Chlorination By-products Research Articles

Dichloroacetonitrile induces oxidative stress and developmental apoptotic imbalance in mouse fetal brain

Dichloroacetonitrile (DCAN) is one of the disinfection by-products of chlorination of drinking water. Limited mechanistic studies exist on the developmental toxicity of haloacetonitriles (HANs). The present study was designed to investigate the potential adverse effects of maternal exposure to DCAN on mouse fetal brain. Based on initial dose–response experiment, DCAN (14 mg/kg/day) was administered orally to pregnant mice at gestation day (GD) 6, till GD 15. Maternal exposure to DCAN resulted in redox imbalance in fetal cortex and cerebellum, characterized by significant decrease in reduced glutathione (GSH), and elevation of malondialdehyde (MDA) level and superoxide dismutase (SOD) activity. Further, DCAN induced apoptosis indicated by significant enhancement of DNA fragmentation and active caspase-3 level in fetal cortex and cerebellum. Neuronal degeneration was indicated by positive cupric silver staining. In conclusion, maternal exposure to DCAN adversely affects mouse fetal brain as evidenced by induction of oxidative stress, apoptotic imbalance and neurodegeneration.

Removal of estrogens and estrogenicity through drinking water treatment

Estrogenic compounds have been shown to be present in surface waters, leading to concerns over their possible presence in finished drinking waters. In this work, two in vitro human cell line bioassays for estrogenicity were used to evaluate the removal of estrogens through conventional drinking water treatment using a natural water. Bench-scale studies utilizing chlorine, alum coagulation, ferric chloride coagulation, and powdered activated carbon (PAC) were conducted using Ohio River water spiked with three estrogens, 17β-estradiol, 17α-ethynylestradiol, and estriol. Treatment of the estrogens with chlorine, either alone or with coagulant, resulted in approximately 98% reductions in the concentrations of the parent estrogens, accompanied by formation of by-products. The MVLN reporter gene and MCF-7 cell proliferation assays were used to characterize the estrogenic activity of the water before and after treatment. The observed estrogenic activities of the chlorinated samples showed that estrogenicity of the water was reduced commensurate with removal of the parent estrogen. Therefore, the estrogen chlorination by-products did not contribute appreciably to the estrogenic activity of the water. Coagulation alone did not result in significant removals of the estrogens. However, addition of PAC, at a typical drinking water plant dose, resulted in removals ranging from approximately 20 to 80%.

Derivation of predicted no effect concentrations (PNEC) for 2,4,6-trichlorophenol based on Chinese resident species

2,4,6-Trichlorophenol (2,4,6-TCP) is a common chemical intermediate and a by-product of water chlorination and combustion processes, and is a priority pollutant of the aquatic environment in many countries. Although information on the toxicity of 2,4,6-TCP is available, there is a lack of information on the predicted no-effect concentration (PNEC) of 2,4,6-TCP, mainly due to the shortage of chronic and site-specific toxicity data. In the present study, acute and sub-chronic toxicity of 2,4,6-TCP on six different resident Chinese aquatic species were determined. PNEC values were calculated and compared by use of two approaches: assessment factor (AF) and species sensitivity distribution (SSD). Values for acute toxicity ranged from 1.1mgL−1 (Plagiognathops microlepis) to 42mgL−1 (Corbicula fluminea) and the sub-chronic no observed effect concentrations (NOECs) ranged from 0.05mgL−1 (Mylopharyngodon piceus) to 2.0mgL−1 (C. fluminea). PNECs obtained by the assessment factor approach with acute (AF=1000, 0.001mgL−1) or chronic (AF=10, 0.005mgL−1) toxicity data were one order of magnitude less than those from SSD methods (0.057mgL−1). PNEC values calculated using SSD methods with a 50% certainty for 2,4,6-TCP was less than those obtained by use of the USEPA recommend final chronic value (FCV) method (0.097mgL−1) and the one obtained by use of the USEPA recommend acute-to-chronic (ACR) methods (0.073mgL−1). PNECs derived using AF methods were more protective and conservative than that derived using SSD methods.

POPULATION IMPACT OF CHLORINATION BY-PRODUCTS EXPOSURE ON INTRA-UTERINE GROWTH RETARDATION OCCURENCE

Background and Aims: Chlorination By-Products (CBPs) exposure during pregnancy has been associated with intra-uterine growth retardation (IUGR). The objective of this study was to estimate the pote...

CHLORINATION DISINFECTION BY-PRODUCTS IN CANADIAN DRINKING WATER AND BRAIN CANCER RISK

Background and Aims: The etiology of brain cancers remains poorly understood. The study of brain cancer and chlorination disinfection by-products (CDBPs) in drinking water with the best exposure assessment suggested increased risk of brain cancer associated with long-term exposure to CDBPs. Our aim was to replicate this high-quality study in Canada. Methods: We conducted a population-based case-control study of 1009 incident cases of primary brain cancer and 5039 controls in eight Canadian provinces to assess the impact of chlorination disinfection by-products in Canadian drinking water on brain cancer risk. Mailed questionnaires were used to collect a lifetime residential history, source of drinking water, and other risk factors. We estimated the exposure to chlorination by-products in drinking water by combining questionnaire data with historical data on by-products levels for more than 600 water treatment plants. We included 684 cases and 3805 controls in the analysis who had exposure information for at least 70% of the period 5 to 45 years period prior to interview. Results: Risk was not related to lifetime average trihalomethane (THM) levels or years of exposure to THMs or to higher levels or longer duration of exposure to bromodichloromethane (BDCM). We observed no association with more years of exposure to THM at 3 levels: THM>20, >40 and >60 μg/l. The results for women and men were similar to that for both genders combined. Stratified analyses by histology subtype of brain cancer did not demonstrate any consistent relationship of brain cancer risk with either exposure to higher levels of THM or DBCM, or longer years of exposure to THM or DBCM, although increased risk was observed for some categories of exposure years for glioblastoma and astrocytoma tumors. Conclusions: Our study does not support the hypothesis that chlorination disinfection by-products play a significant role in the etiology of brain cancer.

Removal of 17β-estradiol (E2) and its chlorination by-products from water and wastewater using non-imprinted polymer (NIP) particles

Endocrine disrupting compounds and their chlorination by-products are two classes of emerging contaminants. Surface water and wastewater treatment technologies have limitations in removing these contaminants. This study evaluated the ability of non-imprinted polymer particles (NIP) to remove the endocrine disruptor 17beta-estradiol (E2) and its chlorination by-products from water and wastewater. NIP effectively removed 98% of 10 mg/L E2 from wastewater. NIP were also effective in removing chlorination by-products of E2 by 84.9% after 10 mg/L E2 in water was chlorinated at 5 mg/L. In the presence of 5 mg/L humic acid, NIP were able to achieve removal of 10 mg/L E2 by greater than 99.9%. Furthermore, after chlorination of 10 mg/L E2 and 5 mg/L humic acid at 10 mg/L chlorine, NIP were also able to remove the chlorination by-products formed as well as the remaining E2 by greater than 99.9%. The presence of 5 mg/L humic acid did not adversely affect the adsorption efficiency. The results of this research indicate that NIPs have good potential as a final treatment step for surface water and wastewater treatment.

Determinants of chlorination by-products in indoor swimming pools

Water and air quality of fifteen swimming pools using chlorine disinfection was measured during eight sampling campaigns in Rennes, France. Concentrations of trihalomethanes (THMs) and trichloramine (NCl(3)) in air as well as concentrations of parameters, including total organic carbon (TOC), chlorine (free, combined and total), pH, Kjeldhal nitrogen (KN), chloride ions and THMs in water and air temperature, were measured. Water and air samples were collected during 3h in the morning and afternoon, during high and low attendance days, in summer and winter. Data analysis was perfomed by multivariate ordinary least square (OLS) and quantile (QR) regressions, from both data quality and other parameters such as the ratio between the number of visitors and the volume of water available V/W, the proportion of air re-circulated and the number of swimmers during sampling. The geometric means (GM±95% CIs) of the sum of THMs (TTHM) and NCl(3) in air were 74.9±6.7 μg/m(3) and 190±10 μg/m(3), respectively. As expected, concentrations of TTHM in air were correlated to concentrations of TTHM in water. Concentrations of TTHM and NCl(3) in air measured in winter were significantly higher than in summer, depicting that low air exchange rate in winter lead to accumulation of pollutants. NCl(3) (especially at higher quantiles) and TTHM concentrations in air were associated to the number of swimmers. NCl(3) was also linked to air temperature and pH. Moreover TTHM and NCl(3) in air seemed to be affected by additional determinants including the volume of hall and the ratio V/W. In a process of reducing exposure, the OLS regression provides useful information on key parameters influencing concentrations of THMs and NCl(3) in indoor swimming pools. In addition, QR allows identifying factors associated to elevated levels of contamination.

Fate of toxic cyanobacterial cells and disinfection by-products formation after chlorination

Drinking water sources in many regions are subject to proliferation of toxic cyanobacteria (CB). Chlorination of source water containing toxic cyanobacterial cells for diverse treatment purposes might cause cell damage, toxin release and disinfection by-products (DBP) formation. There is limited information available on chlorination of different toxic CB cells and DBP formation potentials. This work: (1) determines the extent of lysis and toxins/taste and odor compound release in chlorinated natural water from CB cells (Anabaena circinalis, Microcystis aeruginosa, Cylindrospermopsis raciborskii, and Aphanizomenon issatsckenka) from laboratory cultures and natural blooms; (2) assesses the rates of oxidation of toxins by free chlorine under environmental conditions; (3) studies the DBP formation associated with the chlorination of CB cell suspensions. With chlorine exposure (CT) value of <4.0 mg min/L >60% cells lost viability causing toxin release. Cell membrane damage occurred faster than oxidation of released toxins. Kinetic analysis of the oxidation of toxins in natural water revealed significant differences in their susceptibility to chlorine, saxitoxins being the easiest to oxidize, followed by cylindrospermopsin and microcystin-LR. Furthermore, concentrations of trihalomethanes and haloacetic acids (<40 μg/L) and N-nitrosodimethylamine (<10 ng/L) as chlorination by-products were lower than the guideline values even at the highest CT value (220 mg min/L). However, the DBP concentrations in environmental bloom conditions with very high cell numbers were over the guideline values.

Potencialidades do uso do ozônio no processamento de alimentos

Ozone is a colorless and unstable gas with pungent smell and partially soluble in water, which is characterized by its high oxidant power. It is a strong agent disinfectant with high power germicidal properties acting in the inactivation of a wide variety of pathogenic organisms, including bacteria, virus and protozoa, presenting a germicidal efficiency that exceeds chlorine. Ozonization has become well-known in recent decades due to implementation of standards increasingly restrictive concerning the by-products of chlorination. Unlike chlorine, ozone do not form halogenated compounds with organic matter. However, it may form several other organic and inorganic. In the food industry, ozone can be use in sanitization processes of equipments and surfaces, as well as in the direct use on foodstuff in order to inactivate microorganisms and to extend shelf-life of food products.

Simultaneous reduction of by-products of chlorine dioxide and chlorine using Fe(II)–Al(III) coagulant mixture

Ferrous iron has been considered very useful for removal of chlorite, a by-product of chlorine dioxide. However, a serious problem can occur associated with high residual iron concentrations in water after Fe(II) treatment, especially at weak acidic condition (pH 6), having a higher capacity of chlorite reduction. Simultaneous removal of chlorite, dissolved iron, and humic acids was achieved with a Fe(II) –Al(III) (1:5) coagulant mixture. Moreover, a significant reduction of chlorine by-products formed after subsequent post chlorination was observed. The by-products of chlorine dioxide and chlorine could be dramatically reduced by the simple addition of the coagulant mixture without the additional problem of dissolved iron.

Chlorination byproducts induce gender specific autistic-like behaviors in CD-1 mice

In 2000, the Agency for Toxic Substances and Disease Registry (ATSDR) released a report concerning elevated autism prevalence and the presence water chlorination byproducts in the municipal drinking water supply in Brick Township, New Jersey. The ATSDR concluded that it was unlikely that these chemicals, specifically chloroform, bromoform (Trihalomethanes; THMs) and tetrachloroethylene (Perchloroethylene; PCE) had contributed to the prevalence of autism in this community based upon correlations between timing of exposure and/or concentration of exposure. The ATSDR conclusion may have been premature, as there is no conclusive data evidencing a correlation between a particular developmental time point that would render an individual most susceptible to toxicological insult with the development of autism. Therefore, it was our aim to determine if these chemicals could contribute to autistic like behaviors. We found that males treated with THMs and PCE have a significant reduction in the number of ultrasonic vocalizations (USVs) emitted in response to maternal separation, which are not attributed to deficits in vocal ability to or to lesser maternal care. These same males also show significantly elevated anxiety, an increase in perseverance behavior and a significant reduction in sociability. The sum of our data suggests that male, but not female mice, develop autistic like behaviors after gestational and postnatal exposure to the aforementioned chemical triad via drinking water. We believe development of such aberrant behaviors likely involves GABAergic system development.

Occurrence and treatment of wastewater-derived organic nitrogen

Dissolved organic nitrogen (DON) derived from wastewater effluent can participate in reactions that lead to formation of nitrogenous chlorination by-products, membrane fouling, eutrophication, and nitrification issues, so management of DON is important for both wastewater reuse applications and nutrient-sensitive watersheds that receive discharges from treated wastewater. This study documents DON occurrence in full-scale water/wastewater (W/WW) treatment plant effluents and assesses the removal of wastewater-derived DON by several processes (biodegradation, coagulation, softening, and powdered activated carbon [PAC] adsorption) used for advanced treatment in wastewater reuse applications. After varying levels of wastewater treatment, the dominant aqueous nitrogenous species shifts from ammonia to nitrate after aerobic processes and nitrate to DON in tertiary treatment effluents. The fraction of DON in total dissolved nitrogen (TDN) accounts for at most 52% in tertiary treated effluents (median = 13%) and 54% in surface waters impacted by upstream wastewater discharges (median = 31%). The 5-day biodegradability/bioavailability of DON (39%) was higher, on average, than that of dissolved organic carbon (DOC, 26%); however, upon chlorination, the DON removal (3%) decreased significantly. Alum coagulation (with ≥8 mg/L alum per mg/L DOC) and lime softening (with pH 11.3–11.5) removed <25% of DON and DOC without selectivity. PAC adsorption preferentially removed more DOC than DON by 10% on average. The results provided herein hence shed light on approaches for reducing organic nitrogen content in treated wastewater.

Associations between testicular hormones at adolescence and attendance at chlorinated swimming pools during childhood

The goal was to evaluate the associations between testicular hormones at adolescence and the exposure to chlorination by-products when attending chlorinated swimming pools. We obtained serum samples from 361 school male adolescents (aged 14–18 years) who had visited swimming pools disinfected with chlorine or by copper–silver ionization. We analysed serum concentrations of inhibin B (two different assays), total and free testosterone, sex hormone-binding globulin, luteinizing hormone (LH), follicle stimulating hormone (FSH) and dehydroepiandrosterone sulphate (DHEAS). There were strong inverse associations between serum levels of inhibin B (both assays) or of total testosterone, adjusted or unadjusted for gonadotropins and the time adolescents had spent in indoor chlorinated pools, especially during their childhood. Adolescents having attended indoor chlorinated pools for more than 250 h before the age of 10 years or for more than 125 h before the age of 7 years were about three times more likely to have an abnormally low serum inhibin B and/or total testosterone (<10th percentile) than their peers who never visited this type of pool during their childhood (odds ratio, 95% CI, 2.83, 1.06–7.52, p = 0.04 and 3.67, 1.45–9.34, p = 0.006, respectively). Such associations were not seen with free testosterone, LH, FSH and DHEAS or with the attendance of outdoor chlorinated pools or of the copper–silver pool. Swimming in indoor chlorinated pools during childhood is strongly associated with lower levels of serum inhibin B and total testosterone. The absorption of reprotoxic chlorination by-products across the highly permeable scrotum might explain these associations.

Reduction of chlorination byproducts in surface water using ceramic nanofiltration membranes

In this study, two ceramic nanofiltration membranes with a molecular weight cutoff of 450 Da (NF450) and 1000 Da (NF1000) were used to reduce the concentration of organic matter (OM) in natural water, and the effect on the formation of disinfection by-products (DBPs) was evaluated. The effects of pressure, conductivity and pH were studied. The formation of trihalomethanes, haloacetic acids, haloacetonitriles and haloketones was evaluated. The results of the study indicated that the permeation flow rate of NF1000 was greater than that of NF450. An increase in the operating pressure improved the efficiency of OM removal and reduced the formation of DPBs. Over 75% of the formation potential of trihalomethanes was eliminated using NF450 membrane. The NF1000 membrane produces smaller decreases in trihalomethanes. As the conductivity increased from 900 μS/cm to 4000 μS/cm, the reduction of trihalomethanes decreased from 51% to 22% and from 80% to 39% for NF1000 and NF450 respectively. The flow through NF450 and NF1000 decreased when the pH of the solution decreased from pH 8.3 to pH 4.5. The values of trihalomethanes rejections at pH 8.3 were 79% and 58% for NF450 and NF1000 respectively, and these values decreased to 65% and 40% at pH 4.5.

Fluorescent Sensing of Chlorophenols in Water Using an Azo Dye Modified β-Cyclodextrin Polymer

A water soluble azo dye modified β-cyclodextrin polymer 4 was synthesized and used as a chemosensor for the detection of chlorinated phenols, model chlorinated by-products (CBPs) of water treatment for drinking purposes. The characterization of the intermediates and the azo dye modified β-CD polymer was done by UV/Vis Spectrophotometry, FT-IR and 1H-NMR spectroscopies. The chlorophenols were capable of quenching the fluorescence of the polymer. The polymer showed greater sensitivity towards 2,4-dichlorophenol, with a sensitivity factor of 0.35 compared to 0.05 and 0.12 for phenol and 4-chlorophenol, respectively. The stability constants (Ks) of the pollutants were also determined by the Benesi-Hildebrand method to be 2.104 × 103 M−1 for 2,4-dichlorophenol and 1.120 × 102 M−1 for 4-chlorophenol.

Carcinogenicity of chemicals in industrial and consumer products, food contaminants and flavourings, and water chlorination byproducts

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Chlorination of chlortoluron: Kinetics, pathways and chloroform formation

Chlortoluron chlorination is studied in the pH range of 3–10 at 25 ± 1 °C. The chlorination kinetics can be well described by a second-order kinetics model, first-order in chlorine and first-order in chlortoluron. The apparent rate constants were determined and found to be minimum at pH 6, maximum at pH 3 and medium at alkaline conditions. The rate constant of each predominant elementary reactions (i.e., the acid-catalyzed reaction of chlortoluron with HOCl, the reaction of chlortoluron with HOCl and the reaction of chlortoluron with OCl −) was calculated as 3.12 (± 0.10) × 10 7 M −2 h −1, 3.11 (±0.39) × 10 2 M −1 h −1 and 3.06 (±0.47) × 10 3 M −1 h −1, respectively. The main chlortoluron chlorination by-products were identified by gas chromatography–mass spectrometry (GC–MS) with purge-and-trap pretreatment, ultra-performance liquid chromatography–electrospray ionization-MS and GC-electron capture detector. Six volatile disinfection by-products were identified including chloroform (CF), dichloroacetonitrile, 1,1-dichloropropanone, 1,1,1-trichloropropanone, dichloronitromethane and trichloronitromethane. Degradation pathways of chlortoluron chlorination were then proposed. High concentrations of CF were generated during chlortoluron chlorination, with maximum CF yield at circumneutral pH range in solution.

Differential global profiling as a new analytical strategy for revealing micropollutant treatment by-products: Application to ethinylestradiol and chlorination water treatment

The detection and structural elucidation of micropollutants treatment by-products are major issues to estimate efficiencies of the processes employed for drinking water production versus endocrine disruptive compounds contamination. This issue was mainly investigated at the laboratory scale and in high concentration conditions. However, potential by-products generated after chlorination can be influenced by the dilution factor employed in real conditions. The present study proposes a new methodology borrowed to the metabolomic science, using liquid chromatography coupled to high-resolution mass spectrometry, in order to reveal potential chlorination by-products of ethinylestradiol in spiked real water samples at the part-per-billion level (5 μg L −1). Conventional targeted measurements first demonstrated that chlorination with sodium hypochlorite (0.8 mg L −1) led to removals of ethinylestradiol over 97%. Then, the developed differential global profiling approach permitted to reveal eight chlorination by-products of EE2, six of them being described for the first time. Among these eight halogenated compounds, five have been structurally identified, demonstrating the potential capabilities of this new methodology applied to environmental samples.

Measurement Technology of Dry Etching Chlorinated Byproducts and Improvement Strategy in Thin Film Transistor Liquid Crystal Display Production

PP-29-018 Background/Aims: The advanced TFT-LCD processes, dry etching of thin film layers is increasingly preferred instead of conventional wet etching processes for new process. The previous studies are focus on greenhouse gases removal efficiency by scrubber, and indicate potential fluorinated or chlorinated compounds of the material being etched. The environment, safety, and health difficult challenges are lack of information on how the chemicals and materials are used and what process byproducts are formed, additional needs are characterizing and controlling plasma etches gas emissions and byproducts. Methods: The thermal processing unit consists of an oxide combustion chamber, a wet scrubber, a vacuum pump, and temperature/pressure control system, integrated in an enclosed unit. Determination of dry etching gas and byproducts using an online extractive Fourier transform infrared spectroscopy and canister sampling/gas chromatography-mass spectrometry method. A portable photo ionization detector used to detect total volatile organic compounds after scrubber. We found sulfur hexafluoride etching gas and 3 byproducts, including sulfur dioxide, ethylene, and hydrogen chloride by FTIR. There were 14 unknown and 6 byproducts before TPU, and 13 byproducts after TPU by Gas Chromatograph-Mass Spectrometer. Results: We found that the scrubber has high destruction removal efficiency for dry etching unknown byproducts at 1000°C. The temperature of partial combustion reactor processing equipment less than 750°C, toxic chlorinated byproducts would be generated after TPU. In this study, we found 34 chlorinated byproducts at abnormal local scrubber. The portable photoionization detector screen method is able to find abnormal scrubber, the concentration of total volatile organic compounds more than normal scrubber after TPU. Conclusion: We have established the dry etching chlorinated byproducts measurement technology and improvement strategy for local scrubber. When the local scrubber was not well maintained, toxic chlorinated byproducts would be generated. The screen method is able to screen out and modify the abnormal local scrubber for improvement.

Risk of Stillbirth in Relation to Disinfection By-products in Taiwan

S-29C6-3 Background/Aims: Recent findings suggest that exposure to disinfection by-products may increase the risk of stillbirth. The results of these studies are inconsistent, but warrant further attention. Methods: To assess the effect of water chlorination by-products on stillbirth, we conducted a population-based case-control study of 3289 cases of stillbirth and a random sample of 32,890 control subjects from 396,049 Taiwanese newborns in 2001–2003 using information from the Birth Registry and Waterworks Registry in Taiwan. We compared the risk of stillbirth in 4 disinfection by-product exposure categories based on the levels of total trihalomethanes (TTHMs) representing high (TTHMs 20+ μg/L), medium (TTHMs 10–19 μg/L), low exposures (TTHMs 5–9 μg/L), and 0–4 μg/L as the reference category. Results: In logistic regression analysis adjusting for gender, maternal age, plurality, conception of season, and population density of the municipality where the mother lived during pregnancy, the odds ratio for stillbirth was 1.10 (95% CI: 1.00–1.21) for medium exposure and 1.06 (95% CI: 0.96–1.17) for high exposure compared to reference category. Conclusion: The risk of stillbirth may associate with women exposure to disinfection by-products in Taiwanese drinking water.