Microplastics that adsorb various toxic contaminants in water may be transported into cells and organs, possibly posing toxicological risks in the aquatic environment. Disinfection byproducts (DBPs), which are ubiquitous in chlorinated drinking water and wastewater, may have some potential to sorb onto microplastics (MPs) through hydrophobic or electrostatic interactions. However, DBP adsorption on microplastics has not yet been closely examined. This work investigated the adsorption behavior of trihalomethanes (THMs)-a regulated and ubiquitous DBP class in chlorinated water-onto virgin and weathered polyvinyl chloride (PVC) microplastics, the most widely used plastic material in drinking water distribution and sewer systems. A comparative analysis of kinetic and isotherm test results indicated that the adsorption mechanisms mainly involved hydrophobic interactions from a combination of weak and strong physisorption behavior and possibly chemisorption. The adsorption coefficients from all the models examined suggested that the adsorption of THMs, and perhaps chemically similar DBPs, onto virgin PVC microplastics can be 10-20 µg g-1. However, the weathered PVC microplastics contained more polar functional groups, which led to a decreased hydrophobicity and reduced THM adsorption capacity by approximately 10%. These findings offer novel insights into the possible adsorption characteristics of disinfection byproducts (DBPs) onto microplastics and will assist in targeting more toxic DBPs for future investigations.

Disinfection during tertiary municipal wastewater treatment is a necessary step to control the spread of pathogens; unfortunately, it also gives rise to numerous disinfection byproducts (DBPs), only a few of which are regulated because of the analytical challenges associated with the vast number of potential DBPs. This study utilized polydimethylsiloxane (PDMS) passive samplers, comprehensive two-dimensional gas chromatography (GC×GC) coupled with time-of-flight mass spectrometry (TOFMS), and non-negative matrix factorization (NMF) spectral deconvolution for suspect screening of DBPs in treated wastewater. PDMS samplers were deployed upstream and downstream of the chlorination unit in a municipal wastewater treatment plant located in Abu Dhabi, and their extracts were analyzed using GC×GC-TOFMS. A workflow incorporating a multi-tiered, eight-filter screening process was developed, which successfully enabled the reliable isolation of 22 candidate DBPs from thousands of peaks. The NMF spectral deconvolution improved the match factor score of unknown mass spectra to the reference mass spectra available in the NIST library by 17% and facilitated the identification of seven additional DBPs. The close match of the first-dimension retention index data and the GC×GC elution patterns of DBPs, both predicted using the Abraham solvation model, with their respective experimental counterparts-with the measured data available in the NIST WebBook and the GC×GC elution patterns being those observed for the candidate peaks-significantly enhanced the accuracy of peak assignment. Isotopic pattern analysis revealed a close correspondence for 11 DBPs with clearly visible isotopologues in reference spectra, thereby further strengthening the confidence in the peak assignment of these DBPs. Brominated analogues were prevalent among the detected DBPs, possibly due to seawater intrusion. The fate, behavior, persistence, and toxicity of tentatively identified DBPs were assessed using EPI Suite™ and the CompTox Chemicals Dashboard. This revealed their significant toxicity to aquatic organisms, including developmental, mutagenic, and endocrine-disrupting effects in certain DBPs. Some DBPs also showed activity in various CompTox bioassays, implicating them in adverse molecular pathways. Additionally, 11 DBPs demonstrated high environmental persistence and resistance to biodegradation. This combined approach offers a powerful tool for future research and environmental monitoring, enabling accurate identification and assessment of DBPs and their potential risks.

Bromhexine and ambroxol are among the mucolytic drugs most widely used to treat acute and chronic respiratory diseases. Entering the municipal wastewater and undergoing transformations during disinfection with active chlorine, these compounds can produce nitrogen- and bromine-containing disinfection by-products (DBPs) that are dangerous for aquatic ecosystems. In the present study, primary and deep degradation products of ambroxol and bromhexine obtained in model aquatic chlorination experiments were studied via the combination of high-performance liquid and gas chromatography with high-resolution mass spectrometry. It was shown that at the initial stages, the reactions of cyclization, hydroxylation, chlorination, electrophilic ipso-substitution of bromine atoms with chlorine, and oxidative N-dealkylation occur. Along with known metabolites, a number of novel primary DBPs were tentatively identified based on their elemental compositions and tandem mass spectra. Deep degradation of bromhexine and ambroxol gives twenty-four identified volatile and semi-volatile compounds of six classes, among which trihalomethanes account for more than 50%. The specific class of bromhexine- and ambroxol-related DBPs are bromine-containing haloanilines. Seven of them, including methoxy derivatives, were first discovered in the present study. One more novel class of DBPs associated with bromhexine and ambroxol is represented by halogenated indazoles formed through dealkylation of the primary transformation products containing pyrazoline or tetrahydropyrimidine cycle in their structure.

In the face of ongoing water pollution challenges, the intricate interplay between dissolved organic matter and disinfectants like chlorine gives rise to potentially harmful disinfection byproducts (DBPs) during water treatment. The exploration of DBP formation originating from amino acids (AA) is a critical focus of global research. Aromatic DBPs, in particular, have garnered considerable attention due to their markedly higher toxicity compared to their aliphatic counterparts. This work seeks to advance the understanding of DBP formation by investigating chlorination disinfection and kinetics using tyrosine (Tyr), phenylalanine (Phe), and tryptophan (Trp) as precursors. Via rigorous experiments, a total of 15 distinct DBPs with accurate molecular structures were successfully identified. The chlorination of all three AAs yielded highly toxic chlorophenylacetonitriles (CPANs), and the disinfectant dosage and pH value of the reaction system potentially influence chlorination kinetics. Notably, Phe exhibited the highest degradation rate compared to Tyr and Trp, at both the CAA:CHOCl ratio of within 1:2 and a wide pH range (6.0 to 9.0). Additionally, a neutral pH environment triggered the maximal reaction rates of the three AAs, while an acidic condition may reduce their reactivity. Overall, this study aims to augment the DBP database and foster a deeper comprehension of the DBP formation and relevant kinetics underlying the chlorination of aromatic AAs.

UNASSIGNED: Trihalomethanes (THMs), a class of DBPs (disinfection byproducts) that includes chloroform, bromodichloromethane (BDCM), chlorodibromomethane (CDBM), and bromoform. To the best of authors\' knowledge, no study has addressed the relationship between the concentration of THMs and lifetime cancer risks (LCR) in drinking water supply system in Addis Ababa, Ethiopia. Therefore, this study aimed to determine the lifetime cancer risks of exposure to THMs in Addis Ababa, Ethiopia.
UNASSIGNED: A total of 120 duplicate water samples were collected from 21 sampling points in Addis Ababa, Ethiopia. The THMs were separated by a DB-5 capillary column and detected by an electron capture detector (ECD). Cancer and non-cancer risk assessments were performed.
UNASSIGNED: The average total THMs (TTHMs)concentration in Addis Ababa, Ethiopia, was 76.3 μg/L. Chloroform was the most dominant THM species identified. The total cancer risk for males was higher than that for females. The average LCR for TTHMs via ingestion in drinking water in this study was unacceptably high risk 93.4 × 10 - 2 . An average LCR through dermal routes was also of unacceptably high risk 4.3 × 10 - 2 . The LCR by chloroform contributes the highest (72%) of the total risk, followed by BDCM (14%), DBCM (10%) and bromoform (4%).
UNASSIGNED: The cancer risk of drinking water due to THMs in Addis Ababa was higher than the level recommended by the USEPA. The total LCR from the targeted THMs was higher via the three exposure routes. Males were at higher THM cancer risk than females. The hazard index (HI) indicated that the dermal route caused higher HI values than the ingestion route. It is essential to apply alternatives to chlorine, i.e., chlorine dioxide (ClO2), ozone and ultraviolet radiation, in Addis Ababa, Ethiopia. The monitoring and regulation of the THMs is required on a regular basis to analyse the trends and guide the water treatment and distribution system.
UNASSIGNED: The datasets generated for this analysis are available from the corresponding author upon reasonable request.

UNASSIGNED: Disinfection byproducts (DBPs) from chlorinated drinking water have been linked to an increased risk of cancer in the bladder, stomach, colon, and rectum. No studies showed the independent trends and prevalence of these cancers in Ethiopia. Therefore, this study aimed to determine the prevalence and trends of disinfection byproducts-related cancers in Addis Ababa, Ethiopia.
UNASSIGNED: Data were collected from the Addis Ababa Cancer Registry. Spatial data sets were produced and classified into households receiving chlorinated surface water and less chlorinated groundwater. The Cochran-Armitage trend test was used to evaluate whether there was a disinfection byproducts-related cancers (DBRCs) trend among communities receiving chlorinated water. Negative binomial regression was used to analyze the incidence rate.
UNASSIGNED: A total of 11, 438 cancer cases were registered between 2012 and 2016, and DBRCs accounted for approximately 17%. The majority of the total cancer cases were female; 7,706 (67%). The prevalence of DBRCs was found to be higher in communities supplied with chlorinated water. From 2012 to 2016, the trend of colon cancer increased (β = 10.3, P value = .034); however, esophageal cancer decreased (β = -6.5, P value = .018). Approximately 56% of colorectal cancer patients and 53% of stomach cancer patients are known to be using chlorinated surface water for drinking regularly. In addition, approximately 57.1% and 54% of kidney and bladder cancer patients, respectively, used chlorinated surface water.
UNASSIGNED: The prevalence of DBRCs in this study was found to be high. The colon cancer trend increased substantially from 2012 to 2016. The prevalence of DBRCs was higher in communities supplied with chlorinated surface water. Similarly, the prevalence of DBRCs was higher among males than females. Further study is required to validate the association between DBRCs and water chlorination.

Although the health benefits of swimming are well-documented, health effects such as asthma and bladder cancer are linked to disinfection by-products (DBPs) in pool water. DBPs are formed from the reaction of disinfectants such as chlorine (Cl) or bromine (Br) with organics in the water. Our previous study (Daiber et al., Environ. Sci. Technol. 50, 6652; 2016) found correlations between the concentrations of classes of DBPs and the mutagenic potencies of waters from chlorinated or brominated swimming pools and spas. We extended this study by identifying significantly different concentrations of 21 individual DBPs in brominated or chlorinated pool and spa waters as well as identifying which DBPs and additional DBP classes were most associated with the mutagenicity of these waters. Using data from our previous study, we found that among 21 DBPs analyzed in 21 pool and spa waters, the concentration of bromoacetic acid was significantly higher in Br-waters versus Cl-waters, whereas the concentration of trichloroacetic acid was significantly higher in Cl-waters. Five Br-DBPs (tribromomethane, dibromochloroacetic acid, dibromoacetonitrile, bromoacetic acid, and tribromoacetic acid) had significantly higher concentrations in Br-spa versus Cl-spa waters. Cl-pools had significantly higher concentrations of Cl-DBPs (trichloroacetaldehyde, trichloromethane, dichloroacetic acid, and chloroacetic acid), whereas Br-pools had significantly higher concentrations of Br-DBPs (tribromomethane, dibromoacetic acid, dibromoacetonitrile, and tribromoacetic acid). The concentrations of the sum of all 4 trihalomethanes, all 11 Br-DBPs, and all 5 nitrogen-containing DBPs were each significantly higher in brominated than in chlorinated pools and spas. The 8 Br-DBPs were the only DBPs whose individual concentrations were significantly correlated with the mutagenic potencies of the pool and spa waters. These results, along with those from our earlier study, highlight the importance of Br-DBPs in the mutagenicity of these recreational waters.

We describe drinking water sources and water quality for a large agricultural cohort. We used questionnaire data from the Agricultural Health Study (N = 89,655), a cohort of licensed pesticide applicators and their spouses in Iowa (IA) and North Carolina (NC), to ascertain drinking water source at enrollment (1993-1997). For users of public water supplies (PWS), we linked participants\' geocoded addresses to contaminant monitoring data [five haloacetic acids (HAA5), total trihalomethanes (TTHM), and nitrate-nitrogen (NO3-N)]. We estimated private well nitrate levels using random forest models accounting for well depth, soil characteristics, nitrogen inputs, and other predictors. We assigned drinking water source for 84% (N = 74,919) of participants. Among these, 69% of IA and 75% of NC participants used private wells; 27% in IA and 21% in NC used PWS. Median PWS nitrate concentrations (NO3-N) were higher in IA [0.9 mg/L, interquartile range (IQR): 0.4-3.1 mg/L] than NC (0.1 mg/L, IQR: 0.1-0.2 mg/L), while median HAA5 and TTHM concentrations were higher in NC (HAA5: 11.9 µg/L, IQR: 5.5-33.4 µg/L; TTHM: 37.7 µg/L, IQR: 10.7-54.7 µg/L) than IA (HAA5: 5.0 µg/L, IQR: 3.7-10.7 µg/L; TTHM: 13.0 µg/L, IQR: 4.2-32.4 µg/L). Private well nitrate concentrations in IA (1.5 mg/L, IQR: 0.8-4.9 mg/L) and NC (1.9 mg/L, IQR: 1.4-2.5 mg/L) were higher than PWS. More private wells in IA (12%) exceeded 10 mg/L NO3-N (regulatory limit for PWS) than NC (<1%). Due to the proximity of their drinking water sources to farms, agricultural communities may be exposed to elevated nitrate levels.

Changes in climate, season, and vegetation can alter organic export from watersheds. While an accepted tradeoff to protect public health, disinfection processes during drinking water treatment can adversely react with organic compounds to form disinfection byproducts (DBPs). By extension, DBP monitoring can yield insights into hydrobiogeochemical dynamics within watersheds and their implications for water resource management. In this study, we analyzed temporal trends from a water treatment facility that sources water from Coal Creek in Crested Butte, Colorado. These trends revealed a long-term increase in haloacetic acid and trihalomethane formation over the period of 2005-2020. Disproportionate export of dissolved organic carbon and formation of DBPs that exceeded maximum contaminant levels were consistently recorded in association with late spring freshet. Synoptic sampling of the creek in 2020 and 2021 identified a biogeochemical hotspot for organic carbon export in the upper domain of the watershed that contained a prominent fulvic acid-like fluorescent signature. DBP formation potential analyses from this domain yielded similar ratios of regulated DBP classes to those formed at the drinking water facility. Spectrometric qualitative analyses of pre and post-reacted waters with hypochlorite indicated lignin-like and condensed hydrocarbon-like molecules were the major reactive chemical classes during chlorine-based disinfection. This study demonstrates how drinking water quality archives combined with synoptic sampling and targeted analyses can be used to identify and understand export control points for dissolved organic matter. This approach could be applied to identify and characterize analogous watersheds where seasonal or climate-associated organic matter export challenge water treatment disinfection and by extension inform watershed management and drinking water treatment.

In this investigation, raw water (RW), settled water (SW), and filtered water (FW) collected from a drinking water treatment plant were fractionated into 24 natural organic matter (NOM) fractions with varying molecular weights and hydrophobicity. The yields of disinfection byproducts (DBPs) obtained during the chlorination of the NOM fractions were explored. Results revealed that the 0-1 kDa, 5-10 kDa, and hydrophobic DBP precursors dominated RW. Hydrophobic fractions cannot be effectively removed, which contributed to the high DBP precursors remaining in the FW. The optional optical parameters, including UVA (UV340, UV360, and UV380), UVB (UV280, UV300, and UV310), and UVC (UV254, UV260, and UV272), were analyzed to determine the DBP yields during chlorination of different NOM fractions. Results revealed that UVC could be applied to indicate the regulated DBP yields of the humified precursors. Contrary to the generally accepted view, for biologically derived precursors, their regulated DBPs and dichloroacetonitrile correlated better with UVA (e.g. UV340). Moreover, PARAFAC analysis was applied to decompose an array of 24 EEM spectra. Good linear correlations were found between the PARAFAC components and most DBP yields. Furthermore, four fluorescence parameters were proposed via a modified fluorescence picking method, which can serve as excellent surrogates of PARAFAC components. These fluorescence parameters were found to be effective in indicating most DBP yields. Finally, the fluorescence intensity at excitation wavelength/emission wavelength = 310/416 nm was found to be a promising built-in parameter for the real-time monitoring of DBP precursors, regardless of the humification degree of the precursors.