Levels Of Disinfection By-products Research Articles

Characterization, DBPs formation, and mutagenicity of soluble microbial products (SMPs) in wastewater under simulated stressful conditions

Soluble microbial products (SMPs) are an important group of components in activated sludge-treated wastewater effluents. Chlorination is the most widely used method for disinfecting wastewater effluents. During chlorination of wastewater effluents, SMPs may act as precursors to form disinfection by-products (DBPs), which may pose adverse impacts on the organisms in the receiving water body. In this study, SMPs were prepared by simulating activated sludge under different stressful conditions, including high ammonia content (HA), high salinity (HS), high levels of heavy metals (HM) and high temperature (HT), as well as a normal state (NS). The molecular weight (MW) distribution of SMPs was characterized using gel permeation chromatography (GPC). Chlorination of SMPs was conducted with sodium hypochlorite. Several species of DBPs were detected using gas chromatography–mass spectrometry (GC–MS). The mutagenicity of SMPs solutions and SMPs solutions treated with chlorination was also evaluated using the umu test. Compared with NS, stressful conditions were induced to produce more low MW components of SMPs. Stressful conditions, had no significant effect on the species of DBPs, but played a crucial role in the levels of DBPs produced in SMPs solutions during chlorination. Among the stressful conditions tested, HT and HS resulted in higher levels of both carbon-containing DBPs (C-DBPs) and nitrogen-containing DBPs (N-DBPs). Levels of C-DBPs and N-DBPs were lower under HM condition. HA stimulated the production of N-DBPs, but had no impact on the levels of C-DBPs. The mutagenicity of SMPs solutions was higher under the stressful conditions than that under NS condition in both before and after chlorination. For each SMPs solution, the mutagenicity of SMPs increased after the chlorination, except for SMPs solution under HM and NS conditions.

Short-term spatial and temporal variability of disinfection by-product occurrence in small drinking water systems

Disinfection by-products (DBPs) constitute a large family of compounds. Trihalomethanes and haloacetic acids are regulated in various countries, but most DBPs are not. Monitoring DBPs can be delicate, especially for small systems, because various factors influence their formation and speciation. Short-term variations of DBPs can be important and particularly difficult for small systems to handle because they require robust treatment and operation processes. According to our knowledge, for the first time, our study covers the short-term variability of regulated and non-regulated DBP occurrence in small systems in the summer. An intensive sampling program was carried out in six small systems in Canada. Systems in the provinces of Newfoundland and Labrador and Quebec were sampled daily at the water treatment plant and at six different locations along the distribution system. Five DBP families were studied: trihalomethanes, haloacetic acids, haloacetonitriles, halonitromethanes and haloketones. Results show that there were considerable variations in DBP levels from week to week during the month of study and even from day to day within the week. On a daily basis, DBP levels can fluctuate by 22% to 96%. Likewise, the large number of sampling locations served to observe DBP variations along the distribution system. Observations revealed some degradation and decomposition of non-regulated DBPs never before studied in small systems that are associated with the difficulty these systems experience in maintaining adequate levels of residual disinfectant. Finally, this study reveals that the short term temporal variability of DBPs is also influenced by spatial location along the distribution system. In the short term, DBP levels can fluctuate by 23% at the beginning of the system, compared to 40% at the end. Thus, spatial and temporal variations of DBPs in the short term may make it difficult to select representative locations and periods for DBP monitoring purposes in small systems.

ACTIVE MAP OF READY-TO-EAT LETTUCE: INTERPLAY BETWEEN FOOD QUALITY AND SAFETY (THE QUAFETY APPROACH)

Oxidative enzymatic browning of cut edges and microbial spoilage are the two major causes of deterioration of ready-to-eat lettuce. Furthermore, we have demonstrated that these two processes are interrelated and the presence of spoilage pseudomonad bacteria on cut lettuce surface hastens the accumulation of phenolics and enhances browning, presumably as part of the host defense response. Preventing browning by heat treatment promoted bacterial growth and tissue maceration of Pectobacterium-inoculated lettuce core discs. The red-colored phenolic oxidation products have been isolated from cut lettuce and are currently under investigation. Modified atmosphere packaging (MAP) is used to preserve the quality of fresh-cut lettuce by inhibiting both the oxidative browning and the growth of microbial populations. Flushing the packages with a gas mix of desired composition (active MAP) expedites the achievement of favorable atmosphere conditions improving the product quality preservation. At the same time, the active MAP favored the survival of Salmonella on lettuce leaves, possibly due to the elimination of its natural antagonists. Atmosphere modification does not ensure microbiological safety of ready-to-eat lettuce and must be supported by appropriate sanitation practices. Washing with active chlorine followed by potable water rinsing did not taint shredded lettuce with unacceptable level of disinfection byproducts but produced wastewater heavily contaminated with trihalomethanes. The comprehensive approach to quality and safety of ready to eat fresh products is the basis of the EU FP7 QUAFETY project.

Disparity in disinfection byproducts concentration between hot and cold tap water

The quality of water entering a distribution system may differ substantially from the quality at the point of exposure to the consumer. This study investigated temporal variations in the levels of regulated and non-regulated disinfection byproducts (DBPs) in cold and hot tap water in a home on a medium-sized municipal water system. In addition, samples were collected directly from the water plant with some being held in accordance with a simulated distribution system (SDS) test protocol. The location for this work was a system in western Massachusetts, USA that uses free chlorine as a final disinfectant. Very little short term variability of DBPs at the point of entry (POE) was observed. The concentration of DBPs in the time-variable SDS test was similar to concentrations in the cold water tap. For most DBPs, the concentrations continued to increase as the cold water tap sample was held for the time-variable SDS incubation period. However, the impact of heating on DBP levels was compound specific. For example, the concentrations of trihalomethanes (THMs), dichloroacetic acid (DCAA) and chloropicrin (CP) were substantially higher in the hot water tap than in the cold water time-variable SDS samples. In contrast, the concentration of trichloroacetic acid (TCAA) was lower in the heated hot tap water, but about equal to that observed in the cold tap water. The situation was more pronounced for dichloroacetonitrile (DCAN), bromodichloroacetic acid (BDCAA), bromochloroacetic acid (BCAA) and 1,1,1-trichloropropanone (TCP), which all showed lower concentrations in the hot water then in either of the cold water samples (instantaneous or time-variable SDS). The latter was viewed as a clear indication of thermally-induced decomposition. The ratio of unknown total organic halide (UTOX) to TOX was substantially lower in the hot tap water as the THM to TOX ratio became correspondingly larger. The results of this study show that DBP exposure in the home is not well represented by concentrations measured in cold water taps where most compliance monitoring is done.

Ingestion of Nitrate and Nitrite from Drinking Water and Diet: a Prospective Analysis of Epithelial Ovarian Cancer Risk among Postmenopausal Women in Iowa

Ingestion of Nitrate and Nitrite from Drinking Water and Diet: a Prospective Analysis of Epithelial Ovarian Cancer Risk among Postmenopausal Women in IowaAbstract Number:1930 Maki Inoue-Choi*, Rena Jones, Kristin Anderson, Kenneth Cantor, James Cerhan, Stuart Krasner, Kim Robien, Peter Weyer, and Mary Ward Maki Inoue-Choi* National Cancer Institute, United States, E-mail Address: [email protected] Search for more papers by this author , Rena Jones National Cancer Institute, United States, E-mail Address: [email protected] Search for more papers by this author , Kristin Anderson University of Minnesota, United States, E-mail Address: [email protected] Search for more papers by this author , Kenneth Cantor National Cancer Institute, United States, E-mail Address: [email protected] Search for more papers by this author , James Cerhan Mayo Clinic, United States, E-mail Address: [email protected] Search for more papers by this author , Stuart Krasner Metropolitan Water District og Sourthern California, United States, E-mail Address: [email protected] Search for more papers by this author , Kim Robien George Washington University, United States, E-mail Address: [email protected] Search for more papers by this author , Peter Weyer University of Iowa, United States, E-mail Address: [email protected] Search for more papers by this author , and Mary Ward National Cancer Institute, United States, E-mail Address: [email protected] Search for more papers by this author AbstractBackground: Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds (NOC), potential human carcinogens. Nitrogen from agricultural fertilizers and other sources can contaminate drinking water supplies. Objective: To evaluate the association of nitrate/nitrite ingestion and ovarian cancer risk.Methods: Dietary nitrate and nitrite intakes were assessed using a food frequency questionnaire among 28,555 cancer-free postmenopausal women enrolled in the Iowa Women’s Health Study in 1986. Historical data on drinking water source was obtained from the 1989 survey. Nitrate-nitrogen (NO3-N) and disinfection byproduct (DBP) levels were estimated for Iowa public water utilities; average levels were computed for the women’s duration of use of each public supply. Multivariable-adjusted hazard ratios (HR) and 95% confidence intervals (CI) were calculated using Cox proportional hazards regression. We tested interactions of nitrate with DBPs and selected dietary intakes known to influence NOC formation.Results: Through 2010, 315 incident invasive ovarian cancers were identified. Ovarian cancer risk was 2.2 times higher (95%CI=1.3-3.6) among women in the highest quartile (=2.98 mg/L) compared to the lowest quartile of NO3-N (=0.47 mg/L) in public water, regardless of DBP levels (ptrend=0.001). Risk among private well users was elevated (HR=1.5, CI=0.9-2.5). Associations were stronger when vitamin C intake was <median, especially for private well use (pinteraction=0.01). Dietary nitrate intake was associated with lower ovarian cancer risk (HRQ5 vs. Q1=0.6, CI=0.4-0.9, ptrend=0.01). Ovarian cancer risk increased by 11% with each 0.1 mg/d increment in nitrite intake from processed meats (CI=1.0-1.2).Conclusions: Higher nitrate exposures from public water supplies and private well use were associated with increased ovarian cancer risk, especially with low vitamin C intake. Higher nitrite intake from processed meats may increase ovarian cancer risk.

Seasonal Variation of Urinary Trichloroacetic Acid (TCAA) Concentrations Measured on Multiple Consecutive Days in a Prospective, Pre-Conception Cohort

Seasonal Variation of Urinary Trichloroacetic Acid (TCAA) Concentrations Measured on Multiple Consecutive Days in a Prospective, Pre-Conception CohortAbstract Number:1826 Kyley Cox*, Christina Porucznik, James VanDerslice, Joseph Stanford, Diana Wilkins, Eric Brozek, David Anderson, and Nicole Bailey Kyley Cox* University of Utah Department of Family and Preventive Medicine, United States, E-mail Address: [email protected] Search for more papers by this author , Christina Porucznik University of Utah Department of Family and Preventive Medicine, United States, E-mail Address: [email protected] Search for more papers by this author , James VanDerslice University of Utah Department of Family and Preventive Medicine, United States, E-mail Address: [email protected] Search for more papers by this author , Joseph Stanford University of Utah Department of Family and Preventive Medicine, United States, E-mail Address: [email protected] Search for more papers by this author , Diana Wilkins University of Utah Center for Human Toxicology, United States, E-mail Address: [email protected] Search for more papers by this author , Eric Brozek University of Utah Center for Human Toxicology, United States, E-mail Address: [email protected] Search for more papers by this author , David Anderson University of Utah Center for Human Toxicology, United States, E-mail Address: [email protected] Search for more papers by this author , and Nicole Bailey University of Utah Department of Family and Preventive Medicine, United States, E-mail Address: [email protected] Search for more papers by this author AbstractBackground: Control of bacterial contamination of drinking water by disinfectants leads to the production of disinfection-by-products (DBPs). TCAA is the second most prevalent haloacetic acid in chlorinated water. Urinary TCAA is a validated biomarker of TCAA exposure by ingestion of chlorinated drinking water. Objective: Evaluate variation of urinary TCAA concentrations by season.Methods: A prospective, pre-conception cohort of couples (women 18–35, men 18–40) was recruited in Utah beginning in early 2012. Recruitment is ongoing. Women observed cervical mucus to identify the fertile window. Participants collected first-morning urine samples beginning at the onset of the fertile window, after which men discontinued collecting but women collected for the remainder of the cycle. TCAA was measured in each urine sample using quantitative GC-MS. Geometric means (GM) with 95% confidence intervals (CI) were calculated for each season using STATA ver. 12. Seasons were defined as follows: spring (Mar – May); summer (June – Aug); fall (Sept – Nov); winter (Dec – Feb).Results: The GM for all specimens (n=1521) was 2.42 ng/mL (95% CI 2.32, 2.53). The highest concentrations were observed in specimens collected during spring months (n=212, GM 3.04 ng/mL, 95% CI 2.76, 3.35), followed by fall (n=428, GM 2.69 ng/mL, 95% CI 2.47, 2.93), and summer (n=519, GM 2.53 ng/mL, 95% CI 2.37, 2.69). These levels were significantly higher than the levels observed during winter (n=362, GM 1.76 ng/mL, 95% CI, 1.61, 1.93). Men had slightly higher levels than women (GM 2.64 vs. 2.36 ng/mL) but the difference was not statistically significant.Conclusions: These preliminary findings suggest that TCAA exposures vary seasonally in a pattern similar to the levels of disinfection byproducts in tap water.

Trihalomethanes in marine mammal aquaria: Occurrences, sources, and health risks

Disinfecting water containing the high levels of dissolved organic carbon (DOC) commonly generated during pinniped husbandry may cause the formation of carcinogenic disinfection byproducts (DBPs). Little information is available on DBP levels, sources, and health risks in marine mammal aquaria. Using the commonly observed trihalomethanes (THMs) as a DBP indicator, we monitored concentrations for seven months at The Marine Mammal Center in Sausalito, California, one of the largest pinniped rehabilitation facilities in the world. Concentrations of THMs ranged 1.1–144.2 μg/L in pool waters and generally increased with number of animals housed (P < 0.05). To identify the sources of THM precursors in marine mammal aquaria, we intensively monitored the mass flows of potential THM precursors (i.e. food and wastes) in an isolated system with nine individual California sea lions to evaluate the sources and reactivity of dissolved organic carbon (DOC) for 2–5 weeks. The common frozen foods used in feeding pinnipeds, including herring, sardine, and squid, produced an average of 22–34 mg-DOC/g-food in water and 836–1066 μg-THM/g-food after chlorination, whereas the fecal materials, including fresh scat, decomposed scat, and urine, produced 2–16 mg-DOC/g-waste and 116–768 μg-THM/g-waste. Food not eaten by animals could cause a sharp increase of DOC and DBP production and therefore should be removed rapidly from pools. Marine mammal husbandry staff and trainers are at risk (5.16 × 10−4 to 1.30 × 10−3) through exposure of THMs, exceeding the negligible risk level (10−6) defined by the US Environmental Protection Agency.

Disinfection by-product occurrence in selected European waters

In this paper we report the findings of a European survey of regulated and emerging disinfection by-products (DBPs) in drinking waters in selected regions that were part of epidemiology studies. The levels of DBPs found reflected the diverse regions from which the samples were collected, the different treatment/disinfection processes and the different source waters. In addition to a wide range of concentrations of DBPs (e.g. median trihalomethanes (THMs) of 8–85 μg L –1 ), bromine incorporation was quite diverse (e.g. some waters were highly dominated by bromine-containing DBPs, whereas others only had chlorine-containing species). Bromine incorporation was highest in the haloacetonitriles (HANs) and was lowest in the trihalogenated haloacetic acids (THAAs). In addition, the ratios of THMs to HAAs, THMs to HANs, and THAAs to dihalogenated HAAs varied. Exposure assessment based on THMs alone was not sufficient for indicating the presence of emerging DBPs of health concern. Occurrence studies must include a more diverse group of analytes to better understand exposure to DBPs of health concern.

정수처리 공정에서 모델 물질들을 이용한 천연유기물질 처리능 및 소독부산물 생성능 평가

While a range of natural organic matter (NOM) types can generate high levels of disinfection by-products (DBPs) after chlorination, there is little understanding of which specific compounds act as precursors. Use of eight model compounds allows linking of explicit properties to treatability and DBP formation potential (DBPFP). The removal of model compounds by various treatment processes and their haloacetic acid formation potential (HAAFP) before and after treatment were recorded. The model compounds comprised a range of hydrophobic (HPO) and hydrophilic (HPI) neutral and anionic compounds. On the treatment processes, an ozone oxidation process was moderate for control of model compounds, while the HPO-neutral compound was most treatable with activated carbon process. Biodegradation was successful in removing amino acids, while coagulation and ion exchange process had little effect on neutral molecules. Although compared with the HPO compounds the HPI compounds had low HAAFP the ozone oxidation and biodegradation were capable of increasing their HAAFP. In situations where neutral or HPI molecules have high DBPFP additional treatments may be required to remove recalcitrant NOM and control DBPs.

Health Risk Evaluation of Disinfection By-Products (DBPs) for Indoor Swimming Pool Users via Life Cycle Impact Assessment Approach

Due to continuous disinfection and constant organic load from swimmers, indoor swimming pools constitute environments with high levels of DBPs in water and air, some of which are linked to human health concerns. The purpose of this study is to customize current global-scale or continental scale life cycle human health impact assessment models to indoor swimming pool applications and subsequently use the model to compare different operation scenarios, which can provide relatively straight forward ideas for possible mitigation strategies. A comparison study is carried out between “baseline” scenario and four specific ‘what-if’ scenarios (using alternative disinfectant, reducing precursors, increasing ventilation, and changing characteristics of the air-water surface). We build the indoor-scale model based on USEtox, the consensus environmental model for characterisation of human and ecotoxicological impacts in Life Cycle Impact Assessment (LCIA). The model estimates the potential health risks for adults and children for 20 years during which age-specific intake factors change over time. The primary results indicated the impact from inhalation dominates the overall human health impact, while the dermal adsorption during swimming also makes significant contribution. The chloroform and trichloramine are identified as major stressors for inhalation human impact, while chloroform for dermal absorption impact. Through the scenario comparison, improving the ventilation of indoor swimming pools is an effect way to reduce the human health impact for all subjects. Another promising method is to control the precursors through increasing freshwater exchange, especially for the heavily-used pools. This study implies the choice of mitigation strategies should depend on the function and operation time of the pool. Through incorporating the proposed life cycle human health impact assessment model to the cradle-to-grave life cycle assessment studies, a systematic and comprehensive environmental profile of indoor swimming usage can be available.

Monitoring of some disinfection by-products in drinking water treatment plants of El-Beheira Governorate, Egypt

Two water treatment plants (Edfina and Kom-Hamada) in El-Beheira Governorate were selected to monitor disinfection by-products (DBPs) concentrations. A 12-month monitoring program from October 2011 to September 2012 was established for measuring some DBPs and some water quality parameters such as temperature, pH, turbidity, total organic carbon (TOC), ammonia and bromide. The concentrations of DBPs were determined by gas chromatography with ECD (GC-ECD). Trihalomethanes (THMs) and chloral hydrate (CH) were commonly seen in all samples collected from Plant 1 (Edfina) and Plant 2 (Kom-Hamada). THMs mean concentrations ranged from 34.5 to 64.6 μg/L and from 28.2 to 52.8 μg/L for Plant 1 and Plant 2. CH mean concentrations ranged from 3.3 to 6.76 μg/L and from 2.8 to 3.9 μg/L for Plant 1 and Plant 2, respectively. Dichloroacetonitrile (DCAN) mean concentrations ranged from 1.1 to 2.0 μg/L and from 1.2 to 2.1 μg/L for Plant 1 and Plant 2, respectively. Chloropicrin (CP) was detected in Plant 1 only with mean concentration ranging from 0.91 to 1.1 μg/L. Trichloroacetonitrile (TCAN) and dibromoacetonitrile (DBAN) were below the limit of quantification (LOQ) in all samples. Higher concentrations of THMs were measured in summer and spring as compared to winter. DBPs concentrations were higher in Plant 1 than in Plant 2. The DBPs levels in all samples collected from Edfina and Kom-Hamada were generally below the guideline values set by the Egyptian Health Minister in 2007.

Bioanalytical and chemical assessment of the disinfection by-product formation potential: Role of organic matter

Disinfection by-products (DBP) formed from natural organic matter and disinfectants like chlorine and chloramine may cause adverse health effects. Here, we evaluate how the quantity and quality of natural organic matter and other precursors influence the formation of DBPs during chlorination and chloramination using a comprehensive approach including chemical analysis of regulated and emerging DBPs, total organic halogen quantification, organic matter characterisation and bioanalytical tools. In vitro bioassays allow us to assess the hazard potential of DBPs early in the chain of cellular events, when the DBPs react with their molecular target(s) and activate stress response and defence mechanisms. Given the reactive properties of known DBPs, a suite of bioassays targeting reactive modes of toxic action including genotoxicity and sensitive early warning endpoints such as protein damage and oxidative stress were evaluated in addition to cytotoxicity. Coagulated surface water was collected from three different drinking water treatment plants, along with reverse osmosis permeate from a desalination plant, and DBP formation potential was assessed after chlorination and chloramination. While effects were low or below the limit of detection before disinfection, the observed effects and DBP levels increased after disinfection and were generally higher after chlorination than after chloramination, indicating that chlorination forms higher concentrations of DBPs or more potent DBPs in the studied waters. Bacterial cytotoxicity, assessed using the bioluminescence inhibition assay, and induction of the oxidative stress response were the most sensitive endpoints, followed by genotoxicity. Source waters with higher dissolved organic carbon levels induced increased DBP formation and caused greater effects in the endpoints related to DNA damage repair, glutathione conjugation/protein damage and the Nrf2 oxidative stress response pathway after disinfection. Fractionation studies indicated that all molecular weight fractions of organic carbon contributed to the DBP formation potential, with the humic rich fractions forming the greatest amount of DBPs, while the low molecular weight fractions formed more brominated DBPs due to the high bromide to organic carbon ratio. The presence of higher bromide concentrations also led to a higher fraction of brominated DBPs as well as proportionally higher effects. This study demonstrates how a suite of analytical and bioanalytical tools can be used to effectively characterise the precursors and formation potential of DBPs.

Abstract 149: Dietary intake of nitrate and nitrite, nitrate in drinking water, and ovarian cancer risk among postmenopausal women in Iowa.

Abstract Background: Nitrate and nitrite are precursors of N-nitroso compounds, known animal and human carcinogens. Nitrate and nitrite are common in foods, such as vegetables and processed meats, and nitrate is a contaminant of drinking water. We previously reported an increased ovarian cancer risk associated with higher nitrate intake in public water supplies in the Iowa Women's Health Study. Here, we report results based on an additional 12 years of follow-up and we present results for dietary nitrate and nitrite intake. Methods: Among 28,555 postmenopausal women aged 55–69 y at baseline, we identified 315 incident epithelial ovarian cancers between 1986 and 2010. Dietary nitrate and nitrite intakes were assessed using a food frequency questionnaire at baseline. Information on drinking water source was obtained in 1989. Nitrate-nitrogen (NO3-N) levels in public water supplies (average level 1955-1988) and water sources (finished surface or ground water) were from a database of monitoring data for Iowa water utilities. Cox proportional hazards regression generated hazard ratios (HR) and 95% confidence intervals (CI). Because disinfection by-products (DBP) are higher in surface water and have been associated with increased risk for certain cancers, we determined whether the association between nitrate intake from drinking water and ovarian cancer risk differed by water source. Results: Neither total dietary nitrate nor nitrite intake was associated with ovarian cancer risk after adjusting for age, energy intake, family history of ovarian cancer, number of live births, and history of unilateral oophorectomy. Nitrate and nitrite intakes from animal or plant sources, or processed meats were not associated with ovarian cancer risk. Among women who drank public water, we observed an increased risk for ovarian cancer with higher average levels of NO3-N (ptrend=0.004). Compared with women in the lowest quartile of NO3-N levels (&amp;lt;0.36 mg/L), risk was 1.81 (95% CI=1.08-3.05) and 2.02 (95% CI=1.21-3.36) times higher in the third (1.0-2.5 mg/L) and fourth (&amp;gt;2.5 mg/L) quartiles, respectively. Ovarian cancer risk among private well water drinkers was elevated (HR=1.52, 95% CI=0.91-2.53) but not statistically significantly different from the referent group. When stratified by water source, the positive association between NO3-N levels in public water and ovarian cancer risk was confined to women who drank water from surface sources (ptrend=0.007; pinteraction=0.04). Conclusions: Dietary nitrate or nitrite intake was not associated with ovarian cancer risk. Our findings for nitrate intake from public water supplies suggest that nitrate intake from drinking water may increase ovarian cancer risk, particularly in the likely presence of other contaminants found in surface water. Further evaluation of DBP and other water contaminant levels on ovarian cancer risk in this population is warranted. Citation Format: Maki Inoue-Choi, Kristin E. Anderson, James R. Cerhan, Peter J. Weyer, Mary H. Ward. Dietary intake of nitrate and nitrite, nitrate in drinking water, and ovarian cancer risk among postmenopausal women in Iowa. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 149. doi:10.1158/1538-7445.AM2013-149

Variability of chlorination by-product occurrence in water of indoor and outdoor swimming pools

Swimming is one of the most popular aquatic activities. Just like natural water, public pool water may contain microbiological and chemical contaminants. The purpose of this study was to study the presence of chemical contaminants in swimming pools, in particular the presence of disinfection by-products (DBPs) such as trihalomethanes (THMs), haloacetic acids (HAAs) and inorganic chloramines (CAMi). Fifty-four outdoor and indoor swimming pools were investigated over a period of one year (monthly or bi-weekly sampling, according to the type of pool) for the occurrence of DBPs. The results showed that DBP levels in swimming pools were greater than DBP levels found in drinking water, especially for HAAs. Measured concentrations of THMs (97.9 vs 63.7 μg/L in average) and HAAs (807.6 vs 412.9 μg/L in average) were higher in outdoor pools, whereas measured concentrations of CAMi (0.1 vs 0.8 mg/L in average) were higher in indoor pools. Moreover, outdoor pools with heated water contained more DBPs than unheated pools. Finally, there was significant variability in tTHM, HAA9 and CAMi levels in pools supplied by the same municipal drinking water network, suggesting that individual pool characteristics (number of swimmers) and management strategies play a major role in DBP formation.

Bioanalytical Assessment of the Formation of Disinfection Byproducts in a Drinking Water Treatment Plant

Disinfection of drinking water is the most successful measure to reduce water-borne diseases and protect health. However, disinfection byproducts (DBPs) formed from the reaction of disinfectants such as chlorine and monochloramine with organic matter may cause bladder cancer and other adverse health effects. In this study the formation of DBPs through a full-scale water treatment plant serving a metropolitan area in Australia was assessed using in vitro bioanalytical tools, as well as through quantification of halogen-specific adsorbable organic halogens (AOXs), characterization of organic matter, and analytical quantification of selected regulated and emerging DBPs. The water treatment train consisted of coagulation, sand filtration, chlorination, addition of lime and fluoride, storage, and chloramination. Nonspecific toxicity peaked midway through the treatment train after the chlorination and storage steps. The dissolved organic matter concentration decreased after the coagulation step and then essentially remained constant during the treatment train. Concentrations of AOXs increased upon initial chlorination and continued to increase through the plant, probably due to increased chlorine contact time. Most of the quantified DBPs followed a trend similar to that of AOXs, with maximum concentrations observed in the final treated water after chloramination. The mostly chlorinated and brominated DBPs formed during treatment also caused reactive toxicity to increase after chlorination. Both genotoxicity with and without metabolic activation and the induction of the oxidative stress response pathway showed the same pattern as the nonspecific toxicity, with a maximum activity midway through the treatment train. Although measured effects cannot be directly translated to adverse health outcomes, this study demonstrates the applicability of bioanalytical tools to investigate DBP formation in a drinking water treatment plant, despite bioassays and sample preparation not yet being optimized for volatile DBPs. As such, the bioassays are useful as monitoring tools as they provide sensitive responses even at low DBP levels.

Minimization of the formation of disinfection by-products

The drinking water industry is required to minimize DBPs levels while ensuring adequate disinfection. In this study, efficient and appropriate treatment scheme for the reduction of disinfection by-product (DBPs) formation in drinking water containing natural organic matter has been established. This was carried out by the investigation of different treatment schemes consisting of enhanced coagulation, sedimentation, disinfection by using chlorine dioxide/ozone, filtration by sand filter, or granular activated carbon (GAC). Bench scale treatment schemes were applied on actual samples from different selected sites to identify the best conditions for the treatment of water. Samples were collected from effluent of each step in the treatment train in order to analyze pH, UV absorbance at 254nm (UVA254), specific UV absorbance at 254nm (SUVA254), dissolved organic carbon (DOC), haloacetic acids (HAAs) and trihalomethanes (THMs). The obtained results indicated that using pre-ozonation/enhanced coagulation/activated carbon filtration treatment train appears to be the most effective method for reducing DBPs precursors in drinking water treatment.

Fractionated algal organic materials as precursors of disinfection by-products and mutagens upon chlorination

Cells and proteins of Chlamydomonas sp. (a common green alga in local reservoirs) were separated by ultrafiltration respectively into 3 fractions with variable molecular weights (MW: >100, 10–3 and <3kDa). After chlorination (20°C, pH 7, Cl2/DOC ratio of 20mgCl2mg−1, 120h), levels of disinfection by-products (DBPs) and mutagenicity (via Salmonella T100 mutation assay, −S9) were analyzed. The highest yields of chloroform (2571μmolmolC−1), DCAA (19,083μmolmolC−1) and TCAA (4939μmolmolC−1) were observed from the fraction of MW>100kDa, while the fraction of 3–10kDa was potent DCAN precursor. In contrast, the chlorinated MW 3–10kDa cell fraction showed high mutagenicity (maximum level of 93revμL−1 at 2min), while the MW>100kDa cell fraction showed low mutagenicity (maximum level of 16.6revμL−1 at 7200min) after chlorination. This indicated that unmeasured DBPs or possible interactions among the DBPs contributed to the mutagenicity. Comparing between the cell and protein fractions, the former was more potent in forming chloroform, DCAA, TCAA, DCAN and TCAN. This is the first study that fractionated algal cells and proteins were examined for DBP formation and mutagenicity.

THE EFFECT OF BOILING AND FILTERING ON THE CONCENTRATION OF DISINFECTION BY-PRODUCTS IN TAP WATER

Background and aims: Disinfection by-products (DBPs) are ubiquitous contaminants in drinking tap water with potential to produce adverse health effects such as bladder cancer and adverse reproductive effects. Filtering and boiling tap water can lead to changes in the disinfection by-products levels and affect the exposure through ingestion. Methods: Changes in the concentration of 4 Trihalomethanes (THM4), MX and bromate were tested when boiling and filtering high bromine-containing tap water from Barcelona. For filtering we used a pitcher-type filter and a household reverse osmosis filter. For boiling we used an electric kettle, a saucepan and a microwave. Samples were taken before and after each treatment to determine the change in the DBPs concentration. pH, conductivity and free and total chlorine were also measured. Trihalomethanes were measured in quadruplicate samples using gas chromatography/electron capture detection. MX was solid phase extracted from water samples, a volatile isopropyl derivative was formed and analysed by gas chromatography - high resolution mass spectrometry. Ion chromatography with suppressed conductivity detection was used for bromate. Results: A high reduction of THM4 (reduction ranging from 97% to 48%) and MX (reduction ranging from 72% to 54%) was observed for all experiments. Bromine-containing trihalomethanes were most eliminated when filtering and chloroform when boiling water. Bromate was highly reduced with reverse osmosis but showed little effect in the other experiments. Conclusions: These findings suggest that exposure to THM4 and MX through ingestion is reduced when using these household appliances while bromate reduction is device-dependent. This should be taken into account in exposure assessment of epidemiological studies.

AN ANALYSIS OF SPATIAL VARIABILITY IN DISINFECTION BY-PRODUCT CONCENTRATIONS FOR EXPOSURE ASSESSMENT APPLICATIONS

Background and Aims: Many epidemiological studies of disinfection by-products (DBPs) in public water systems (PWSs) rely on system average trihalomethane (i.e., THM4; sum of chloroform, dibromochloromethane, bromodichloromethane, and bromoform) and haloacetic acid (i.e., HAA5; sum of monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid) concentrations as surrogates for chemical-specific personal exposures. The study objective is to assess intrasystem variation and evaluate the utility of various methods for determining spatial variability of DBPs. Methods: To determine the utility of system-averages in estimating DBP levels, we assessed spatial variability in THM4 and HAA5 monitoring data for 144 and 132 PWSs in Massachusetts from 1995-2004. High spatial variability was defined using three methods. Methods 1 and 2 consider a PWS to have high spatial variability if the absolute difference between at least two sampling locations is •20 and •30 •g/L, respectively. Method 3 categorizes concentrations based on cut-points of regulatory significance (&lt;40 µg/L, 40-80 µg/L, &gt;80 µg/L), and a PWS is defined as having high spatial variation if same-day sample concentrations fall into multiple categories. Results: For THM4, 108 PWSs (75%) had high spatial variability according to Method 1, compared to 95 PWSs (66%) using Method 2. Results for HAA5 were lower with 79 PWSs (59%) and 60 PWSs (45%) based on Methods 1 and 2, respectively. Over half of these PWSs had high THM4 and HAA5 spatial variability for at least 25% of their sampling dates. Using only chlorinated surface water PWSs from 1996 (17 PWSs), we found comparable results from Methods 1 and 3, with 76% of PWSs having high spatial variation. Conclusions: The spatial variability noted within PWSs could result in misclassification bias if system averages are used to estimate individual-level DBP exposures. Therefore, exposure assessment approaches should target systems with minimal spatial variability for epidemiological application.

Disinfection by-products in drinking water – a case study on Calgary, Alberta, Canada

Disinfection by-products (DBPs) have been monitored in Calgary's drinking water for approximately 15 years. The variability of the DBPs has typically exhibited similar patterns over the period of monitoring. Due to the nature of the surface waters supplying the water treatment plants, the level of DBPs was largely influenced by surface runoff events where the level of natural organic matter (NOM) increased, which was characterized by a relatively high total organic carbon (TOC) content. Principal component analysis (PCA) was utilized for this study to quickly identify the key underlying correlations present within the very large, complex multivariate data matrix. Apart from TOC, chlorine demand, chlorine residual and temperature were observed to correlate with the formation of DBPs in the finished drinking water. In addition to TOC, PCA also indicates that pH and temperature in the distribution system could have an influence on the variability of DBPs in Calgary's drinking water. It was apparent that upgrades to the water treatment systems in Calgary have resulted in an improved removal of DBP precursors such as NOM prior to chlorination, which is a key factor in reducing the DBP levels in the drinking water, thereby providing an enhanced level of public health protection.