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1.
J Environ Sci (China) ; 102: 24-36, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33637249

RESUMO

UV/chlorine process, as an emerging advanced oxidation process (AOP), was effective for removing micro-pollutants via various reactive radicals, but it also led to the changes of natural organic matter (NOM) and formation of disinfection byproducts (DBPs). By using negative ion electrospray ionization coupled with Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS), the transformation of Suwannee River NOM (SRNOM) and the formation of chlorinated DBPs (Cl-DBPs) in the UV/chlorine AOP and subsequent post-chlorination were tracked and compared with dark chlorination. In comparison to dark chlorination, the involvement of ClO•, Cl•, and HO• in the UV/chlorine AOP promoted the transformation of NOM by removing the compounds owning higher aromaticity (AImod) value and DBE (double-bond equivalence)/C ratio and causing the decrease in the proportion of aromatic compounds. Meanwhile, more compounds which contained only C, H, O, N atoms (CHON) were observed after the UV/chlorine AOP compared with dark chlorination via photolysis of organic chloramines or radical reactions. A total of 833 compounds contained C, H, O, Cl atoms (CHOCl) were observed after the UV/chlorine AOP, higher than 789 CHOCl compounds in dark chlorination, and one-chlorine-containing components were the dominant species. The different products from chlorine substitution reactions (SR) and addition reactions (AR) suggested that SR often occurred in the precursors owning higher H/C ratio and AR often occurred in the precursors owning higher aromaticity. Post-chlorination further caused the cleavages of NOM structures into small molecular weight compounds, removed CHON compounds and enhanced the formation of Cl-DBPs. The results provide information about NOM transformation and Cl-DBPs formation at molecular levels in the UV/chlorine AOP.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Cloro/análise , Desinfecção , Halogenação , Espectrometria de Massas , Poluentes Químicos da Água/análise
2.
Sci Total Environ ; 766: 144424, 2021 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-33421790

RESUMO

Residual free chlorine is not monitored continuously at scale in drinking water distribution systems because existing real-time sensor technologies require frequent maintenance, cleaning, and calibration, which makes these products too costly to be used throughout a distribution system. As a result, current measurement approaches require manual sampling, which is not feasible for the consistent monitoring of free chlorine because chlorine concentrations vary significantly throughout pipeline distribution and over time and space. This research presents an alternative and cost-effective method of predicting free chlorine levels in drinking water using graphite electrodes coated with naturally grown microbial biofilms. This Microbial Potentiometric Sensor (MPS) array was installed in a Continuously Mixed Batch Reactor (CMBR), and drinking water containing variable free chlorine concentrations. The chlorine concentrations were introduced in a controlled manner, and the MPS signals were monitored over time. MPS signals were measured from the change in Open Circuit Potential (OCP) across the MPS array in real-time. An empirically derived relationship between the normalized change in OCP and free chlorine was established by fitting individual and average MPS data to a decaying exponential growth function in order to predict free chlorine levels. The results show that free chlorine can be predicted with reasonable accuracy, with model validation showing an average absolute error of ±0.09 ppm below 1.1 ppm and ±0.30 ppm between 1.1 and 2.7 ppm. However, the accuracy of predictions was reduced at higher free chlorine levels. The researchers conclude that MPS systems may benefit drinking water distribution systems by measuring free chlorine. These advantages of the MPS are especially pronounced in the developing world because this system is inexpensive and does not require routine maintenance or cleaning. The system relies on a naturally forming and regenerating biofilm and an inexpensive potentiometric meter to produce stable measurements.


Assuntos
Água Potável , Purificação da Água , Biofilmes , Cloro/análise , Microbiologia da Água , Abastecimento de Água
3.
Environ Sci Pollut Res Int ; 28(7): 7691-7709, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33400105

RESUMO

Chlorine (Cl) in the terrestrial environment is of interest from multiple perspectives, including the use of chloride as a tracer for water flow and contaminant transport, organochlorine pollutants, Cl cycling, radioactive waste (radioecology; 36Cl is of large concern) and plant science (Cl as essential element for living plants). During the past decades, there has been a rapid development towards improved understanding of the terrestrial Cl cycle. There is a ubiquitous and extensive natural chlorination of organic matter in terrestrial ecosystems where naturally formed chlorinated organic compounds (Clorg) in soil frequently exceed the abundance of chloride. Chloride dominates import and export from terrestrial ecosystems while soil Clorg and biomass Cl can dominate the standing stock Cl. This has important implications for Cl transport, as chloride will enter the Cl pools resulting in prolonged residence times. Clearly, these pools must be considered separately in future monitoring programs addressing Cl cycling. Moreover, there are indications that (1) large amounts of Cl can accumulate in biomass, in some cases representing the main Cl pool; (2) emissions of volatile organic chlorines could be a significant export pathway of Cl and (3) that there is a production of Clorg in tissues of, e.g. plants and animals and that Cl can accumulate as, e.g. chlorinated fatty acids in organisms. Yet, data focusing on ecosystem perspectives and combined spatiotemporal variability regarding various Cl pools are still scarce, and the processes and ecological roles of the extensive biological Cl cycling are still poorly understood.


Assuntos
Cloro , Ecossistema , Cloretos/análise , Cloro/análise , Halogenação , Solo
4.
Food Chem ; 335: 127651, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-32739817

RESUMO

We establish the total amino acids (AA) concentration in wash water as an alternative indicator of free chlorine (FC) levels, and develop a model to predict FC concentration based on modeling the reaction kinetics of chlorine and amino acids. Using single wash of iceberg lettuce, green cabbage, and carrots, we report the first in situ apparent reaction rate ß between FC and amino acids in the range of 15.3 - 16.6 M-1 s-1 and an amplification factor γ in the range of 11.52-11.94 for these produce. We also report strong linear correlations between AA levels and produce-to-water ratio (R2 = 0.87), and between chemical oxygen demand (COD) and AA concentrations (R2 = 0.87). The values of the parameters γ and ß of the model were validated in continuous wash experiments of chopped iceberg lettuce, and predicted the FC (R2 = 0.96) and AA (R2 = 0.92) levels very well.


Assuntos
Aminoácidos/análise , Brassica/química , Cloro/análise , Daucus carota/química , Desinfetantes/análise , Manipulação de Alimentos/instrumentação , Alface/química , Contaminação de Alimentos/análise , Manipulação de Alimentos/métodos , Microbiologia de Alimentos
5.
Chemosphere ; 263: 127954, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32854008

RESUMO

Chlorine disinfection is required to inactivate pathogens in drinking water, but it inevitably generates potentially toxic halogenated disinfection byproducts (halo-DBPs). A previous study has reported that the addition of ascorbate to tap water before boiling could significantly decrease the concentration of overall halo-DBPs in the boiled water. Since the fruit lemon is rich in vitamin C (i.e., ascorbic acid), adding it to tap water followed by heating and boiling in an effort to decrease levels of halo-DBPs was investigated in this study. We examined three approaches that produce lemon water: (i) adding lemon to tap water at room temperature, termed "Lemon"; (ii) adding lemon to boiled tap water (at 100 °C) and then cooling to room temperature, termed "Boiling + Lemon"; and (iii) adding lemon to tap water then boiling and cooling to room temperature, termed "Lemon + Boiling". The concentrations of total and individual halo-DBPs in the resultant water samples were quantified with high-performance liquid chromatography-tandem mass spectrometry and the cytotoxicity of DBP mixtures extracted from the water samples was evaluated using human epithelial colorectal adenocarcinoma Caco-2 cells and hepatoma HepG2 cells. Our results show that the "Lemon + Boiling" approach substantially decreased the concentrations of halo-DBPs and the cytotoxicity of tap water. This strategy could be applied to control halo-DBPs, as well as to lower the adverse health effects of halo-DBPs on humans through tap water ingestion.


Assuntos
Ácido Ascórbico/química , Desinfecção/métodos , Ácido Ascórbico/análise , Células CACO-2 , Cloro/análise , Desinfetantes/química , Água Potável/química , Halogenação , Humanos , Poluentes Químicos da Água/análise , Purificação da Água/métodos
6.
An Real Acad Farm ; 86(4): 231-236, oct.-dic. 2020. tab, ilus, graf
Artigo em Inglês | IBECS | ID: ibc-197109

RESUMO

INTRODUCTION AND OBJECTIVES: In the context of COVID-19, the World Health Organization has recommended the use of extemporaneously prepared bleach solutions of 1 g/L, as a conservative concentration able to inactivate SARS-CoV-2 and the vast majority of other pathogens that may be present in the healthcare setting. Consequently, there is a renewed interest in conducting stability studies of these solutions. The goal of this work was to verify the available chlorine concentration in several bleach solutions trademarks and to propose a beyond use date for 1 g/L bleach solutions, obtained after dilution with drinking water from different sources. METHODS: Bleach trademarks, with nominal concentrations between 25-60 g/L, were subjected to iodometric titration to determine the available chlorine concentration. One trademark was used to prepare 1 g/L dilutions using water from different purification plants in Córdoba, Argentina. The samples were stored at room-temperature, both exposed or protected from light. The available chlorine concentration was determined by titration at preestablished time intervals. The beyond use date was reached when the available chlorine concentration dropped below 90 % of its initial. RESULTS: The concentration of active chlorine in the different trademark bleaches was within the values established by current regulations. Diluted solutions protected from light showed a decrease of less than 10 % in active chlorine concentration during the first 10 days of assay. However, one sample exceeded the acceptance limit after 14 days. In contrast, in the samples exposed to light, the concentration of active chlorine dropped to 96.4 % at 24 hours and 79.3 % after 48 hours. No differences related to drinking water sources were observed. CONCLUSIONS: Compliance of the nominal available chlorine concentration in trademark bleach solutions was confirmed. Regardless the water source used for dilution, 1 g/L bleach solutions were stable for 10 days when stored at room temperature and protected from light. Instead, solutions exposed to light maintain their available chlorine concentration for only 24 hours


INTRODUCCIÓN Y OBJETIVOS: En el contexto de COVID-19, la Organización Mundial de la Salud recomienda el uso de soluciones de hipoclorito de sodio 1 g/L, como una concentración capaz de inactivar el SARS-CoV-2 y la gran mayoría de patógenos presentes en el entorno sanitario. En consecuencia, hay un renovado interés en realizar estudios de estabilidad de estas disoluciones. El objetivo de este trabajo es verificar la concentración de cloro activo en varias marcas comerciales de hipoclorito de sodio y proponer una fecha límite de uso para soluciones de 1 g/L, obtenidas por dilución con agua potable proveniente de diferentes fuentes. MÉTODOS: La concentración de cloro activo de preparaciones comerciales con concentración nominal entre 25-60 g/L fue valorada por titulación iodométrica. A partir de una de las marcas comerciales se prepararon diluciones de 1 g/L usando agua proveniente de diferentes plantas potabilizadoras en Córdoba, Argentina. Las disoluciones se almacenaron a temperatura ambiente, tanto expuestas como protegidas de la luz y fueron posteriormente tituladas a intervalos de tiempo preestablecidos. La fecha límite de uso se alcanzó cuando la concentración de cloro activo cayó por debajo del 90 % de la inicial. RESULTADOS: La concentración de cloro activo en las soluciones comerciales estuvo dentro de los valores establecidos por la normativa vigente. Las diluciones protegidas de la luz mostraron una disminución menor al 10 % en la concentración de cloro activo durante los primeros 10 días de ensayo. Sin embargo, una muestra superó el límite de aceptación luego de 14 días. En contraste, en las muestras expuestas a la luz, la concentración de cloro activo cayó a 96.4 % a las 24 horas y 79.3 % después de 48 horas. No se observaron diferencias relacionadas con las fuentes de agua potable. CONCLUSIONES: se confirmó la concentración nominal de cloro activo en todas las marcas comerciales evaluadas. Independientemente de la fuente de agua potable utilizada para la dilución, las soluciones de 1 g/L fueron estables durante 10 días cuando se almacenaron a temperatura ambiente y protegidas de la luz. En contraste, las soluciones expuestas a la luz mantienen la concentración de cloro activo durante solo 24 horas


Assuntos
Humanos , Anti-Infecciosos/análise , Infecções por Coronavirus/prevenção & controle , Pneumonia Viral/prevenção & controle , Pandemias/prevenção & controle , Hipoclorito de Sódio/análise , Cloro/análise , Água Potável/análise , Organização Mundial da Saúde , Antibacterianos/análise
7.
Environ Monit Assess ; 193(1): 10, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33319333

RESUMO

The present work shows the evaluation of the decay of free residual chlorine in several public swimming pools in the city of Medellín, observing that a decrease in residual chlorine does occur. Some factors accelerate the decrease in the concentration of free residual chlorine in recreational water, such as the number of bathers in the pool, the pH, and the temperature of the water. For this reason, the concentration of the disinfectant rapidly decreases to an extent that the health of swimmers could be put at risk. The Authority of Health of Medellín carries out inspection, surveillance and quality control activities of water for recreational use. These purposes of these include guaranteeing the reduction of risk factors to the health of the users of said pools.


Assuntos
Desinfetantes , Piscinas , Cloro/análise , Colômbia , Desinfetantes/análise , Monitoramento Ambiental , Natação
8.
J Parasitol ; 106(6): 742-754, 2020 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-33326586

RESUMO

Three species of adult hard tick (Ixodidae) were examined with scanning electron microscopy-energy dispersive X-ray spectroscopy to obtain elemental profiles of their exoskeletons and determine the presence of trace elements. The scutum, tarsal claws, chelicerae, and hypostome were examined on females and males of Amblyomma americanum, Dermacentor variabilis, and Ixodes scapularis. The only trace elements present included chlorine, calcium, and sodium. Chlorine was the most abundant trace element and occurred in all examined regions. The chelicerae generally possessed the highest weight percentages of Cl (up to 11.32 ± 1.36%) across all 3 species, although high weight percentages of Cl (up to 8.78 ± 2.77%) were also present in the hypostome teeth of most specimens. All 3 trace elements were present in the hypostome of A. americanum and I. scapularis, but Ca and Na appear to be absent from the teeth of D. variabilis. In general, there were few differences in the elemental profiles of the exoskeletons between the sexes of any species. This study confirms the presence of alkali metals (Na) and alkaline earth metals (Ca) in adult ticks, which are also common in other arachnids; however, the absence of transition metals such as zinc from the exoskeletons of ticks is uncommon and only shared with species of Ricinulei and Opiliones.


Assuntos
Ixodidae/química , Oligoelementos/análise , Exoesqueleto/química , Exoesqueleto/ultraestrutura , Animais , Cálcio/análise , Cloro/análise , Feminino , Ixodidae/anatomia & histologia , Ixodidae/ultraestrutura , Masculino , Massachusetts , Microscopia Eletrônica de Varredura , Missouri , New Hampshire , Sódio/análise , Espectrometria por Raios X , Oligoelementos/química
9.
Ecotoxicol Environ Saf ; 205: 111343, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32979801

RESUMO

Taste and odor (T&O) problem in water is one of the main obstacles to improve the quality of drinking water, and efficient water treatment processes are urgently needed to control T&O compounds. Ultraviolet-mediated peroxymonosulfate (UV/PMS) diminution of trichloroanisole (TCA) in water was investigated in this paper. The treatment of 2,3,6-trichloroanisole (2,3,6-TCA) by three advanced oxidation processes (UV, UV/H2O2 and UV/PMS) was compared, and UV/PMS stood out. SO4•- and HO• were produced in the UV/PMS, and their specific contributions to 2,3,6-TCA oxidation were investigated. The competitive kinetic model was applied to determine the second-order reaction rate between 2,3,6-TCA and SO4•- or HO•. The products of 2,3,6-TCA generated in UV/PMS were analyzed with gas chromatography/high resolution-mass spectrometry (GC/HR-MS), and the degradation mechanism was proposed. The effects of water matrices (chloride, bicarbonate and humic acid) on UV/PMS performance were studied, and the decontamination of 2,3,6-TCA in real water was carried out. The disinfection byproducts (DBPs) alteration from 2,3,6-TCA by UV/PMS - chlorination treatment was explored. Overall, UV/PMS can effectively deal with the T&O pollution of TCA in water.


Assuntos
Anisóis/química , Peróxidos/química , Poluentes Químicos da Água/química , Cloro/análise , Desinfecção , Halogenação , Substâncias Húmicas/análise , Peróxido de Hidrogênio/química , Cinética , Oxirredução , Raios Ultravioleta , Água , Poluentes Químicos da Água/análise , Purificação da Água/métodos
10.
Chemosphere ; 254: 126872, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957284

RESUMO

The distribution of 20 personal care products (PCPs), including seven preservatives, six UV filters, five anticorrosion agents, and two antimicrobials, were determined in 40 swimming pools using solid phase extraction followed by liquid chromatography-tandem mass spectrometry. Among 14 targets detected, 1H-benzotriazole and triclocarban were observed in all samples. The detected concentrations of preservatives, UV filters, anticorrosion agents, and antimicrobials were in the ranges of not detected (nd)-179 ng L-1, nd-289 ng L-1, nd-58.4 ng L-1, and nd-56.9 ng L-1, respectively. The presence of preservatives, UV filters and antimicrobials in pool waters might be mainly brought in by human activities while anticorrosion agents were mainly from the source water. Furthermore, the concentrations of methylparaben, ethylparaben, 1H-benzotriazole, 5-methyl-1H-benzotriazole, 5-chloro-1H-benzotriazole, and 5,6-dimethyl-1H-benzotriazole in indoor pools were found higher than those in outdoor pools. The longer opening time and weaker light intensity for indoor pools might cause the difference. The redundancy analysis showed significantly negative correlations between the concentrations of parabens and the contents of residual chlorine in the pool waters. A higher chlorine residue may promote the decomposition of parabens. Health risk assessment showed that skin penetration would be the main approach for the intake of PCPs by swimmers while swimming. Compared with the non-athletic swimmers, the athletic swimmers might be more sensitive, but the health risks for both groups of swimmers could be negligible.


Assuntos
Cosméticos/análise , Monitoramento Ambiental , Poluentes Químicos da Água/análise , Carbanilidas , Cloro/análise , Cromatografia Líquida , Humanos , Parabenos , Medição de Risco , Extração em Fase Sólida , Natação , Piscinas , Triazóis
11.
Int. j. morphol ; 38(4): 1112-1119, Aug. 2020. tab, graf
Artigo em Inglês | LILACS | ID: biblio-1124903

RESUMO

Monosodium glutamate (MSG) is a flavor enhancer widely used in the food industry, with obesogenic properties, in addition to causing alterations in the oral cavity. The aim of the study was to observe the morphofunctional changes in the parotid gland after the administration of MSG in rats. 18 newborn male Sprague Dawley rats were used, divided into three groups (Control group; MSG1 group: 4 mg/g weight of monosodium glutamate, 5 doses, kept for 8 weeks, and MSG2 group: 4 mg/g weight of MSG, 5 doses, kept for 16 weeks). The body mass index (BMI) was calculated, and the salivary flow, pH, a-amylase activity, Na, Cl, K and Ca were analyzed by quantitative analysis. After euthanasia by ketamine/xylazine overdose, parotid volume was analyzed and stereology was performed. MSG administration caused an increase in BMI and a decrease in parotid volume as well as a reduction in salivary flow and pH and an increase in a-amylase activity, also increasing the salivary sodium and chlorine levels. Alterations in the normal stereological parameters of the gland were observed. Exposure to MSG caused morphofunctional alterations at parotid gland.


El glutamato monosódico (MSG), es un potenciador del sabor ampliamente utilizado en la industria alimentaria. Diversos estudios han propuesto la relación entre éste y el desarrollo de obesidad, además de provocar alteraciones en la cavidad oral. El objetivo del estudio fue observar los cambios morfofuncionales a nivel de la glándula parótida, posterior a la administración de MSG en ratas. Se utilizaron 18 ratas neonatas Sprague Dawley machos, divididas en tres grupos según su tiempo de exposición y dosis a MSG (Grupo Control, Grupo MSG1: 4 mg/g peso de glutamato monosódico, 5 dosis, mantenidas 8 semanas, Grupo MSG2: 4 mg/g peso de MSG, 5 dosis, mantenidas 16 semanas. Fue calculado el índice de masa corporal (BMI), además de ser analizado el flujo salival, pH, actividad de α-amilasa, y Na, Cl, K y Ca mediante análisis semicuantitativo. Luego de la eutanasia por sobredosis de ketamina/xilasina, las glándulas parótidas fueron extraídas y analizado su volumen y fueron procesadas para histología, y estudio estereológico. La administración de MSG causó aumento en BMI y disminución del volumen parotídeo, además de disminución del flujo y pH salival, así como aumento en actividad de la a-amilasa, aumentando además los niveles de sodio y cloro salival. Fueron observadas alteraciones a nivel de los parámetros estereológicos normales de la glándula. La exposición a MSG causó alteraciones morfofuncionales a nivel parotídeo, observándose una disminución del volumen de la glándula, acompañado de alteraciones en el adenómero y conductos estriados de la glándula, implicados en la producción, secreción y modificación de la saliva, la cual se vio alterada, en el flujo, pH, y en sus componentes.


Assuntos
Animais , Masculino , Ratos , Glândula Parótida/efeitos dos fármacos , Glutamato de Sódio/administração & dosagem , Aromatizantes/administração & dosagem , Saliva/química , Sódio/análise , Glutamato de Sódio/farmacologia , Fatores de Tempo , Índice de Massa Corporal , Cloro/análise , Análise de Variância , Ratos Wistar , alfa-Amilases/análise , Aromatizantes/farmacologia , Concentração de Íons de Hidrogênio
12.
Environ Monit Assess ; 192(8): 516, 2020 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-32666262

RESUMO

Applying a desirable disinfestation process is necessary to control the pathogenic microorganisms in the swimming pools and prevent both dermal and intestinal effects. Therefore, the present study was conducted to compare the bacterial community and diversity in the two swimming pools disinfected by the chlorine and ozone (O3)-chlorine processes. A total of 24 samples were taken from the two swimming pools in three distinct seasons to analyze the bacterial and physico-chemical indicators. Culture and molecular methods were used to evaluate the microbial quality. Two sets of sample taken from the pools with the maximum swimmer load in the summer were investigated by the next-generation sequencing (NGS) technique. In total, 410 and 406 bacterial species were identified in the chlorine- and ozone-chlorine-disinfected pools, respectively. Among the eight dominant bacterial species in each swimming pool, Pseudomonas alcaliphila, Pseudomonas stutzeri, and Pseudomonas acnes were common species between the two studied pools. Oleomonas sagaranensis (350 reads/18593), Staphylococcus caprae (302 reads /18593), and Anaerococcus octavius (110 reads/18593) were among the dominant bacteria in the chlorine-disinfected pool. Bacterial diversity was lower in the ozone-chlorine-disinfected pool than the other one, and the highest bacterial sequencing belonged to the genus Pseudomonas (85.79%). Results showed that water quality of in O3-chlorine-disinfected pool was more desirable than the chlorine-disinfected pool. Molecular methods along with conventional culture methods would be advantageous for microbial assessment in the swimming pools.


Assuntos
Desinfetantes/análise , Ozônio , Piscinas , Acetobacteraceae , Cloro/análise , Desinfecção , Monitoramento Ambiental , Firmicutes , Irã (Geográfico) , Pseudomonas , Staphylococcus , Microbiologia da Água
13.
Chemosphere ; 261: 127531, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32707319

RESUMO

Halogenated acetaldehydes (HALs) are widely considered to be the third largest group of identified disinfection by-products (DBPs) by weight in drinking water. In this study, we evaluated various scenarios for the domestic handling of drinking water and their effects on HALs. Two drinking water systems (DS1 and DS2) were selected for this case study. First, tap water samples that were collected in DS1 at different time and from different locations were subjected to three domestic handling scenarios: boiling, domestic filtration using a point-of-use device with a new filter followed by refrigeration, and refrigeration in a covered glass pitcher. In the last two scenarios, the maximum storage (refrigeration) time was 24 h. Second, two water samples each from DS1 and DS2 were collected to investigate the effects that heating water to different temperatures has on HALs. According to the results, boiling the water effectively removed most HALs except dichloroacetaldehyde (DCAL), which increased. In contrast to the variable behaviors of HALs after boiling, all HALs were consistently and significantly reduced by domestic filtration. However, the overall removal efficiency of HALs from filtration (65%) was considerably lower than that from boiling (85%). Finally, refrigeration had no significant impact on the overall concentration of total HALs. However, chloral hydrate levels increased in unfiltered water after refrigeration, likely due to the reaction of chlorine residuals and precursors present in water. Therefore, boiling and domestic filtering of tap water may be recommended for the removal of HALs prior to consuming tap water.


Assuntos
Acetaldeído/química , Água Potável/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Acetaldeído/análogos & derivados , Acetaldeído/análise , Cloro/análise , Desinfetantes/análise , Desinfecção/métodos , Água Potável/análise , Filtração/métodos , Halogenação , Abastecimento de Água
14.
PLoS One ; 15(6): e0233239, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32516315

RESUMO

Foodborne contamination and associated illness in the United States is responsible for an estimated 48 million cases per year. Increased food demand, global commerce of perishable foods, and the growing threat of antibiotic resistance are driving factors elevating concern for food safety. Foodborne illness is often associated with fresh-cut, ready-to-eat produce commodities due to the perishable nature of the product and relatively minimal processing from farm to the consumer. The research presented here optimizes and evaluates the utility of microfluidic droplets, also termed ultra-miniaturized bioreactors, for rapid detection of viable Salmonella enterica ser. Typhimurium in a shredded lettuce wash water acquired from a major Mid-Atlantic produce processing facility (denoted as Producer) in the U.S. Using a fluorescently-labeled anti-S. Typhimurium antibody and relative fluorescence intensities, paired with in-droplet incubation, S. Typhimurium was detected and identified with 100% specificity in less than 5 h. In initial optimization experiments using S. Typhimurium-spiked sterile water, the relative fluorescence intensity of S. Typhimurium was approximately two times that of the observed relative intensities of five non-S. Typhimurium negative controls at 4-h incubation in droplets containing Rappaport-Vasiliadis (RV) broth at 37°C: relative fluorescence intensity for S. Typhimurium = 2.36 (95% CI: 2.15-2.58), Enterobacter aerogens 1.12 (95% CI: 1.09-1.16), Escherichia coli 700609 = 1.13 (95% CI: 1.09-1.17), E. coli 13706 1.13 (95% CI: 1.07-1.19), E. coli 700891 1.05 (95% CI: 1.03-1.07) and Citrobacter freundii 1.04 (95% CI: 1.03-1.05). S. Typhimurium- and E. aerogens-spiked shredded lettuce wash waters acquired from the Producer were then incubated 4 h in-droplet at 37°C with RV broth. The observed relative fluorescence of S. Typhimurium was significantly higher than that of E. aerogens, 1.56 (95% CI: 1.42-1.71) and 1.10 (95% CI: 1.08-1.12), respectively. While further optimization focusing on compatible concentration methodologies for highly-dilute produce water samples is needed, this application of droplet microfluidics shows great promise in dramatically shortening the time necessary-from days to hours-to confirm viable bacterial contamination in ready-to-eat produce wash waters used throughout the domestic and international food industry.


Assuntos
Microbiologia de Alimentos/métodos , Doenças Transmitidas por Alimentos/prevenção & controle , Técnicas Analíticas Microfluídicas/métodos , Cloro/análise , Citrobacter freundii , Contagem de Colônia Microbiana , Desinfetantes , Escherichia coli O157 , Contaminação de Alimentos/análise , Manipulação de Alimentos/métodos , Indústria de Processamento de Alimentos , Doenças Transmitidas por Alimentos/microbiologia , Microfluídica/métodos , Salmonella typhimurium
15.
Chemosphere ; 251: 126674, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32359720

RESUMO

Dimensionally stable anodes (DSA) have been widely used to degrade organic compounds because these surfaces promote the electrogeneration of active chlorine species in the bulk of the solution, as well as in the vicinity of the anode when NaCl is used as supporting electrolyte. In this work, the nanoparticles synthesis of IrO2 and RuO2 was performed to obtain two types of DSA electrodes named Class I and II to degrade oxamic acid. For Class I and II DSA, the nanoparticles used were synthesized separately and in the same reaction medium, respectively. Electrolysis were carried out in an open cylindrical cell without division at 25 °C, DSAs were used as anodes and a stainless-steel electrode as cathode, both elements have a geometric area of 2.8 cm2 immersed in 0.05 mol L-1 of NaCl or Na2SO4 and a current density of 3 mA cm-2 was applied for 6 h. Active chlorine species generated in the absence of oxamic acid in NaCl were also detected and quantified through ion chromatography. In Na2SO4 there was no degradation of the compound, but in NaCl the oxamic acid concentration reaching 85% with Class I DSA. The same tendency is observed in mineralization, in which Class I DSA allowed reaching a CO2 transformation close to 73%. The difference in the results occurs because with Class I DSA, more hypochlorite is generated than with Class II and therefore there is a larger amount of oxidizing species in the solution that enables the degradation and mineralization of oxamic acid.


Assuntos
Irídio/química , Modelos Químicos , Ácido Oxâmico/química , Compostos de Rutênio/química , Cloro/análise , Eletrodos , Eletrólise/métodos , Nanopartículas , Oxirredução , Poluentes Químicos da Água/análise
16.
Am J Trop Med Hyg ; 103(2): 646-651, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32458780

RESUMO

On October 6, 2017, the Zambia Ministry of Health declared a cholera outbreak in Lusaka. By December, 1,462 cases and 38 deaths had occurred (case fatality rate, 2.6%). We conducted a case-control study to identify risk factors and inform interventions. A case was any person with acute watery diarrhea (≥ 3 loose stools in 24 hours) admitted to a cholera treatment center in Lusaka from December 16 to 21, 2017. Controls were neighbors without diarrhea during the same time period. Up to two controls were matched to each case by age-group (1-4, 5-17, and ≥ 18 years) and neighborhood. Surveyors interviewed cases and controls, tested free chlorine residual (FCR) in stored water, and observed the presence of soap in the home. Conditional logistic regression was used to generate matched odds ratios (mORs) based on subdistricts and age-groups with 95% CIs. We enrolled 82 cases and 132 controls. Stored water in 71% of case homes had an FCR > 0.2 mg/L. In multivariable analyses, those who drank borehole water (mOR = 2.4, CI: 1.1-5.6), had close contact with a cholera case (mOR = 6.2, CI: 2.5-15), and were male (mOR = 2.5, CI: 1.4-5.0) had higher odds of being a cholera case than their matched controls. Based on these findings, we recommended health education about household water chlorination and hygiene in the home. Emergency responses included providing chlorinated water through emergency tanks and maintaining adequate FCR levels through close monitoring of water sources.


Assuntos
Cloro/análise , Cólera/epidemiologia , Água Potável/química , Saneamento/estatística & dados numéricos , Sabões , Purificação da Água/estatística & dados numéricos , Abastecimento de Água/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Criança , Pré-Escolar , Epidemias , Feminino , Educação em Saúde , Humanos , Higiene , Lactente , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Razão de Chances , Fatores de Risco , Poços de Água , Adulto Jovem , Zâmbia/epidemiologia
17.
Environ Int ; 138: 105665, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32200313

RESUMO

Volatile and hazardous compounds are formed during the chlorination of pool water. Monitoring components in the air, such as the four trihalomethanes; chloroform, dichlorobromomethane, dibromochloromethane and bromoform (tTHM), is challenging. Carbon dioxide (CO2) sensors are used for controlling air quality in different buildings and can be installed in ventilation systems for continuous surveillance and monitoring purposes. However, such sensors are not used in indoor swimming facilities. In this study, samples of tTHM and CO2 were collected and analysed, along with other air and water quality parameters such as combined chlorine, to evaluate whether CO2 sensors could be used to explain the observed variability in the tTHM concentration in an indoor swimming facility and thereby reduce the exposure of individuals utilising the pool to tTHM. Random intercept models were built for the tTHM and CO2 concentrations, respectively, and the results show that the relationships between combined chlorine in the water, CO2 in the air and number of occupants explain 52% of the variability in tTHM. The correlation between occupancy and CO2 concentration (ρ = 0.65, p ≤ 0.01) suggests that CO2 sensors should be used so that the air supply corresponds to the demand of the users.


Assuntos
Poluição do Ar em Ambientes Fechados , Piscinas , Dióxido de Carbono , Cloro/análise , Clorofórmio/análise , Humanos , Trialometanos/análise
18.
Ecotoxicol Environ Saf ; 194: 110339, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32143103

RESUMO

Serum and breast milk are both important biological samples to evaluate body burden of dioxin-like compounds which include polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs). We collected maternal serum at early pregnancy, and breast milk at 3-8 weeks after delivery from 55 mothers living in Beijing, China, and measured 29 dioxin-like compounds in these samples. The sampling intervals in this study were extended up to 10 months to analyze differences of contents between serum and breast milk under long sampling intervals. The results showed that mean TEq level of PCDD/Fs in serum (9.8 pg TEq g-1 lipid) was 1.7 times higher than that in milk (4.5 pg TEq g-1 lipid), while the TEq concentrations of dl-PCBs in serum (1.2 pg TEq g-1 lipid) was significantly lower than that in milk (2.0 pg TEq g-1 lipid). There were only two congeners, OCDD (r = 0.32) and PCB105 (r = 0.33), the correlations of which between serum and milk were significant. The differences in distributions of congeners in serum and milk might be influenced by number of chlorine substituents and structures of congeners. In addition, maternal age and BMI were positively and negatively correlated with mass concentrations of dioxin-like compounds in milk and serum respectively. These results suggest that, compared with serum, it is limited to use breast milk to assess long-term exposure for the wider population.


Assuntos
Dioxinas/metabolismo , Poluentes Ambientais/metabolismo , Leite Humano/metabolismo , Pequim , Benzofuranos/análise , Carga Corporal (Radioterapia) , China , Cloretos/análise , Cloro/análise , Dibenzofuranos , Dibenzofuranos Policlorados/análise , Dioxinas/análise , Dioxinas/sangue , Poluentes Ambientais/análise , Poluentes Ambientais/sangue , Feminino , Humanos , Lipídeos/análise , Exposição Materna/estatística & dados numéricos , Leite Humano/química , Bifenilos Policlorados , Dibenzodioxinas Policloradas/análise , Gravidez
19.
J Appl Microbiol ; 129(2): 453-464, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32012390

RESUMO

AIMS: The study established the inactivation kinetic parameters of an Acanthamoeba cyst isolate subjected to heating and chlorination. METHODS AND RESULTS: A strain of Acanthamoeba was isolated and purified from an area surrounding a pilot food plant. Mature cysts (14 days) were subjected to heat inactivation studies at 71, 76, 81, 86 and 91°C; and chlorination at 100, 200, 300, 400 and 500 ppm. The decimal reduction times (D-values) at 71, 76, 81, 86 and 91°C were 18·31, 9·26, 7·35, 4·52 and 1·81 min respectively. The calculated thermal resistance constant (z-value) was 21·32°C (R2  = 0·96-0·97). The D-value in 100, 200, 300, 400 and 500 ppm chlorine-treated water were 47·17, 25·06, 24·51, 23·70 and 18·55 min respectively. The chlorine resistance constant (z-value) was 1179 ppm chlorine (R2  = 0·65-0·74). CONCLUSIONS: Results demonstrated high resistance of the isolated Acanthamoeba cysts towards the common methods applied in ensuring food and food processing environment sanitation. SIGNIFICANCE AND IMPACT OF THE STUDY: The resistance parameters of the test organisms established in this study may be used in the establishment of Sanitation Standard Operating Procedures (SSOPs), which are often based on inactivation of bacteria. These SSOPs could render better protection to food and food processing environments.


Assuntos
Acanthamoeba/crescimento & desenvolvimento , Cloro/metabolismo , Temperatura Alta , Encistamento de Parasitas/fisiologia , Purificação da Água/métodos , Acanthamoeba/metabolismo , Adaptação Fisiológica , Cloro/análise , Inocuidade dos Alimentos , Microbiologia do Solo , Água/química , Microbiologia da Água , Purificação da Água/normas
20.
J Chromatogr A ; 1616: 460844, 2020 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-31952814

RESUMO

The aim of this study was to develop a statistical model based on a set of intuitive topological descriptors that will help to determine the influence of the polychlorinated biphenyls (PCBs) structural features on the chromatographic behavior of these analytes in a variety of gas chromatographic stationary phases, including the highly polar ionic liquid (IL)-based SLB-IL76 and SLB-IL60 columns. The model was developed using the stepwise multiple linear regression method, and constructed through several levels of increasing complexity to make evident the relative influence of the selected descriptors. The proposed model was easy to implement and provided similar satisfactory results irrespective of the dependent variables used (i.e., retention index or retention time) or the chromatographic conditions applied (i.e., pseudo-isotherm and programmed temperature) for IL-based phases. The model also allowed the correct prediction of the elution order of selected PCBs in these and other less polar phases evaluated (i.e., SW-10, DB-17, ZB-5 and HT-8). To our knowledge, this is the first models based on topological descriptors described in the literature that provided a satisfactory fitting of the PCB behavior in IL-based phases. Our results indicated that the mechanism governing the chromatographic separation of PCBs in these highly polar columns showed significant differences compared with those observed in other less polar stationary phases.


Assuntos
Cromatografia Gasosa/métodos , Líquidos Iônicos/química , Bifenilos Policlorados/análise , Cloro/análise , Modelos Estatísticos , Análise de Componente Principal , Reprodutibilidade dos Testes
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