are especially known to grow in DWDS in warmer seasons and climates, though the high temperature range for nitrification is unknown. Lack of knowledge about DWDS nitrifier communities may hinder development of solutions. Fundamental knowledge gaps remain which prevent understanding even the occurrence of high temperatures in DWDS, much less the overall effect on exposure risk. Potential solutions to minimize DWDS temperatures or mitigate the impacts of heat were identified, many which could be aided by proven models for predicting DWDS temperature. Industry leadership and collaboration is needed to generate practical knowledge for protecting DWDS water quality as temperatures rise.

Water residence time is an important predictor of dissolved organic matter composition and drinking water treatability.

Freshwater ecosystems are critical resources for drinking water. In recent decades, dissolved organic matter (DOM) inputs into aquatic systems have increased significantly, particularly in central and northern Europe, due to climatic and anthropogenic drivers. The associated increase in dissolved organic carbon (DOC) concentration can change lake ecosystem services and adversely affect drinking water treatment processes. In this study, we examined spatial and temporal patterns of DOM treatability with granular activated carbon (GAC) and biological reactivity based on 14-day bacterial respiration incubations at 11 sites across Mälaren during six-time points between July 2019 and February 2021. Mälaren is the third largest lake in Sweden and provides drinking water for over 2 million people including the capital city Stockholm. In our spatio-temporal analysis, we assessed the influence of phytoplankton abundance, water chemistry, runoff, and climate on DOM composition, GAC removal efficiency, and biological reactivity. Variations in DOM composition were characterized using optical measurements and Orbitrap mass spectrometry. Multivariate statistical analyses indicated that DOM produced during warmer months was easier to remove by GAC. Removal efficiency of GAC varied from 41 to 87 %, and the best predictor of treatability using mass spectrometry was double bond equivalents (DBE), while the best optical predictors were specific UV absorbance (SUVA), and freshness index. The oxygen consumption rate (k) from the bacterial respiration incubations ranged from 0.04 to 0.71 d-1 and higher in warmer months and at deeper basins and was associated with more aliphatic and fresh DOM. The three deepest lake basins with the longest water residence time (WRT) were temporally the most stable in terms of DOM composition and had the highest DOC removal efficiency and k rates. DOM composition in these three lake basins was optically clearer than in basins located closer to terrestrial inputs and had a signature suggesting it was derived from in-lake processes including phytoplankton production and bacterial processing of terrestrial DOM. This means that with increasing WRT, DOM derived from terrestrial sources shifts to more aquatically produced DOM and becomes easier to remove with GAC. These findings indicate WRT can be highly relevant in shaping DOM composition and thereby likely to affect its ease of treatability for drinking water purposes.

Association between drinking water sources and cognitive functioning in Chinese older adults residing in rural areas.

OBJECTIVES: To explore the association between drinking water sources and cognitive functioning among older adults residing in rural China. METHODS: Data were extracted from the 2008-2018 Chinese Longitudinal Healthy Longevity Survey. Drinking water sources were categorized according to whether purification measures were employed. The Chinese version of the Mini-Mental State Examination was used for cognitive functioning assessment, and the score of <24 was considered as having cognitive dysfunction. Cox regression analyses were conducted to derive hazard ratios (HRs) and 95% confidence intervals (CIs) for the effects of various drinking water sources, changes in such sources, and its interaction with exercise on cognition dysfunction. RESULTS: We included 2304 respondents aged 79.67 ± 10.02 years; of them, 1084 (44.49%) were men. Our adjusted model revealed that respondents consistently drinking tap water were 21% less likely to experience cognitive dysfunction compared with those drinking untreated water (HR = 0.79, 95% CI: 0.70-0.90). Respondents transitioning from natural to tap water showed were 33% less likely to experience cognitive dysfunction (HR = 0.67, 95% CI: 0.58-0.78). Moreover, the HR (95% CI) for the interaction between drinking tap water and exercising was 0.86 (0.75-1.00) when compared with that between drinking untreated water and not exercising. All results adjusted for age, occupation, exercise, and body mass index. CONCLUSIONS: Prolonged tap water consumption and switching from untreated water to tap water were associated with a decreased risk of cognitive dysfunction in older individuals. Additionally, exercising and drinking tap water was synergistically associated with the low incidence of cognitive dysfunction. These findings demonstrate the importance of prioritizing drinking water health in rural areas, indicating that purified tap water can enhance cognitive function among older adults.

Enhancing the DNA yield intended for microbial sequencing from a low-biomass chlorinated drinking water.

DNA extraction yield from drinking water distribution systems and premise plumbing is a key metric for any downstream analysis such as 16S amplicon or metagenomics sequencing. This research aimed to optimize DNA yield from low-biomass (chlorinated) reverse osmosis-produced tap water by evaluating the impact of different factors during the DNA extraction procedure. The factors examined are (1) the impact of membrane materials and their pore sizes; (2) the impact of different cell densities; and (3) an alternative method for enhancing DNA yield via incubation (no nutrient spiking). DNA from a one-liter sampling volume of RO tap water with varying bacterial cell densities was extracted with five different filter membranes (mixed ester cellulose 0.2 µm, polycarbonate 0.2 µm, polyethersulfone 0.2 and 0.1 µm, polyvinylidene fluoride 0.1 µm) for biomass filtration. Our results show that (i) smaller membrane pore size solely did not increase the DNA yield of low-biomass RO tap water; (ii) the DNA yield was proportional to the cell density and substantially dependent on the filter membrane properties (i.e., the membrane materials and their pore sizes); (iii) by using our optimized DNA extraction protocol, we found that polycarbonate filter membrane with 0.2 µm pore size markedly outperformed in terms of quantity (DNA yield) and quality (background level of 16S gene copy number) of recovered microbial DNA; and finally, (iv) for one-liter sampling volume, incubation strategy enhanced the DNA yield and enabled accurate identification of the core members (i.e., Porphyrobacter and Blastomonas as the most abundant indicator taxa) of the bacterial community in low-biomass RO tap water. Importantly, incorporating multiple controls is crucial to distinguish between contaminant/artefactual and true taxa in amplicon sequencing studies of low-biomass RO tap water.