Disinfection By-products In Water Research Articles

Impacts of iodoacetic acid on reproduction: current evidence, underlying mechanisms, and future research directions.

In light of the undeniable and alarming fact that human fertility is declining, the harmful factors affecting reproductive health are garnering more and more attention. Iodoacetic acid (IAA), an emerging unregulated drinking water disinfection byproduct, derives from chlorine disinfection and is frequently detected in the environment and biological samples. Humans are ubiquitously exposed to IAA daily mainly through drinking water, consuming food and beverages made from disinfected water, contacting swimming pools and bath water, etc. Mounting evidence has indicated that IAA could act as a reproductive toxicant and bring about multifarious adverse reproductive damage. For instance, it can interfere with gonadal development, weaken ovarian function, impair sperm motility, trigger DNA damage to germ cells, perturb steroidogenesis, etc. The underlying mechanisms predominantly include cytotoxic and genotoxic effects on germ cells, disturbance of the hypothalamic-pituitary-gonadal axis, oxidative stress, inhibition of steroidogenic proteins or enzymes, and dysbiosis of gut microbiota. Nevertheless, there are still some knowledge gaps and limitations in studying the potential impact of IAA on reproduction, which urgently need to be addressed in the future. We suppose that necessary population epidemiological studies, more sensitive detection methods for internal exposure, and mechanism-based in-depth exploration will contribute to a more comprehensive understanding of characteristics and biological effects of IAA, thus providing an important scientific basis for revising sanitary standards for drinking water quality.

Control of drinking water disinfection byproducts with a novel bromide-selective anion exchange resin: Design, mechanism, and performance

In regions where drinking water sources containing elevated bromide levels, the formation of brominated disinfection byproducts (Br-DBPs) is enhanced, which may increase risks of cancer and birth defects. Anion exchange resin (AER) adsorption is a promising approach for reducing precursors of Br-DBPs (e.g., bromide and natural organic matter) due to its strong electrostatic force for reversible ion exchange process. However, high bromide water sources typically have high salinities, and the presence of co-existing ions (e.g., sulfate, nitrate, chloride) can significantly diminish the efficiency of conventional AERs, which use polyacrylic or polystyrene skeletons with trimethyl-ammonium functional groups. This study designed a novel AER with the polystyrene skeleton and tripentyl-ammonium functional group for the selective bromide removal, which resisted interferences from co-existing ions based on ion dehydration and ion-pairing electrostatic interactions. Column experiments with continuous high-bromide water flows demonstrated that the novel AER exhibited up to three times the operating capacity of conventional AERs, achieving reductions of 71.2 %, 44.6 %, and 67.7 % in bromide, dissolved organic carbon, and specific UV absorbance, respectively. Competitive experiments showed that the novel AER's strong sulfate interference resistance enhanced its bromide selectivity. The electrostatic interactions between AER fragments and bromide or sulfate particles were quantitatively evaluated using density functional theory calculations. Treatment with the novel AER led to reductions in total organic bromine, aliphatic Br-DBPs, and cyclic Br-DBPs by 76.7 %, 62.5 %, and 90.5 %, respectively. Notably, cytotoxicity assays using Chinese hamster ovary cells indicated a 39.7 % decrease in overall cytotoxicity of chlorinated drinking water following treatment with the novel AER.

Disinfection byproducts in US drinking water and cancer mortality

ABSTRACT Trihalomethanes, the main drinking water disinfection byproducts, may be carcinogenic and are regulated to amaximum total trihalomethanes (TTHM) of 80 µg/l in the US. We aimed to determine whether total and individual trihalomethanes in drinking water across the US are associated with higher cancer mortality in 6,260 adult participants to the National Health and Nutrition Examination Surveys from 1999 to 2008 followed for mortality until 2019 (median: 14.4 years). At baseline, the geometric mean (standard error) of TTHM in drinking water was 9.61 (0.85) µg/l. During follow-up, 873 deaths occurred, including 207 from cancer. In Cox proportional hazards regression adjusted for relevant covariates, drinking water TTHM (HR: 1.45, 95% CI: 1.16–1.82), chloroform (HR: 1.35, 95% CI: 1.12–1.64), and bromodichloromethane (HR: 1.30, 95% CI: 1.05–1.59) were associated with 30% to 45% higher cancer mortality. Therefore, drinking water trihalomethanes, especially chloroform and bromodichloromethane maybe risk factors for cancer mortality.

Nonadditive Cytotoxicity in Select Disinfection Byproducts and Disinfected Secondary Effluents.

Toxicity studies of water disinfection byproducts (DBPs) typically assume additive interactions. Coupling results from both the bottom-up cytotoxicity interaction approach by selecting six common DBPs and the top-down cytotoxicity fractionating the disinfected secondary effluent containing a much broader DBP selection, we demonstrated a novel effect of clear, nonadditive cytotoxicity at low chemical concentrations regardless of the number of DBP types involved. We revealed that the cytotoxicity interactions were influenced by the chemical's type, concentration factor, and mixing ratio. For the bottom-up approach, the average combination indices (CIs) were 1.61 (chloracetamide + chloroacetonitrile, antagonism), 1.03 (bromoacetamide+bromoacetonitrile, near additivity), and 0.69 (iodoacetamide + iodoacetonitrile, synergism) across the DBPs' concentration range of 10-4-10-7 M. These cytotoxicity interactions also varied with the components' mixing ratios. For the top-down approach, we obtained two fractions of DBP mixtures from the disinfected secondary effluent using solvents of different polarities. The effect of the concentration on CI values was significant, with a maximum 43.1% relative deviation in CI from LC5 to LC95. The average CI values across the sample concentration range of 1-50 × (concentration factor) varied from 1.68 (antagonism) to 0.89 (slight synergism) as the ratio of mixture A increased. These results call for further research in prioritizing the forcing DBPs in mixtures.

Constructing ultralow-loading Cu single atoms/Fe2O3 particles on Nb2C MXenes for efficient utilization of atomic H to boost electrochemical debromination

Bromate is a commonly identified carcinogenic and genotoxic disinfection byproduct in water. Electrochemical debromination is an environmentally friendly and effective approach but it often suffers the limited reducing atomic H (H*) ability and high metal catalyst dosage. In this study, a unique composite catalyst comprised of ultra-low loading Cu single atoms (0.016 wt%) and Fe2O3 nanoparticles supported on a Nb2C MXene (denoted as Cu0.2/Fe0.1/Nb2C) was synthesized by one-step high-temperature molten salt method. The Cu0.2/Fe0.1/Nb2C significantly outperformed the Nb2C, Cu0.2/Nb2C and Fe0.1/Nb2C counterparts in the electrochemical debromination with a 94.2 % removal efficiency of bromate. It is revealed that the introducing of Cu single atoms, efficiently promotes the adsorption of H* and inhibition of competitive H2 evolution. The incorporation of Fe2O3 nanoparticles significantly increased the electronic metal-support interaction effect between the metal components and Nb2C, thereby forming a noticeable electronic cloud bridge to facilitate efficient charge transfer. Ultimately, the synergistic interplay between Cu single atoms and Fe2O3 nanoparticles plays a crucial role in achieving the remarkable removal performance of bromate. This work not only presents a significant instance of a synergistic catalyst involving metal single atoms and metal nanoparticles for effective electrochemical debromination but also advances the understanding of the electronic metal-support interaction.

Maternal Exposure to Tap Water Disinfection By-Products and Risk of Selected Congenital Heart Defects.

The use of chlorine to treat drinking water produces disinfection by-products (DBPs), which have been associated with congenital heart defects (CHDs) in some studies. Using National Birth Defects Prevention Study data, we linked geocoded residential addresses to public water supply measurement data for DBPs. Self-reported water consumption and filtration methods were used to estimate maternal ingestion of DBPs. We estimated adjusted odds ratios and 95% confidence intervals using logistic regression controlling for maternal age, education, body mass index (BMI), race/ethnicity, and study site to examine associations between CHDs and both household DBP level and estimated ingestion of DBPs. Household DBP exposure was assessed for 2717 participants (1495 cases and 1222 controls). We observed a broad range of positive, null, and negative estimates across eight specific CHDs and two summary exposures (trihalomethanes and haloacetic acids) plus nine individual DBP species. Examining ingestion exposure among 2488 participants (1347 cases, 1141 controls) produced similarly inconsistent results. Assessing both household DBP level and estimated ingestion of DBPs, we did not find strong evidence of an association between CHDs and DBPs. Despite a large study population, DBP measurements were available for less than half of participant addresses, limiting study power.

The Selectively Nontargeted Analysis of Halogenated Disinfection Byproducts in Tap Water by Micro-LC QTOFMS.

With the rapid development of society, more and more unknown halogenated disinfection byproducts (DBPs) enter into drinking water and pose potential risks to humans. To explore the unknown halogenated DBPs in tap water, a selectively nontargeted analysis (SNTA) method was developed by conducting micro-liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (micro-LC-QTOFMS). In this method, two runs were employed: in the first run, the modes of TOFMS and precursor ion (the fragments were set as Cl35/Cl37, Br79/Br81, and I126.9) were performed, and the molecular ions or precursor ions of the halogenated organics could be obtained; in the second run, the product ion mode was conducted by setting the molecular ion screened above, and the MS/MS spectrums could be acquired to speculate concerning the structure. Two kinds of model DBPs (one kind had an aliphatic structure and the other was an aromatic compound) were used to optimize the parameters of the MS, and their MS characteristics were summarized. With this SNTA method, 15 halogenated DBPs were screened in two tap water samples and their structures were proposed. Of them, six DBPs had not been reported before and were assumed to be new DBPs. Overall, the detected halogenated DBPs were mostly acidic substances.

Control of Aromatic Disinfection Byproducts in Potable Reuse Water by the UV222/H2O2 vs UV254/H2O2 Advanced Oxidation Processes.

Research has demonstrated the difficulty associated with degrading the conventional 1-2 carbon aliphatic halogenated byproducts of disinfectant reactions with organic matter [disinfection byproducts (DBPs)] within advanced oxidation process (AOP) units in potable reuse trains, but the efficacy of AOP units for treating the emerging classes of halogenated aromatic DBPs is unclear. We herein demonstrate more effective removal of 28 halogenated aromatic DBPs in the UV/H2O2 AOP at 222 nm (UV222) than in the conventional UV/H2O2 AOP at 254 nm. Direct photolysis of 28 halogenated aromatic DBPs was greatly enhanced at 222 nm with fluence-based photodecay rate constants of 4.31 × 10-4-1.53 × 10-2 cm2 mJ-1, which was mainly attributed to the higher molar absorption coefficients of halogenated aromatic DBPs at 222 nm than 254 nm. Generally, quantum yields of halogenated aromatic DBPs at both 222 and 254 nm followed the order of halophenols > halohydroxybenzaldehydes > halonitrophenols. All 28 halogenated aromatic DBPs exhibit high reactivity toward HO• with second-order rate constants ranging from 2.18 × 109 to 1.15 × 1010 M-1 s-1 determined by X-ray radiolysis. The UV fluence required to achieve 90% loss of halogenated aromatic DBPs in the UV222/H2O2 AOP was 75-95% lower than that in the UV254/H2O2 AOP, and 90% removal of most tested halogenated aromatic DBPs can be achieved in the UV222/H2O2 AOP within the UV fluence levels commonly applied in potable reuse (700-1000 mJ cm-2).

Biomimetic cytotoxicity control of select nitrogenous disinfection byproducts in water

Nitrogenous disinfection byproducts (N-DBPs) in water are carcinogenic, teratogenic, and mutagenic. In this work, we developed a biomimetic reduction approach based on the cysteine thiol that destructed the highly toxic, select nitrogenous haloacetamides (HAMs) and haloacetonitriles (HANs) while effectively controlling the cytotoxicity of the degradation products to serve as a basis for further technological applications (e.g. immobilized contact bed for terminal users). Mechanisms on toxicity control were elucidated. Results showed the degradation and cytotoxicity control of HAMs as more efficient than that of the HANs. The cytotoxicity of the chlorinated, brominated, and iodinated HAMs and HANs was reduced to 25 %− 0.25 % of the original after biomimetic reduction using a reasonable concentration ratio. Through a combination of thiol-specific reactivity, dehalogenation, and quantitative structure-activity relationship analyses, the major toxicity control mechanisms were found to be the reductive dehalogenation of the N-DBPs. The halogenated functional groups on the N-DBPs had a more pronounced effect than the amide and nitrile groups on the cytotoxicity and detoxification effect. Patterns of toxicity interaction variations with DBPs concentrations were identified to detect possible synergistic cytotoxicity interactions under various combinations of HAMs and HANs in the presence of the cysteine thiol. Results could benefit future N-DBPs control efforts.

P-Coumaric acid pronounced protective effect against potassium bromate-induced hepatic damage in Swiss albino mice.

Potassium bromate (KBrO3) is a common dietary additive, pharmaceutical ingredient, and significant by-product of water disinfection. p-coumaric acid (PCA) is a naturally occurring nutritional polyphenolic molecule with anti-inflammatory and antioxidant activities. The goal of the current investigation was to examine the protective effects of p-coumaric acid against the liver damage caused by KBrO3. The five groups of animals-control, KBrO3 (100 mg/kg bw), treatment with KBrO3 along with Silymarin (100 mg/kg bw), KBrO3, followed by PCA (100 mg/bw, and 200 mg/kg bw) were randomly assigned to the animals. Mice were slaughtered, and blood and liver tissues were taken for assessment of the serum biochemical analysis for markers of liver function (alanine transaminase, aspartate transaminase, alkaline phosphatase, albumin, and protein), lipid markers and antioxidant markers (TBARS), glutathione peroxidase [GSH-Px], glutathione (GSH), and markers of hepatic oxidative stress (CAT), (SOD), as well as histological H&E stain, immunohistochemical stain iNOS, and COX-2 as markers of inflammatory cytokines. PCA protects against acute liver failure by preventing the augmentation of blood biochemical markers and lipid profiles. In mice liver tissues, KBrO3 increases lipid indicators and depletes antioxidants, leading to an increase in JNK, ERK, and p38 phosphorylation. Additionally, PCA inhibited the production of pro-inflammatory cytokines and reduced the histological alterations in KBrO3-induced hepatotoxicity. Notably, PCA effectively mitigated KBrO3-induced hepatic damage by obstructing the TNF-α/NF-kB-mediated inflammatory process signaling system. Additionally, in KBrO3-induced mice, PCA increased the intensities of hepatic glutathione (GSH), SOD, GSH-Px, catalase, and GSH activities. Collectively, we demonstrate the molecular evidence that PCA eliminated cellular inflammatory conditions, mitochondrial oxidative stress, and the TNF-α/NF-κB signaling process, thereby preventing KBrO3-induced hepatocyte damage.

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

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. 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. 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. 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.

Chlorobenzoquinones Aggravate RSL3-Induced Ferroptosis in ROS-Dependent Manner.

Chlorobenzoquinones (CBQs) are a class of emerging water disinfection byproducts that pose significant risks to public health. In this study, we found that three CBQs (tetrachloro-1,4-benzoquinone, 2,5-dichloro-1,4-benzoquinone, and 2-chloro-1,4-benzoquinone) can significantly aggravate cell death caused by Ras-selective lethal small molecule 3 (RSL3). Further study showed that the cell death caused by CBQs, either alone or in combination with RSL3, was related to iron accumulation and GPX4 inactivation, suggesting the occurrence of ferroptosis. Furthermore, reactive oxygen species are found to play a potential key role in mediating the toxicity of CBQs in CBQs and RSL3-induced ferroptosis. These findings will be helpful in understanding the toxic mechanism of CBQs to mammalian cells.

MS and NMR Analysis of Isotopically Labeled Chloramination Disinfection Byproducts: Hyperlinks and Chemical Reactions.

FT-ICR MS and NMR analysis of an isotopically labeled complex mixture of water disinfection byproducts formed by chloramine disinfection of model phenolic acids is described. A new molecular formula assignment procedure using the CoreMS Python library able to assign isotopically enriched formulas is proposed. Statistical analysis of the assigned formulas showed that the number of compounds, the diversity of the mixture, and the chlorine count increase during the chloramination reaction. The complex reaction mixture was investigated as a network of reactions using PageRank and Reverse PageRank algorithms. Independent of the MS signal intensities, the PageRank algorithm calculates the formulas with the highest probability at convergence of the reaction; these were chlorinated and nitrated derivatives of the starting materials. The Reverse PageRank revealed that the most probable chemical transformations in the complex mixture were chlorination and decarboxylation. These agree with the data obtained from INADEQUATE NMR spectra and literature data, indicating that this approach could be applied to gain insight into reactions pathways taking place in complex mixtures without any prior knowledge.

Degradation Strategy and Mechanism of Nitrogenous Disinfection By-products in Three-dimensional Electrochemical System

Nitrosopyrrolidine (NPYR) is a nitrogenous disinfection by-products (N-DBPs) that has attracted much attention due to its high toxicity and resistance to treatment. The removal of NPYR using a three-dimensional aerated electrochemical reactor (3DAER) was investigated. The artificial neural network (ANN) method was employed for the first time to optimize the operating parameters of NPYR degradation with the 3DAER system. Compared to manual parameter optimization, the NPYR degradation parameters generated with the ANN increased the degradation rate by 8.20% to 86.67%. The inhibition rate of the treated water sample used to treat luminescent bacteria was reduced by 49.16%. Mechanistic studies revealed that ·OH and ·O2- were involved in the reaction, and ·OH attacked nucleophilic sites and ·O2- targeted the electrophilic sites of NPYR. Gas chromatographymass spectrometry (GC–MS), combined with Fukui index analyses, was used to elucidate the pathway for NPYR degradation. This confirmed lower biological toxicities for the intermediate products formed during NPYR degradation. In conclusion, the MgFe-LDH/3DAER electrochemical process mitigated the environmental hazards associated with NPYR. This study offers theoretical insights and practical guidance for controlling water disinfection by-products.

Hydrology Predominates Over Harvest History and Landscape Variation to Control Water Quality and Disinfection Byproduct Formation Potentials in Forested Pacific Coast Watersheds.

Despite the global importance of forested watersheds as sources of drinking water, few studies have examined the effects of forestry on drinking water treatability. Relatively little is known about how the interaction between landscape variation and flow impacts source water quality and what this interaction means for drinking water treatability. To address this knowledge gap, we examined variability in sediments, dissolved organic matter, and disinfection byproduct formation potentials (DBP-FPs) across a range of flow conditions in four small watersheds with contrasting forest harvest histories and soil characteristics on Vancouver Island. Storm event-driven change in streamflow was the primary driver of water quality and DBP-FPs at our sites, with greater changes during stormflow (e.g., a 3-fold increase in dissolved organic carbon concentrations) than those across contrasting watersheds. Flow-driven changes in water quality and DBP-FPs were not significantly different across watersheds with different harvest histories; muted responses may be attributed to widespread second growth forests (i.e., recent harvesting effects may be confounded by historical harvest), forestry practices (e.g., slash burning), or soils with low organic carbon storage. This study suggests that variation in hydrology predominates over harvest history and soil characteristics to drive water quality and DBP-FPs on the east coast of Vancouver Island.

Adaptation of water treatment processes for controlling disinfection byproducts in supply waters to compensate the effects of climate change

The water treatment processes (WTPs) need adaptation to climate change. Safe water supply is being challenged by the deteriorating trend of water quality, which can increase disinfection byproducts and impose cancer/non-cancer risks to humans. In this study, implications of climate change and water quality deterioration on the formation of trihalomethanes' (THMs), and risks from 2020 to 2050 were predicted. In 2020, averages of temperature, dissolved organic carbon (DOC) and pH in source waters from Newfoundland (Canada) were 7.92 °C, 6.40 mg/L and 6.53 respectively, which were predicted to be 9.95 °C, 8.56 mg/L and 7.65, respectively in 2050. Three scenarios of free chlorine and bromide ions [(2.0 mg/L, 10 μg/L), (3.5 mg/L, 25 μg/L) and (5.0 mg/L, 50 μg/L)] were simulated. Two models (Model-1 and Model-2) were applied for predicting THMs, risks and allowable DOC for target risks. For Model-1, DOC in 2030, 2040 and 2050 were predicted to be in the ranges of 4.53–4.92, 3.32–3.84 and 2.49–3.06 mg/L respectively to impose similar risks as of 2020. For Model-2, DOC ranges were 5.02–5.95, 3.92–4.99 and 3.60–4.80 mg/L respectively. The lower ranges of DOC in future years were due to increased effects of pH and temperature. To maintain the risks of 2050 to the levels of 2020, WTPs need to reduce DOC by 64.3–70.9 % (Model-1) and 43.8–57.9 % (Model-2). The granular activated carbon filtration is widely used for reducing DOC, which can be further assessed for extensive applications in the WTPs.

Analysis of brominide disinfection by-products (DBPs) in aquaculture water using ultra-high performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-tof/MS).

halogenic disinfectants have been shown to produce toxic and carcinogenic disinfection by-products in the water disinfection process. Dibromohydantoin (DBDMH) is a commonly used water disinfectant in aquaculture. Aquaculture water has more complex matrix, and the analytical method for disinfection by-products (DBPs) have not been reported. Since the content of DBPs is related to the external conditions such as ultraviolet irradiation, temperatures, pH and humic acid. The semi-target screening method for mainly DBPs based on tracing mass spectrometry fragments of bromide and accurate mass of high resolution mass spectrometry was established by ultra performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-tof/MS). Br-DBPs as a important class of DBPs from DBDMH, which quantification analysis methods were developed based on accurate mass of high resolution mass spectrometry. through screening method to identify unknown Br-DBPs and quantitative analysis of the typical 4-bromophenol by-product of accurate mass was established. The conditions of the instrument parameters of mass spectrometry and SPE sample preparation procedure in complex real sample were optimized. The high efficiency method was demonstrated for the determination of Br-DBPs with a good linear correlation (R2 = 0.999) in the range of 0.500-200 μg L-1 and limit of detections (LODs) and limit of quantifications (LOQs) were 0.0250 ng L-1 and 0.0834 ng L-1, respectively. the developed screening and quantification analytical strategy for Br-DBPs is rapid, accurate and sensitivity applicable for environmental in aquaculture water monitoring.

The alternation of halobenzoquinone disinfection byproduct on toxicogenomics of DNA damage and repair in uroepithelial cells

Halobenzoquinones (HBQs) were recently discovered as an emerging class of drinking water disinfection byproducts with carcinogenic concern. However, the molecular mechanism underlying HBQs-induced DNA damage is not clear. In this study, we integrated in vitro genotoxicity, computational toxicology, and the quantitative toxicogenomic analysis of HBQs on DNA damage/repair pathways in human bladder epithelial cells SV-HUC-1. The results showed that HBQs could induce cytotoxicity with the descending order as 2,6-DIBQ > 2,6-DCBQ ≈ 2,6-DBBQ. Also, HBQs can increase DNA damage in SV-HUC-1 cells and thus generate genotoxicity. However, there is no significant difference in genotoxicity among the three HBQs. The results of molecular docking and molecular dynamics simulation further confirmed that HBQs had high binding fractions and stability to DNA. Toxicogenomic analysis indicated that HBQs interfered with DNA repair pathways, mainly affecting base excision repair, nucleotide excision repair and homologous recombination repair. These results have provided new insights into the underlying molecular mechanisms of HBQs-induced DNA damage, and contributed to the understanding of the relationship between exposure to DBPs and risks of developing bladder cancer.

Exposures to drinking water disinfection byproducts and kidney function in Chinese women

BackgroundDisinfection byproducts (DBPs), the ubiquitous contaminants in drinking water, have been shown to impair renal function in experimental studies. However, epidemiological evidence is sparse. ObjectiveTo investigate exposures to DBPs in associations with renal function among women. MethodsA total of 920 women from December 2018 to January 2020 were abstracted from the Tongji Reproductive and Environmental (TREE) Study, an ongoing cohort study in Wuhan, China. Urine samples were gathered at baseline recruitment and analyzed for dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) as biomarkers of DBP exposures. Serum uric acid (UA), creatinine, and estimated glomerular filtration rate (eGFR) were measured as indicators of renal function. Multivariate linear regression and restricted cubic spline (RCS) models were conducted to assess urinary DCAA and TCAA concentrations in associations with renal function indicators. Stratified analyses by age and body mass index (BMI) were also performed. ResultsWe found null evidence of urinary TCAA in associations with renal function indicators. However, elevated urinary DCAA tertiles were related to decreased eGFR (β = −1.78%, 95% CI: 3.21%, −0.36%, comparing the upper vs. lower tertile; P for trend = 0.01). This inverse association still existed when urinary DCAA concentration was treated as a continuous variable, and the dose-response relationship was linear based on the RCS model (P for overall association = 0.002 and P for non-linear associations = 0.44). In the stratified analyses, we found an association of urinary DCAA concentration with decreased UA level among women <30 years but an association with increased UA level among women ≥30 years (P for interaction = 0.04). ConclusionUrinary DCAA but not TCAA was associated with impaired renal function among women undergoing assisted reproductive technology.

Non-regulated haloaromatic water disinfection byproducts act as endocrine and lipid disrupters in human placental cells

The disinfection of drinking water generates hundreds of disinfection byproducts (DBPs), including haloaromatic DBPs. These haloaromatic DBPs are suspected to be more toxic than haloaliphatic ones, and they are currently not regulated. This work investigates their toxicity and ability to interfere with estrogen synthesis in human placental JEG-3 cells, and their genotoxic potential in human alveolar A549 cells. Among the haloaromatic DBPs studied, halobenzoquinones (2,6-dichloro-1,4-benzoquinone (DCBQ) and 2,6-dibromo-1,4-benzoquinone (DBBQ)) showed the highest cytotoxicity (EC50: 18–26 μg/mL). They induced the generation of very high levels of reactive oxygen species (ROS) and up-regulated the expression of genes involved in estrogen synthesis (cyp19a1, hsd17b1). Increased ROS was linked to significant depletion of polyunsaturated lipid species from inner cell membranes. The other DBPs tested showed low or no significant cytotoxicity (EC50 ≥ 100 μg/mL), while 2,4,6-trichloro-phenol (TCP), 2,4,6-tribromo-phenol (TBP) and 3,5-dibromo-4-hydroxybenzaldehyde (DCHB) induced the formation of micronuclei at concentrations much higher than those typically found in water (100 μg/mL). This study reveals the different modes of action of haloaromatic DBPs, and highlights the toxic potential of halobenzoquinones, which had a significant impact on the expression of placenta steroid metabolism related genes and induce oxidative stress, implying potential adverse health effects.