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1.
Anal Chim Acta ; 1218: 340029, 2022 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-35701038

RESUMO

We have designed and synthesised a novel fluorescent probe with a tetraphenylethylene (TPE) scaffold as an active fluorescent unit and thiosemicarbazide (TSC) group as a recognition unit. The probe, TPE-TSC, exhibited superior selectivity towards hypochlorite (ClO-) with a low limit of detection (2.0 nM). It also demonstrated a turn-off response for a brief period (<30 s) via an oxidation reaction. Furthermore, high-resolution mass spectrometry (HRMS) revealed that TPE-TSC reacted with ClO- by forming a carboxylic acid moiety in nearly 100% aqueous environments. More significantly, the probe detected ClO- in disinfectant, spiked milk samples, and spiked water samples. In all, TPE-TSC proposes an optimistic approach precisely for the determining the quality of milk and water contaminated with ClO- and trace amounts of ClO- in disinfectants.


Assuntos
Desinfetantes , Tiossemicarbazonas , Laticínios/análise , Desinfetantes/análise , Corantes Fluorescentes/química , Ácido Hipocloroso/análise , Espectrometria de Fluorescência , Estilbenos , Tiossemicarbazonas/análise , Água/química
2.
Food Microbiol ; 106: 104033, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35690452

RESUMO

Chlorine and peroxyacetic acid (PAA) are commonly applied in dump tanks and flume systems in commercial fresh apple packing lines; however, little is known about their practical efficacies in dump tank water systems. This study evaluated the efficacies of chlorine and PAA to control Listeria monocytogenes on fresh apples and cross-contamination in simulated dump tank water (SDTW). Efficacies of chlorinated water with initial free chlorine (FC) of 25-100 ppm against L. monocytogenes on apples were significantly impacted by the presence of organic matter, especially for chlorine with 25 ppm initial FC. Chlorine with initial FCs of 50-100 ppm and 2 min contact reduced L. monocytogenes on apples by ∼0.9 log10 CFU/apple in SDTW with 1000 ppm chemical oxygen demand (COD). However, 2-5 min wash of chlorine with 25 ppm initial FC only led to ∼0.3 log10 CFU/apple reduction of L. monocytogenes on apples in SDTW compared to ∼0.9 log10 CFU/apple reduction in clean water. The impacts of organic matter on the antimicrobial efficacy of PAA are concentration dependent. At 20-80 ppm and tested contact times (2-5 min), efficacies of PAA against L. monocytogenes were not influenced by organic matter presented in SDTW; 2-5 min wash with PAA 80 ppm caused 1.7-1.8 log10 CFU/apple log reduction. However, the anti-Listeria efficacy of 10 ppm PAA was significantly lower in SDTW than in clean water. Sanitizers at the tested concentrations reduced L. monocytogenes transferred from contaminated apples to uncontaminated apples and SDTW but did not eliminate it. There were 1.7-0.6 and 1.0-0.9 log10 CFU/apple of L. monocytogenes transferred to uninoculated apples in SDTW treated with 50-100 ppm FC and 60-80 ppm PAA, respectively, for 2 min, while 3.6-3.7 log10 CFU/apple of L. monocytogenes were transferred to uncontaminated apples in SDTW without any sanitizer treatments. Data indicated that sanitizer treatments in SDTW are effective but can be further improved to ensure the microbial safety of apples.


Assuntos
Desinfetantes , Listeria monocytogenes , Malus , Cloro/farmacologia , Contagem de Colônia Microbiana , Desinfetantes/farmacologia , Manipulação de Alimentos , Microbiologia de Alimentos , Ácido Peracético/farmacologia , Água/farmacologia
3.
Molecules ; 27(12)2022 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-35744913

RESUMO

The COVID-19 pandemic has highlighted the relevance of proper disinfection procedures and renewed interest in developing novel disinfectant materials as a preventive strategy to limit SARS-CoV-2 contamination. Given its widely known antibacterial, antifungal, and antiviral properties, Melaleuca alternifolia essential oil, also named Tea tree oil (TTO), is recognized as a potential effective and safe natural disinfectant agent. In particular, the proposed antiviral activity of TTO involves the inhibition of viral entry and fusion, interfering with the structural dynamics of the membrane and with the protein envelope components. In this study, for the first time, we demonstrated the virucidal effects of TTO against the feline coronavirus (FCoVII) and the human coronavirus OC43 (HCoV-OC43), both used as surrogate models for SARS-CoV-2. Then, to atomistically uncover the possible effects exerted by TTO compounds on the outer surface of the SARS-CoV-2 virion, we performed Gaussian accelerated Molecular Dynamics simulations of a SARS-CoV-2 envelope portion, including a complete model of the Spike glycoprotein in the absence or presence of the three main TTO compounds (terpinen-4-ol, γ-terpinene, and 1,8-cineole). The obtained results allowed us to hypothesize the mechanism of action of TTO and its possible use as an anti-coronavirus disinfectant agent.


Assuntos
COVID-19 , Desinfetantes , Melaleuca , Óleo de Melaleuca , Antivirais/farmacologia , COVID-19/tratamento farmacológico , Desinfetantes/farmacologia , Humanos , Melaleuca/química , Pandemias , SARS-CoV-2 , Óleo de Melaleuca/química , Óleo de Melaleuca/farmacologia
4.
J Contemp Dent Pract ; 23(2): 215-220, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-35748452

RESUMO

AIM: The study aimed to evaluate the compressive strength and surface hardness of a type V dental stone after hypochlorite disinfection. MATERIALS AND METHODS: Two types of specimens were made according to the American Dental Association (ADA) specification no. 25 for each wet compressive strength, dry compressive strength, and surface hardness. The specimens were split into three groups with 30 samples each according to the type of disinfection. All specimens were immersed in their respective disinfecting solutions for 30 minutes at room temperature and after removal, they were left to dry for 24 hours at room temperature. Total five cycles of immersion and drying were followed. A compressive strength test was done using a universal testing machine. Wet compressive strength was tested one hour after the last cycle and dry compressive strength was tested 7 days after the last cycle. Surface hardness was measured after 48 hours using Vickers hardness test. The results were statistically analyzed. RESULTS: There was a statistical difference between the calcium hypochlorite and sodium hypochlorite groups for both dry and wet compressive strength. The mean wet compressive strength of calcium hypochlorite was higher when compared to the sodium hypochlorite group and it was statistically significant (p = 0.042). The results were similar and statistically significant (p = 0.003) for dry compressive strength. When the mean surface hardness of the sodium hypochlorite (As) group was compared to calcium hypochlorite the results were highly significant (p = 0.0001) with the mean surface hardness of the calcium hypochlorite group more than the sodium hypochlorite group. CONCLUSION: Calcium hypochlorite used as a disinfectant showed better compressive strength and surface hardness when compared to sodium hypochlorite as a disinfectant. CLINICAL SIGNIFICANCE: Dental casts poured in the contaminated impressions which might not be disinfected at all or properly. They also come in contact with the prosthesis that might be tried inside the patient's mouth and sent to a lab for corrections without disinfecting the cast causing cross-contamination between patients, dentists, and laboratory personnel. However, immersion disinfection with sodium or calcium hypochlorite might affect important properties of the cast. Any negative effect on the mechanical or physical properties of the cast will affect the final outcome of the prosthesis.


Assuntos
Desinfetantes , Ácido Hipocloroso , Sulfato de Cálcio , Força Compressiva , Dureza , Humanos , Teste de Materiais , Hipoclorito de Sódio/farmacologia , Propriedades de Superfície
5.
PLoS One ; 17(6): e0269850, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35759454

RESUMO

The incidence of hospital- and community-acquired infections has been dramatically increased worldwide. Accordingly, hands hygiene and the use of disinfectants have been increased leading to the expansion in hand sanitizers production to meet public demand. This study was conducted to assess the efficiency of common disinfectants in the market of Riyadh, Saudi Arabia in inhibiting the microbial growth during the time of Coronavirus disease 2019 (COVID-19) pandemic. Five bacterial strains of commonly hospital-acquired infections (Pseudomonas aeruginosa, Escherichia coli, Salmonella enteritidis, Staphylococcus aureus, and Enterococcus faecalis) (ATCC reference strains and clinical isolates) were examined for their susceptibility against 18 disinfectants collected from the Saudi market. The tested 18 disinfectants were broadly clustered into different groups based on their active chemical composition as following: 12 products contained alcohol, 2 products had chlorhexidine, 3 products contained mixed concentration of alcohol/chlorhexidine and 1 product had a mixture of chlorhexidine/Hexamidine/Chlorocresol. By measuring the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC), our results revealed that all the 18 disinfectants have reduced the microbial growth of all the tested strains. Generally, the MICs and the MBCs for the clinical strains are higher than those of the reference strains. Taken together, our findings showed that all tested products have high disinfectants' killing rate against microbes of different origins, which suggest the high quality of these disinfectants and the good surveillance practice by the local authorities in Saudi Arabia.


Assuntos
COVID-19 , Desinfetantes , Higienizadores de Mão , COVID-19/prevenção & controle , Clorexidina/farmacologia , Desinfetantes/farmacologia , Escherichia coli , Higienizadores de Mão/farmacologia , Humanos , Esterilização
6.
Sci Total Environ ; 838(Pt 4): 156547, 2022 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-35688238

RESUMO

Dissolved organic matters (DOM) have important effects on the performance of surface water treatment processes and may convert into disinfection by-products (DBPs) during disinfection. In this work, the transformation of DOM and the chlorinated DBPs (Cl-DBPs) formation in two different full-scale surface water treatment processes (process 1: prechlorination-coagulation-precipitation-filtration; process 2: coagulation-precipitation-post-disinfection-filtration) were comparatively investigated at molecular scale. The results showed that coagulation preferentially removed unsaturated (H/C < 1.0 and DBE > 17) and oxidized (O/C > 0.5) compounds containing more carboxyl groups. Therefore, prechlorination produced more Cl-DBPs with H/C < 1.0 and O/C > 0.5 than post-disinfection. However, the algal in the influent produced many reduced molecules (O/C < 0.5) without prechlorination, and these compounds were more reactive with disinfectants. Sand filtration was ineffective in DOM removal, while microorganisms in the filter produced high molecular weight (MW) substances that were involved in the Cl-DBPs formation, causing the generation of higher MW Cl-DBPs under post-disinfection. Furthermore, the CHO molecules with high O atom number and the CHON molecules containing one N atom were the main Cl-DBPs precursors in both surface water treatment processes. In consideration of the putative Cl-DBPs precursors and their reaction pathways, the precursors with higher unsaturation degree and aromaticity were prone to produce Cl-DBPs through addition reactions, while that with higher saturation degree tended to form Cl-DBPs through substitution reactions. These findings are useful to optimize the treatment processes to ensure the safety of water quality.


Assuntos
Desinfetantes , Poluentes Químicos da Água , Purificação da Água , 2,5-Dimetoxi-4-Metilanfetamina , Desinfecção/métodos , Halogenação , Poluentes Químicos da Água/análise , Purificação da Água/métodos
7.
J Hazard Mater ; 436: 129189, 2022 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-35739719

RESUMO

Halobenzoquinones (HBQs) have been reported as an emerging category of disinfection byproducts (DBPs) in drinking water with relatively high toxicity, and the previously reported HBQs include 2,6-dichloro-1,4-benzoquinone, 2,3,6-trichloro-1,4-benzoquinone, 2,6-dichloro-3-methyl-1,4-benzoquinone, 2,6-dibromo-1,4-benzoquinone, 2,6-diiodo-1,4-benzoquinone, 2-chloro-6-iodo-1,4-benzoquinone, and 2-bromo-6-iodo-1,4-benzoquinone. In this study, another HBQ species, 2-bromo-6-chloro-1,4-benzoquinone (2,6-BCBQ), was newly detected and identified in drinking water. The occurrence frequency and levels of 2,6-BCBQ were investigated, and its cytotoxicity was evaluated. Since the formed 2,6-BCBQ was found to be not stable in chlorination, its transformation kinetics and mechanisms in chlorination were further studied. The results reveal that 2,6-BCBQ was generated from Suwannee River humic acid with concentrations in the range of 4.4-47.9 ng/L during chlorination within 120 h, and it was present in all the tap water samples with concentrations ranging from 1.5 to 15.7 ng/L. Among all the tested bromochloro-DBPs, 2,6-BCBQ showed the highest cytotoxicity on the human hepatoma cells. The transformation of 2,6-BCBQ in chlorination followed a pseudo-first-order decay, which was significantly affected by the chlorine dose, pH, and temperature. Seven polar chlorinated and brominated intermediates (including HBQs, halohydroxybenzoquinones, and halohydroxycyclopentenediones) were detected in chlorinated 2,6-BCBQ samples, according to which the transformation pathways of 2,6-BCBQ in chlorination were proposed. Besides, four trihalomethanes and four haloacetic acids were also generated during chlorination of 2,6-BCBQ with molar transformation percentages of 1.6-13.7%.


Assuntos
Desinfetantes , Água Potável , Poluentes Químicos da Água , Purificação da Água , Benzoquinonas/toxicidade , Desinfetantes/análise , Desinfetantes/toxicidade , Desinfecção/métodos , Halogenação , Humanos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
8.
J Hazard Mater ; 436: 129195, 2022 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-35739725

RESUMO

Chlorine dioxide (ClO2) has emerged as a broad-spectrum, safe, and effective disinfectant due to its high oxidation efficiency and reduced formation of organochlorinated by-products during application. This article provides an updated overview of ClO2-based oxidation processes used in water treatment. A systematic review of scientific information and experimental data on ClO2-based water purification procedures is presented. Concerning ClO2-based oxidation derivative problems, the pros and cons of ClO2-based combined processes are assessed and disinfection by-product (DBP) control approaches are proposed. The kinetic and mechanistic data on ClO2 reactivity towards micropollutants are discussed. ClO2 selectively reacts with electron-rich moieties (anilines, phenols, olefins, and amines) and eliminates certain inorganic ions and microorganisms with high efficiency. The formation of chlorite and chlorate during the oxidation process is a crucial concern when utilizing ClO2. Future applications include the combination of ClO2 with ferrous ions, activated carbon, ozone, UV, visible light, or persulfate processes. The combined process can reduce by-product generation while still ensuring ClO2 sterilization and disinfection. Overall, this research could provide useful information and new insights into the application of ClO2-based technologies.


Assuntos
Compostos Clorados , Desinfetantes , Purificação da Água , Cloro , Desinfecção/métodos , Óxidos , Purificação da Água/métodos
9.
J Environ Sci (China) ; 117: 151-160, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725067

RESUMO

Algal blooms and wastewater effluents can introduce algal organic matter (AOM) and effluent organic matter (EfOM) into surface waters, respectively. In this study, the impact of bromide and iodide on the formation of halogenated disinfection byproducts (DBPs) during chlorination and chloramination from various types of dissolved organic matter (DOM, e.g., natural organic matter (NOM), AOM, and EfOM) were investigated based on the data collected from literature. In general, higher formation of trihalomethanes (THMs) and haloacetic acids (HAAs) was observed in NOM than AOM and EfOM, indicating high reactivities of phenolic moieties with both chlorine and monochloramine. The formation of haloacetaldehydes (HALs), haloacetonitriles (HANs) and haloacetamides (HAMs) was much lower than THMs and HAAs. Increasing initial bromide concentrations increased the formation of THMs, HAAs, HANs, and HAMs, but not HALs. Bromine substitution factor (BSF) values of DBPs formed in chlorination decreased as specific ultraviolet absorbance (SUVA) increased. AOM favored the formation of iodinated THMs (I-THMs) during chloramination using preformed chloramines and chlorination-chloramination processes. Increasing prechlorination time can reduce the I-THM concentrations because of the conversion of iodide to iodate, but this increased the formation of chlorinated and brominated DBPs. In an analogous way, iodine substitution factor (ISF) values of I-THMs formed in chloramination decreased as SUVA values of DOM increased. Compared to chlorination, the formation of noniodinated DBPs is low in chloramination.


Assuntos
Desinfetantes , Poluentes Químicos da Água , Purificação da Água , 2,5-Dimetoxi-4-Metilanfetamina , Brometos , Desinfecção , Halogenação , Iodetos , Trialometanos , Poluentes Químicos da Água/análise
10.
J Environ Sci (China) ; 117: 161-172, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725068

RESUMO

A survey was conducted at eight U.S. drinking water plants, that spanned a wide range of water qualities and treatment/disinfection practices. Plants that treated heavily-wastewater-impacted source waters had lower trihalomethane to dihaloacetonitrile ratios due to the presence of more organic nitrogen and HAN precursors. As the bromide to total organic carbon ratio increased, there was more bromine incorporation into DBPs. This has been shown in other studies for THMs and selected emerging DBPs (HANs), whereas this study examined bromine incorporation for a wider group of emerging DBPs (haloacetaldehydes, halonitromethanes). Moreover, bromine incorporation into the emerging DBPs was, in general, similar to that of the THMs. Epidemiology studies that show an association between adverse health effects and brominated THMs may be due to the formation of brominated emerging DBPs of heath concern. Plants with higher free chlorine contact times before ammonia addition to form chloramines had less iodinated DBP formation in chloraminated distribution systems, where there was more oxidation of the iodide to iodate (a sink for the iodide) by the chlorine. This has been shown in many bench-scale studies (primarily for iodinated THMs), but seldom in full-scale studies (where this study also showed the impact on total organic iodine. Collectively, the THMs, haloacetic acids, and emerging DBPs accounted for a significant portion of the TOCl, TOBr, and TOI; however, ∼50% of the TOCl and TOBr is still unknown. The correlation of the sum of detected DBPs with the TOCl and TOBr suggests that they can be used as reliable surrogates.


Assuntos
Desinfetantes , Água Potável , Poluentes Químicos da Água , Purificação da Água , Bromo , Cloro , Desinfetantes/análise , Desinfecção , Halogenação , Iodetos , Trialometanos/análise , Poluentes Químicos da Água/análise
11.
J Environ Sci (China) ; 117: 197-208, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725071

RESUMO

Despite the widespread occurrence of phenols in anthropogenic and natural compounds, their fate in reactions with hypochlorous acid (HOCl), one of the most common water treatment disinfectants, remains incompletely understood. To close this knowledge gap, this study investigated the formation of disinfection by-products (DBPs) in the reaction of free chlorine with seven para-substituted phenols. Based on the chemical structures of the DBPs and the reaction mechanisms leading to their formation, the DBPs were categorized into four groups: chlorophenols, coupling products, substituent reaction products, and ring cleavage products. In contrast to previous studies that investigated the formation of early-stage chlorophenols, the primary focus of this study was on the elucidation of novel ring cleavage products, in particular α, ß-unsaturated C4-dialdehydes, and C4-dicarboxylic acids, which, for the first time, were identified and quantified in this study. The molar yields of 2-butene-1,4-dial (BDA), one of the identified α, ß-unsaturated C4-dialdehydes, varied among the different phenolic compounds, reaching a maximum value of 10.4% for bisphenol S. Molar yields of 2-chloromaleic acid (Cl-MA), one of the identified C4-dicarboxylic acids, reached a maximum value of 30.5% for 4-hydroxy-phenylacetic acid under given conditions. 2,4,6-trichlorophenol (TCP) was shown to be an important intermediate of the parent phenols and the C4-ring cleavage products. Based on the temporal trends of α, ß-unsaturated C4-dialdehydes and C4-dicarboxylic acids, their formation is likely attributable to two separate ring cleavage pathways. Based on the obtained results, an overall transformation pathway for the reaction of para-substituted phenols with free chlorine leading to the formation of novel C4 ring cleavage products was proposed.


Assuntos
Clorofenóis , Desinfetantes , Poluentes Químicos da Água , Purificação da Água , Cloro/química , Clorofenóis/química , Ácidos Dicarboxílicos , Desinfetantes/química , Desinfecção/métodos , Halogenação , Fenóis/química , Poluentes Químicos da Água/química
12.
J Environ Sci (China) ; 117: 209-221, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725072

RESUMO

Water disinfection is an essential process that provides safe water by inactivating pathogens that cause waterborne diseases. However, disinfectants react with organic matter naturally present in water, leading to the formation of disinfection by-products (DBPs). Multi-analyte methods based on mass spectrometry (MS) are preferred to quantify multiple DBP classes at once however, most require extensive sample pre-treatment and significant resources. In this study, two analytical methods were developed for the quantification of 32 regulated and unregulated DBPs. A purge and trap (P&T) coupled with gas chromatography mass spectrometry (GC-MS) method was optimized that automated sample pre-treatment and analyzed volatile and semi-volatile compounds, including trihalomethanes (THMs), iodinated trihalomethanes (I-THMs), haloacetonitriles (HANs), haloketones (HKTs) and halonitromethanes (HNMs). LOQs were between 0.02-0.4 µg/L for most DBPs except for 8 analytes that were in the low µg/L range. A second method with liquid chromatography (LC) tandem mass spectrometry (MS/MS) was developed for the quantification of 10 haloacetic acids (HAAs) with a simple clean-up and direct injection. The LC-MS/MS direct injection method has the lowest detection limits reported (0.2-0.5 µg/L). Both methods have a simple sample pre-treatment, which make it possible for routine analysis. Hyperchlorination and uniform formation conditions (UFC) formation potential tests with chlorine were evaluated with water samples containing high and low TOC. Hyperchlorination formation potential test maximized THMs and HAAs while UFC maximized HANs. Ascorbic acid was found to be an appropriate quencher for both analytical methods. Disinfected drinking water from four water utilities in Alberta, Canada were also evaluated.


Assuntos
Desinfetantes , Água Potável , Poluentes Químicos da Água , Purificação da Água , Cromatografia Líquida , Desinfetantes/análise , Desinfecção/métodos , Água Potável/análise , Halogenação , Espectrometria de Massas em Tandem , Trialometanos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos
13.
J Environ Sci (China) ; 117: 21-27, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725073

RESUMO

Pre-oxidation has been reported to be an effective way to remove algal cells in water, but the released algal organic matter (AOM) could be oxidized and lead to the increment in disinfection by-product (DBP) formation. The relationship between pre-oxidation and AOM-derived DBP formation needs to be approached more precisely. This study compared the impact of four pre-oxidants, ozone (O3), chlorine dioxide (ClO2), potassium permanganate (KMnO4) and sodium hypochlorite (NaClO), on the formation of nitrogenous (N-) and carbonaceous (C-) DBPs in AOM chlorination. The characterization (fluorescent properties, molecular weight distribution and amino acids concentration) on AOM samples showed that the characterization properties variations after pre-oxidation were highly dependent on the oxidizing ability of oxidants. The disinfection experiments showed that O3 increased DBP formation most significantly, which was consistent with the result of characterization properties variations. Then canonical correspondent analysis (CCA) and Pearson's correlation analysis were conducted based on the characterization data and DBP formation. CCA indicated that C-DBPs formation was highly dependent on fluorescent data. The formation of haloacetic acids (HAAs) had a positive correlation with aromatic protein-like component while trichloromethane (TCM) had a positive correlation with fulvic acid-like component. Pearson's correlation analysis showed that low molecular weight fractions were favorable to form N-DBPs. Therefore, characterization data could provide the advantages in the control of DBP formation, which further revealed that KMnO4 and ClO2 were better options for removing algal cells as well as limiting DBP formation.


Assuntos
Desinfetantes , Poluentes Químicos da Água , Purificação da Água , Cloro/química , Corantes/análise , Desinfetantes/análise , Desinfecção , Halogenação , Peso Molecular , Oxidantes , Oxirredução , Água , Poluentes Químicos da Água/análise
14.
J Environ Sci (China) ; 117: 222-231, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725074

RESUMO

Chlorine, chlorine dioxide, and ozone are widely used as disinfectants in drinking water treatments. However, the combined use of different disinfectants can result in the formation of various organic and inorganic disinfection byproducts (DBPs). The toxic interactions, including synergism, addition, and antagonism, among the complex DBPs are still unclear. In this study, we established and verified a real-time cell analysis (RTCA) method for cytotoxicity measurement on Chinese hamster ovary (CHO) cell. Using this convenient and accurate method, we assessed the cytotoxicity of a series of binary combinations consisting of one of the 3 inorganic DBPs (chlorite, chlorate, and bromate) and one of the 32 regulated and emerging organic DBPs. The combination index (CI) of each combination was calculated and evaluated by isobolographic analysis to reflect the toxic interactions. The results confirmed the synergistic effect on cytotoxicity in the binary combinations consisting of chlorite and one of the 5 organic DBPs (2 iodinated DBPs (I-DBPs) and 3 brominated DBPs (Br-DBPs)), chlorate and one of the 4 organic DBPs (3 aromatic DBPs and dibromoacetonitrile), and bromate and one of the 3 organic DBPs (2 I-DBPs and dibromoacetic acid). The possible synergism mechanism of organic DBPs on the inorganic ones may be attributed to the influence of organic DBPs on cell membrane and cell antioxidant system. This study revealed the toxic interactions among organic and inorganic DBPs, and emphasized the latent adverse outcomes in the combined use of different disinfectants.


Assuntos
Desinfetantes , Poluentes Químicos da Água , Animais , Bromatos , Células CHO , Cloratos , Cricetinae , Cricetulus , Desinfetantes/análise , Desinfetantes/toxicidade , Desinfecção , Poluentes Químicos da Água/análise
15.
J Environ Sci (China) ; 117: 232-241, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725075

RESUMO

Disinfectants are added to swimming pools to kill harmful pathogens. Although liquid chlorine (sodium hypochlorite) is the most commonly used disinfectant, alternative disinfection techniques like electrochemically generated mixed oxidants or electrochemically generated chlorine, often referred to as salt water pools, are growing in popularity. However, these disinfectants react with natural organic matter and anthropogenic contaminants introduced to the pool water by swimmers to form disinfection byproducts (DBPs). DBPs have been linked to several adverse health effects, such as bladder cancer, adverse birth outcomes, and asthma. In this study, we quantified 60 DBPs using gas chromatography-mass spectrometry and assessed the calculated cytotoxicity and genotoxicity of an indoor community swimming pool before and after switching to a salt water pool with electrochemically generated chlorine. Interestingly, the total DBPs increased by 15% upon implementation of the salt water pool, but the calculated cytotoxicity and genotoxicity decreased by 45% and 15%, respectively. Predominant DBP classes formed were haloacetic acids, with trichloroacetic acid and dichloroacetic acid contributing 57% of the average total DBPs formed. Haloacetonitriles, haloacetic acids, and haloacetaldehydes were the primary drivers of calculated cytotoxicity, and haloacetic acids were the primary driver of calculated genotoxicity. Diiodoacetic acid, a highly toxic iodinated DBP, is reported for the first time in swimming pool water. Bromide impurities in sodium chloride used to electrochemically generate chlorine led to a 73% increase in brominated DBPs, primarily driven by bromochloroacetic acid. This study presents the most extensive DBP study to-date for salt water pools.


Assuntos
Desinfetantes , Piscinas , Poluentes Químicos da Água , Purificação da Água , Cloro/química , Desinfetantes/análise , Desinfecção/métodos , Halogenação , Água/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
16.
J Environ Sci (China) ; 117: 253-263, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725077

RESUMO

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.


Assuntos
Desinfetantes , Piscinas , Poluentes Químicos da Água , Purificação da Água , Bromo , Cloro/análise , Desinfetantes/análise , Desinfetantes/toxicidade , Desinfecção/métodos , Halogenação , Mutagênicos/análise , Mutagênicos/toxicidade , Água , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
17.
J Environ Sci (China) ; 117: 264-275, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725078

RESUMO

Halogenated disinfection byproducts (DBPs) are an unintended consequence of drinking water disinfection, and can have significant toxicity. XAD resins are commonly used to extract and enrich trace levels of DBPs for comprehensive, nontarget identification of DBPs and also for in vitro toxicity studies. However, XAD resin recoveries for complete classes of halogenated DBPs have not been evaluated, particularly for low, environmentally relevant levels (ng/L to low µg/L). Thus, it is not known whether levels of DBPs or the toxicity of drinking water might be underestimated. In this study, DAX-8/XAD-2 layered resins were evaluated, considering both adsorption and elution from the resins, for extracting 66 DBPs from water. Results demonstrate that among the 7 classes of DBPs investigated, trihalomethanes (THMs), including iodo-THMs, were the most efficiently adsorbed, with recovery of most THMs ranging from 50%-96%, followed by halonitromethanes (40%-90%). The adsorption ability of XAD resins for haloacetonitriles, haloacetamides, and haloacetaldehydes was highly dependent on the individual species. The adsorption capacity of XAD resins for haloacetic acids was lower (5%-48%), even after adjusting to pH 1 before extraction. Recovery efficiency for most DBPs was comparable with their adsorption, as most were eluted effectively from XAD resins by ethyl acetate. DBP polarity and molecular weight were the two most important factors that determine their recovery. Recovery of trichloromethane, iodoacetic acid, chloro- and iodo-acetonitrile, and chloroacetamide were among the lowest, which could lead to underestimation of toxicity, particularly for iodoacetic acid and iodo-acetonitrile, which are highly toxic.


Assuntos
Desinfetantes , Água Potável , Poluentes Químicos da Água , Purificação da Água , Acetonitrilas , Desinfetantes/análise , Desinfetantes/toxicidade , Desinfecção , Halogenação , Iodoacetatos , Trialometanos/análise , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Purificação da Água/métodos
18.
J Environ Sci (China) ; 117: 276-284, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725079

RESUMO

Swimming pools adopt chlorination to ensure microbial safety. Giardia has attracted attention in swimming pool water because of its occurrence, pathogenicity, and chlorine resistance. To control Giardia concentrations in pool water and reduce the microbial risk, higher chlorine doses are required during disinfection. Unfortunately, this process produces carcinogenic disinfection byproducts that increase the risk of chemical exposure. Therefore, quantitatively evaluating the comparative microbial vs. chemical exposure risks that stem from chlorination inactivation of Giardia in swimming pool water is an issue that demands attention. We simulated an indoor swimming pool disinfection scenario that followed common real-world disinfection practices. A quantitative microbial risk assessment coupled with a chemical exposure risk assessment was employed to compare the Giardia microbial exposure risk (MER) and the trihalomethane chemical exposure risk (CER) to humans. The results demonstrated a 22% decrease in MER- and CER-induced health exposure risk, from 8.45E-5 at 8:00 to 6.60E-5 at 19:00. Both the MER and CER decreased gradually, dropping to 3.26E-5 and 3.35E-5 at 19:00, respectively. However, the CER exceeded the MER after 18:30 and became the dominant factor affecting the total exposure risk. Past the 18 hr mark, the contribution of trihalomethane CER far exceeded the risk aversion from microbial inactivation, leading to a net increase in total exposure risk despite the declining MER. Swimmers may consider swimming after 19:00, when the total exposure risk is the lowest. Lowering water temperature and/or pH were identified as the most sensitive factors to minimize the overall health exposure risk.


Assuntos
Desinfetantes , Piscinas , Poluentes Químicos da Água , Cloretos , Cloro/análise , Desinfetantes/análise , Desinfetantes/toxicidade , Desinfecção/métodos , Giardia , Halogênios , Humanos , Trialometanos/análise , Água , Poluentes Químicos da Água/análise
19.
J Environ Sci (China) ; 117: 28-36, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725080

RESUMO

The UV/Cl2 process is commonly used to achieve a multiple-barrier disinfection and maintain residuals. The study chose methylamine as a precursor to study the formation of high-toxic halonitromethanes (HNMs) in the presence of bromide ions (Br-) during UV/Cl2 disinfection. The maximum yield of HNMs increased first and then decreased with increasing concentration of Br-. An excessively high concentration of Br- induced the maximum yield of HNMs in advance. The maximum bromine incorporation factor (BIF) increased, while the maximum bromine utilization factor (BUF) decreased with the increase of Br- concentration. The maximum yield of HNMs decreased as pH value increased from 6.0 to 8.0 due to the deprotonation process. The BUF value remained relatively higher under an acidic condition, while pH value had no evident influence on the BIF value. The maximum yield of HNMs and value of BUF maximized at a Cl2:Br- ratio of 12.5, whereas the BIF value remained relatively higher at low Cl2:Br- ratios (2.5 and 5). The amino group in methylamine was first halogenated, and then released into solution as inorganic nitrogen by the rupture of C-N bond or transformed to nitro group by oxidation and elimination pathways. The maximum yield of HNMs in real waters was higher than that in pure water due to the high content of dissolved organic carbon. Two real waters were sampled to verify the law of HNMs formation. This study helps to understand the HNMs formation (especially brominated species) when the UV/Cl2 process is adopted as a disinfection technique.


Assuntos
Desinfetantes , Poluentes Químicos da Água , Purificação da Água , Brometos/química , Bromo , Cloro/química , Desinfetantes/química , Desinfecção/métodos , Halogenação , Metilaminas , Poluentes Químicos da Água/análise , Purificação da Água/métodos
20.
J Environ Sci (China) ; 117: 285-294, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35725081

RESUMO

In this study, the formation of iodinated trihalomethanes (I-THMs) was systematically evaluated and compared for three treatment processes - (i) chlorination, (ii) monochloramine, and (iii) dichloramination - under different pH conditions. The results demonstrated that I-THM formation decreased in the order of monochloramination > dichloramination > chlorination in acidic and neutral pH. However, the generation of I-THMs increased in the dichloramination < chlorination < monochloramination order in alkaline condition. Specifically, the formation of I-THMs increased as pH increased from 5 to 9 during chlorination and monochloramination processes, while the maximum I-THM formation occurred at pH 7 during dichloramination. The discrepancy could be mainly related to the stability of the three chlor (am) ine disinfectants at different pH conditions. Moreover, in order to gain a thorough insight into the mechanisms of I-THM formation during dichloramination, further investigation was conducted on the influencing factors of DOC concentration and Br-/I- molar ratio. I-THM formation exhibited an increasing and then decreasing trend as the concentration of DOC increased from 1 to 7 mg-C/L, while the yield of I-THMs increased with increasing Br-/I- molar ratio from 5:0 to 5:10. During the three processes mentioned above, similar I-THM formation results were also obtained in real water, which indicates that the excessive generation of I-THMs should be paid special attention during the disinfection of iodide-containing water.


Assuntos
Desinfetantes , Poluentes Químicos da Água , Purificação da Água , Cloro , Desinfecção/métodos , Halogenação , Iodetos , Trialometanos , Água , Poluentes Químicos da Água/análise , Purificação da Água/métodos
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