Disinfection By-products In Tap Water Research Articles

Impact of boiling on chemical and physical processes for reduction of halomethanes, haloacetonitriles, and haloacetic acids in drinking water

Tap water is boiled by families across the globe in their daily life for cooking food and beverages, as well as for controlling some chlorine-resistant organisms to improve the water quality. However, the effects of boiling methods (heating temperature, heating modes, open or closed containers) on water quality, in particular the reduction of disinfection byproducts (DBPs), are unclear. This comprehensive research demonstrates that during the heating process, trihalomethanes (THMs) were markedly decreased, haloacetonitriles (HANs) were drastically reduced and sometimes completely removed, while haloacetic acids (HAAs) were reduced the least. Heating to boiling in open containers reduced DBPs concentrations more than heating in the closed containers. Residual chlorine from 0.1 to 5.0 mg/L did not affect the removal of HANs, but could increase concentrations of HAAs likely due to reaction of organic matter with chlorine at elevated temperatures. THMs demonstrated good removal at 0.1–1 mg/L residual chlorine, but less removal at 5 mg/L residual chlorine. Sodium chloride (salt), often added as seasoning agent in the process of family cooking, was found to have little effect on the removal of DBPs during cooking and boiling. Compared with the toxicity of DBPs in tap water, boiling could greatly reduce both the cytotoxicity and carcinogenicity through removal of DBPs. Consequently, boiling of tap water had a significant effect on reducing human exposure to DBPs and their associated toxicities.

Occurrence and modeling of disinfection byproducts in distributed water of a megacity in China: Implications for human health

Disinfection byproducts (DBPs) are initially formed in the process of chlorination in the drinking water treatment plants (DWTPs), then further formed in the distribution system due to the presence of residual chlorine and reactive organic matters. However, in China, DBPs are monitored in the effluent from the DWTPs, but less is known about concentrations of DBPs in tap water since they are usually monitored once per half a year. The smart water service system is establishing real-time monitoring of water indices, although DBPs are an urgent need, they are difficult to monitor in real-time due to their diversity and complicated detection methods. If the correlation between DBP concentration and routinely real-time monitored water quality parameters (e.g., pH value, residual chlorine, ammonia) can be evaluated, the concentration of DBPs can be predicted, which will strengthen the control of tap water safety. This article comprehensively assessed the physicochemical parameters and the occurrence of DBP formation in the tap water with an 18-month investigation in Z city (China). DBP formation in tap water of different seasons and different water sources were compared. Based on the relationship between DBPs and physicochemical parameters, linear prediction and nonlinear prediction models of trihalomethanes (THMs), haloacetonitriles (HANs) and haloacetic acids (HAAs) were established, and the accuracy of these models was verified by measured data. Finally, the toxicity and carcinogenic and non-carcinogenic health risk assessment of DBPs in tap water were analyzed.

Human Activity Indicated by Primary, Secondary and Tertiary Industries May Affect the Occurrence of Disinfection By-Products in Tap Water

Human Activity Indicated by Primary, Secondary and Tertiary Industries May Affect the Occurrence of Disinfection By-Products in Tap Water

Formation and occurrence of disinfection byproducts of benzodiazepine drug estazolam in drinking water of Beijing

Estazolam (EZ) is a long-acting benzodiazepine (BZD) drug with high clinical consumption in China to treat anxiety, depression and other syndromes. Recently, it has been found as a leading potentially inappropriate medication among hospitalized elderly patients, increasing the risk of falls. It is discharged into the aquatic environment after use and has been frequently detected, ultimately affecting the safety of drinking water. In the present study, the reaction of EZ during chlorination disinfection was investigated in detail with regard to its transformation and kinetics. By means of ultra-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-QTOF-MS), four main disinfection byproducts (DBPs) were tentatively identified, and the transformation pathways were speculated to be cleavage at the imine linkage and oxidation on the diazepinone ring. The chlorination reaction rate in the pseudo-first-order kinetic model was significantly affected by free available chlorine (FAC) and pH. The increase in pH value led to a decrease in the reaction rate, while a higher dosage of chlorine resulted in a faster kinetic rate. We further estimated the potential toxicities of EZ and its DBPs using quantitative structure-activity relationship (QSAR) software tools. DBPs exhibited much higher toxicity than EZ and exhibited developmental toxicity and mutagenicity. Finally, a total of 108 drinking water samples were collected in the wet and dry seasons to determine actual residue changes in real environmental conditions. The detection frequency was 29% for EZ, and the highest concentration of 0.60 ng L−1 was found for its DBPs in tap water. No seasonal variations in concentration were observed. Overall, the results indicate that EZ and its DBPs may persist in drinking water, posing potential risks to public health.

Evaluation of multiple disinfection by-products in tap, filtered and bottled water in Barcelona, Spain

BACKGROUND AND AIM: The formation of disinfection by-products (DBPs) as an unintended consequence of drinking water potabilization is a current global concern due to their potential relation to chronic diseases. With the aim of assessing human exposure to DBPs in drinking water, we quantified 4 trihalomethanes (THMs), 11 haloacetic acids (HAAs), 4 haloacetonitriles (HANs), chlorate, chlorite, 1,1-dichloropropanone (DCP), 1,1,1-trichloropropanone (TCP) and chloropicrin, in different drinking water types in Barcelona, Spain. METHODS: DBPs and physicochemical parameters such as conductivity and total organic carbon (TOC), were measured in tap water samples collected at 42 households, and in tap water filtered with activated carbon (AC) (N=6) and reverse osmosis (RO) (N=5). Selected DBPs were also analyzed in 10 popular bottled water brands. RESULTS:All tap water samples contained THMs and HANs, and 98% contained HAAs and chlorate above the limit of quantification (LOQ). Chlorite and TCP were found in 62 and 36% of the tap water samples, respectively, while DCP and chloropicrin were not detected. The median and interquartile range of total THMs, HAAs, HANs, and chlorate in tap water, calculated using values LOQ, were 42.0 (37.5-48.5), 18.0 (10.5-30.3), 3.2 (2.6-3.9), and 214 (159-296) µg/L, respectively. Conductivity was negatively correlated with bromodichloromethane (R=-0.91), TOC (R=-0.83), total HAAs (R=-0.82), dichloroacetonitrile (R=-0.78), TCP (R=-0.75), chlorite (R=-0.70), and positively correlated with the bromine incorporation factor (BIF) of THMs (R=0.82), DXAA (R=0.66), and TXAA (R=0.65) (X=Br/Cl). Both AC and RO filters reduced DBPs in tap water and none of the analyzed DBPs were detected in bottled water. CONCLUSIONS:THMs and HAAs were below the EU regulatory limits (Drinking Water Directive 2020/2184). A clear geographical pattern for most DBPs and for the conductivity was found, driven by the water source. With the generated data, we will develop predictive models based on routine monitoring parameters that could be applied in epidemiological research. KEYWORDS: Water quality, Chemical exposures, Exposure assessment, Multi-pollutant

The identification of halogenated disinfection by-products in tap water using liquid chromatography–high resolution mass spectrometry

In this paper, a comprehensive method for the identification of the unknown halogenated DBPs (X-DBPs, X = Cl, Br, and I) in the tap water of Wuhan, China via liquid chromatography-high resolution mass spectrometry (LC-HRMS) was developed. 123 X-DBPs were identified through the stepwise procedure, 94 of them were newly identified, and 3 of them were confirmed by standards. Most X-DBPs were aliphatic compounds and highly unsaturated and phenolic compounds, some X-DBPs contained multiple halogen atoms and rich in carboxyl groups, such as C2H2O2BrCl, C2H2O2Br2, and C2H2O2ClI. It was worth noting that the concentration of some X-DBPs had the same trend with time. Most Cl-DBPs remained stable and I-DBPs were detected occasionally by monitoring the change of concentration of these X-DPBs with the time during three consecutive months. The results demonstrate that the proposed method could provide valuable molecular formula and structure information on unknown multiple halogenated DBPs, or be used for the identification of other multiple halogenated organic compounds in different media.

Comparative cytotoxicity of halogenated aromatic DBPs and implications of the corresponding developed QSAR model to toxicity mechanisms of those DBPs: Binding interactions between aromatic DBPs and catalase play an important role

Halogenated aromatic disinfection byproducts (DBPs) are a new group of emerging DBPs identified recently. They have been detected in disinfected drinking water, wastewater effluents, recreational water and oil/gas produced water, at concentrations of ng/L to μg/L in general. Previously studies have demonstrated that most of them can induce developmental toxicity and growth inhibition in aquatic organisms based on in vivo bioassays. In this study, to further understand the adverse effects of aromatic DBPs to human health, the comparative cytotoxicity of 15 halogenated aromatic DBPs belonging to four subgroups (i.e., halophenols, halonitrophenols, halohydroxybenzaldehydes and halohydroxybenzoic acids) was evaluated with mammalian Chinese Hamster Ovary cells. The results indicated that the selected aromatic DBPs exhibited an in vitro toxicity rank order of halonitrophenols > halophenols > halohydroxybenzaldehydes > halohydroxybenzoic acids. The potential toxicity mechanisms involved with the antioxidant system were investigated by using molecular docking analysis between key antioxidant enzymes (i.e., catalase, superoxide dismutase, and glutathione S-transferase) and aromatic DBPs. Based on the observed cytotoxicity data and screening the candidate descriptors (including binding energies between the aromatic DBPs and key antioxidant enzymes as well as physical-chemical/quantum-chemical/topological descriptors), a QSAR model was developed as log (LC50) −1 = − 1.050ECAT + 0.300EHOMO − 0.238ELUMO− 0.164, indicating the importance of the interactions of aromatic DBPs towards catalase and the electrophilic/nucleophilic reactivity of aromatic DBPs in the toxicity mechanisms. In addition, the occurrence of the aromatic DBPs in tap water and finished water was studied in a mega city Shenzhen located in South China. Results showed that halogenated aromatic DBPs commonly existed in Shenzhen drinking water at ng/L levels, and three nitrogenous aromatic DBPs were detected in real drinking water for the first time. The major toxicity drivers among the target aromatic DBPs were identified through the integration of the measured concentrations and observed cytotoxicity; notably, DBPs with the highest concentrations may not contribute the highest proportions of overall toxicity.

A Tale of Two Water Supplies in China: Finding Practical Solutions to Urban and Rural Water Supply Problems.

Access to safe drinking water is among the 17 United Nations sustainable development goals. As the largest developing country, China has confronted large challenges to providing safe and sufficient drinking water to its population of 1.4 billion under the conditions of limited water sources and ubiquitous water contamination. This Account outlines these challenges as well as the practical solutions implemented by Chinese water professionals. We first provide a general introduction of the water supply in China. Next, we describe the main challenges of water source shortages and source water contamination. The practical solutions developed by Chinese water professionals are the core part of this Account, to which we have devoted ourselves to and contributed in some issues and cases. The water supply in China is a binary system that reflects the gap between urban and rural communities. Both urban and rural water supplies have been subject to water source shortages and contamination. Water shortages are mainly solved by long-distance water transportation projects. Urban water utilities generally pay attention to organic matter, ammonia, algae, and chemical spills in source water while also focusing on micro-organisms and disinfection byproducts in tap water. Micro-organisms are a widespread concern for rural water supplies, whereas arsenic, fluoride, and ammonia are an endemic concern in some rural communities. Investment in updating of treatment processes significantly benefits urban water supplies, and advanced treatment of ozonation and biologically activated carbon processes are now commonly used to ensure that strict drinking water quality standards are met. However, this is not the case for rural water supplies, where expensive advanced treatment is not affordable. Thus, improving rural water supplies requires approaches such as searching for sources with better water quality, using automated ultrafiltration instruments, or connecting to urban water supply distribution systems. For rural areas with high concentrations of arsenic or fluoride in source water, specific adsorbents are a practical way to help farmers. Similar challenges will be encountered elsewhere in the world; therefore, the practical solutions applied in China will be useful to other countries in different stages of development.

Conversion of haloacid disinfection byproducts to amino acids via ammonolysis

Haloacetic acids (HAAs) are the major disinfection byproducts (DBPs) that are formed during chlorination of drinking water. In this paper, the conversion of HAAs to amino acids (e.g., glycine) via ammonolysis was studied. First, a new and sensitive method for detecting glycine was developed by setting selected ion recording m/z 76 in positive electrospray ionization mass spectrometry coupled with ultra performance liquid chromatography. Second, among the mono-HAAs under the same test conditions, iodoacetic acid (49.3%) showed a considerably higher conversion to glycine during ammonolysis than chloroacetic acid (4.2%) and bromoacetic acid (27.7%). The conversion of iodoacetic acid to glycine increased with increasing temperature, increasing reaction time, or decreasing the ratio of (NH4)2CO3 to NH3·H2O in the aminating agent. Hydrolysis of iodoacetic acid to glycolic acid was also observed during ammonolysis, and it accounted for at most 50% of the iodoacetic acid conversion. The conversion to amino acids and the hydrolysis were the two major pathways during ammonolysis of HAAs. Third, compared with the iodoacetic acid sample and the simulated tap water sample without ammonolysis, the developmental toxicity of the corresponding samples with ammonolysis decreased by up to 10.4% and 32.1%, respectively. The ammonolysis was thus demonstrated to be a detoxification process for both individual HAAs and DBP mixture in chlorinated tap water. In practice, the ammonolysis of haloacid DBPs in tap water may be realized by simply adding an appropriate amount of an aminating agent during cooking.

DBPs in a chlorinated indoor swimming pool: occurrences and modeling

Swimming pool water contains higher chlorine residual and is maintained at a higher temperature than tap water. It constitutes environments with high levels of disinfection byproducts (DBPs) in water and air due to continuous disinfection and constant organic loading from the bathers. Exposure to DBPs is inevitable for any bather or trainer while such exposure can have cancer and non-cancer risks to humans. In this study, DBPs in tap water (S1) and water and air from a chlorinated indoor swimming pool before (S2) and after swimming (S3) were measured. Trihalomethanes (THMs) in S2 and S3 were 3.0–6.8 and 4.0–10.3 times the THMs in S1, respectively; and haloacetic acids (HAAs) in S2 and S3 were 2.3–4.3 and 2.5–5.5 times the HAAs in S1, respectively. THMs in air before swimming (S2-A) and after swimming (S3-A) were 60.4 and 77.5 μg/m 3 , respectively. Models were developed for predicting dissolved organic carbon, THMs and HAAs in swimming pool. The models showed good to excellent performance (R 2 = 0.70–0.87). The model validation studies showed moderate to good performance ( r = 0.73–0.83). The models might be useful in predicting DBPs9 exposure in swimming pools.

Predicting bromide incorporation in a chlorinated indoor swimming pool.

The water in and air above swimming pools often contain high levels of disinfection byproducts (DBPs) due to chemical reactions between chlorine- or bromine-based disinfectants and organic/inorganic matter in the source water and released from swimmers. Exposure to these DBPs, though inevitable, can pose health threats to humans. In this study, DBPs in tap water (S1), and water from a chlorinated indoor swimming pool before (S2) and after swimming (S3) were measured. The brominated species constituted the majority of DBPs formed in S1, S2, and S3. Trihalomethanes (THMs) in S3 was 6.9 (range 2.9-11.1) and 1.4 (range 0.52-2.9) times those in S1 and S2, respectively; and the haloacetic acids (HAAs) in S3 was 4.2 (range 2.5-7.5) and 1.2 (range 0.6-2.6) times those in S1 and S2, respectively. The mean THMs in air above the swimming pool before (S2-A) and after swimming (S3-A) were 72.2 and 93.0μg/m(3), respectively, and their ranges were 36.3-105.8 and 44.1-133.6μg/m(3), respectively. The average percentages of bromide incorporation (BI) into THMs in S1, S2, and S3 were 3.0, 9.3, and 10.6%, respectively; and the BI into HAAs in S1, S2, and S3 were 6.6, 12.0, and 12.2%, respectively. Several models were trained for predicting the BI into THMs and HAAs. The results indicate that additional information is required to develop predictive models for BI in swimming pools.

Effects of plumbing systems on human exposure to disinfection byproducts in water: a case study

Disinfection byproducts (DBPs) in water distribution systems (WDS) are monitored for regulatory compliance, while populations are exposed to DBPs in tap water that may be different due to stagnation of water in plumbing pipes (PP) and heating in hot water tanks (HWT). This study investigated the effects of water stagnation in PP and HWT on exposure and risk of DBPs to humans. Trihalomethanes (THMs) in PP and HWT were observed to be 1.1-2.4 and 1.6-3.0 times, respectively, to THMs in the WDS, while haloacetic acids (HAAs) were 0.9-1.8 and 1.2-1.9 times, respectively, to HAAs in the WDS. The chronic daily intakes of DBPs from PP and HWT were 0.6-1.8 and 0.5-2.3 times the intakes from WDS. The cancer risks from PP and HWT were 1.46 (0.40-4.3) and 1.68 (0.35-5.1) times the cancer risks from WDS. The findings may assist in regulating DBPs exposure concentrations.

Whole pictures of halogenated disinfection byproducts in tap water from China’s cities

When bromide/iodide is present in source water, hypobromous acid/hypoiodous acid will be formed with addition of chlorine, chloramine, or other disinfectants. Hypobromous acid/hypoiodous acid undergoes reactions with natural organic matter in source water to form numerous brominated/iodinated disinfection byproducts (DBPs). In this study, tap water samples were collected from eight cities in China. With the aid of electrospray ionization-triple quadrupole mass spectrometry by setting precursor ion scans of m/z 35, m/z 81, and m/z 126.9, whole pictures of polar chlorinated, brominated, and iodinated DBPs in the tap water samples were revealed for the first time. Numerous polar halogenated DBPs were detected, including haloacetic acids, newly identified halogenated phenols, and many new/unknown halogenated compounds. Total organic chlorine, total organic bromine, and total organic iodine were also measured to indicate the total levels of all chlorinated, brominated, and iodinated DBPs in the tap water samples. The total organic chlorine concentrations ranged from 26.8 to 194.0 μg·L−1 as Cl, with an average of 109.2 μg·L−1 as Cl; the total organic bromine concentrations ranged from below detection limit to 113.3 μg·L−1 as Br, with an average of 34.7 μg·L−1 as Br; the total organic iodine concentrations ranged from below detection limit to 16.4 μg·L−1 as I, with an average of 9.1 μg·L−1 as I; the total organic halogen concentrations ranged from 31.3 to 220.4 μg·L−1 as Cl, with an average of 127.2 μg·L−1 as Cl.

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.

7th International Symposium on Enabling Technologies for Life Sciences (ETP)

7^th International Symposium on Enabling Technologies for Life Sciences (ETP)

Speciation of common volatile halogenated disinfection by-products in tap water under different oxidising agents

A simple and efficient method has been developed for the extraction and determination of sixteen common volatile halogenated disinfection by-products (DBPs) using the static headspace (HS) technique coupled with gas chromatography–mass spectrometry (GC–MS). The DBPs determined included trihalomethanes (THMs), halonitromethanes (HNMs) and haloacetonitriles (HANs). The extraction parameters (HS conditions, ionic strength and organic modifier) were studied in order to obtain the highest sensitivity. Under optimum conditions (water containing 250μL of methyl tert-butyl ether and 6g of anhydrous sodium sulphate was heated 20min at 80°C), the HS–GC–MS method provides limits of detection between 10 and 200ng/L and a relative standard deviation of ∼5.6%. Samples collected from genuine tap water treated with different oxidising agents (ClO2/Cl2, Cl2/NH2Cl and O3/Cl2) in several disinfection treatment plants were successfully analysed in order to establish their effect on the occurrence of DBPs. In parallel, the influence of the main parameters of the water (pH, conductivity, nitrite, nitrate, free residual chlorine, permanganate oxidability and bromide) was also studied. The results suggest that the permanganate oxidability (related to organic matter) and the bromide concentration as well as disinfection conditions are directly related to the occurrence of THMs, HNMs and HANs, both in their concentrations and speciation. The method developed was compared to the reference EPA Method 551.1 for the analysis of tap water.

Occurrence and distribution of organic trace substances in waters from the Three Gorges Reservoir, China

This study deals with the evaluation of water quality of the Three Gorges Reservoir (TGR) in order to assess its suitability as a raw water source for drinking water production. Therefore, water samples from (1) surface water, (2) tap water, and (3) wastewater treatment plant effluents were taken randomly by 2011-2012 in the area of the TGR and were analyzed for seven different organic contaminant groups (207 substances in total), applying nine different analytical methods. In the three sampled water sources, typical contaminant patterns were found, i.e., pesticides and polycyclic aromatic hydrocarbons (PAH) in surface water with concentrations of 0.020-3.5 μg/L and 0.004-0.12 μg/L, disinfection by-products in tap water with concentrations of 0.050-79 μg/L, and pharmaceuticals in wastewater treatment plant effluents with concentrations of 0.020-0.76 μg/L, respectively. The most frequently detected organic compounds in surface water (45 positives out of 57 samples) were the pyridine pesticides clopyralid and picloram. The concentrations might indicate that they are used on a regular basis and in conjunction in the area of the TGR. Three- and four-ring PAH were ubiquitously distributed, while the poorly soluble five- and six-ring members, perfluorinated compounds, polychlorinated biphenyls, and polybrominated diphenyl ethers, were below the detection limit. In general, the detected concentrations in TGR are in the same range or even lower compared to surface waters in western industrialized countries, although contaminant loads can still be high due to a high discharge. With the exception of the two pesticides, clopyralid and picloram, concentrations of the investigated organic pollutants in TGR meet the limits of the Chinese Standards for Drinking Water Quality GB 5749 (Ministry of Health of China and Standardization Administration of China 2006) and the European Union (EU) Council Directive 98/83/EC on the quality of water intended for human consumption (The Council of the European Union 1998), or rather, the EU Directive on environmental quality standards in the field of water policy (The European Parliament and The Council of the European Union 2008). Therefore, the suggested use of surface water from TGR for drinking water purposes is a valid option. Current treatment methods, however, do not seem to be efficient since organic pollutants were detected in significant concentrations in purified tap water.

The Effect of Different Boiling and Filtering Devices on the Concentration of Disinfection By-Products in Tap Water

Disinfection by-products (DBPs) are ubiquitous contaminants in tap drinking water with the potential to produce adverse health effects. Filtering and boiling tap water can lead to changes in the DBP concentrations and modify the exposure through ingestion. Changes in the concentration of 4 individual trihalomethanes (THM4) (chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)), 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, an electric kettle, a saucepan, and a microwave were used. Samples were taken before and after each treatment to determine the change in the DBP concentration. pH, conductivity, and free/total chlorine were also measured. A large decrease of THM4 (from 48% to 97%) and MX concentrations was observed for all experiments. Bromine-containing trihalomethanes were mostly eliminated when filtering while chloroform when boiling. There was a large decrease in the concentration of bromate with reverse osmosis, but there was a little effect in the other experiments. These findings suggest that the exposure to THM4 and MX through ingestion is reduced when using these household appliances, while the decrease of bromate is device dependent. This needs to be considered in the exposure assessment of the epidemiological studies.

Modeling DBPs formation in drinking water in residential plumbing pipes and hot water tanks

Disinfection byproducts (DBPs) in municipal supply water are a concern because of their possible risks to human health. Risk assessment studies often use DBP data in water distribution systems (WDS). However, DBPs in tap water may be different because of stagnation of the water in plumbing pipes (PP) and heating in hot water tanks (HWT). This study investigated occurrences and developed predictive models for DBPs in the PP and the HWT of six houses from three municipal water systems in Quebec (Canada) in a year-round study. Trihalomethanes (THMs) in PP and HWT were observed to be 1.4–1.8 and 1.9–2.7 times the THMs in the WDS, respectively. Haloacetic acid (HAAs) in PP and HWT were observed to be variable (PP/WDS = 0.23–2.24; HWT/WDS = 0.53–2.61). Using DBPs occurrence data from these systems, three types of linear models (main factors; main factors, interactions and higher orders; logarithmic) and two types of nonlinear models (three parameters Logistic and four parameters Weibull) were investigated to predict DBPs in the PP and HWT. Significant factors affecting DBPs formation in the PP and HWT were identified through numerical and graphical techniques. The R 2 values of the models varied between 0.77 and 0.96, indicating excellent predictive ability for THMs and HAAs in the PP and the HWT. The models were found to be statistically significant. The models were validated using additional data. These models can be used to predict DBPs increase from WDS (water entry point of house) to the PP and HWT, and could thereby help gain a better understanding of human exposure to DBPs and their associated risks.

Variability and predictors of changes in water use during pregnancy

Disinfection by-products in tap water have been found in some studies to be associated with adverse pregnancy outcomes, but little is known about how water use and consumption might change during early pregnancy. Estimating water-related activities only at one time during pregnancy could easily lead to exposure misclassification. To evaluate changes in water use among pregnant women, we used data from a large epidemiologic study in which 1990 women were interviewed around 9 and 20 weeks' gestation. The water variables that were examined included ingestion of cold and hot tap water as well as of bottled water, showering and bathing. Changes were detected between early and mid-pregnancy for ingested cold tap water and showering. Thirty-three percent of the subjects changed cold-water ingestion by > or =1.0 liters/day and 44% changed their time showering by > or =35 min per week during this period. Increases in cold tap water intake were associated with age >35 years, income < $40,000, and non-Hispanic white ethnicity. We also found that the proportion of the total variation due to within-subject variability was 62% for hot tap water ingestion but only 35% for showering and approximately 50% for cold tap water, bottled water and bathing. Limited resources in epidemiologic studies often require a decision between collecting data for a large number of people or collecting multiple measurements for a smaller number of people. The results in this study will be useful to researchers who need to determine where to invest their effort when assessing water-related exposures and should help in evaluation of previously performed studies.