A contribution to the problem of trihalomethane formation from the Arabian Gulf water

Swimming pools are popular entertainment and sport areas that people often use. For this reason, it is crucial to determine the physicochemical properties and Trihalomethanes (THMs) concentrations of swimming pools and the effect of THMs on swimmer health. This study focuses on the physicochemical parameters and THM concentrations of six swimming pools in Eskisehir and the impacts of THMs on human health. Within the study context, physicochemical parameters were examined and swimming pool water standards of various countries and organizations were evaluated. The alkalinity, pH, temperature, hardness, and free chlorine values of the swimming pools were determined to compare with the current standards. Concentrations of chloroform (TCM), bromodichloromethane (BDCM), and dibromochloromethane (DBCM) were also determined in the collected samples. Concentrations were found to be in the range of 11.6-100.1 µg/l for BDCM, 151.5-366.4 µg/l for TCM, ND-6.95 µg/l for DBCM, and 172.1-380.7 µg/l for TTHM. From the results, it was determined that TTHM concentrations were above the limit values defined by WHO, while chloroform (except P1 and P5 pools), BDCM (except P3 pool), and DBCM concentrations were significantly below the limit values. TTHMs and chloroform concentrations were high in tap water using sodium hypochlorite as a disinfectant. BDCM and DBCM concentrations were high in pools where groundwater was used. Health risks of THMs in pools through ingestion and dermal absorption were also estimated for both women and men. In the interpretation of the result, it was also found that high concentrations of TTHMs increased the risk, and women’s ingestion-based risk values are slightly higher than men’s ingestion-based risk values. Fingerprints of THM formation in pool water are precursor parameters and it is of great importance to constantly control and take precautions. It has been observed that the use of groundwater as a water source and NaCl as a disinfectant significantly reduces THM formation in swimming pools. However, in order to reduce the BDCM and DBCM concentrations in the use of groundwater, it is recommended to measure the precursor bromide and establish the relevant limit values. The use of hypochlorite disinfectants in pools where tap water is used as a water source increases THM formation. For this reason, it is necessary to determine the amount of organic carbon as a precursor for pools using tap water as a water source and add it to the limit values. In addition, the use of calcium hypochlorite disinfectant instead of sodium hypochlorite reduces THM formation. Highlight Physicochemical properties and THMs concentrations of swimming pools and effects of trihalomethanes (THMs) on the health of swimmers. Physicochemical parameters and THM concentrations of six swimming pools were determined, and the effects of THMs’ on human health. Physicochemical parameters (alkalinity, pH, temperature, and hardness), chloroform (TCM), bromodichloromethane (BDCM), and dibromochloromethane (DBCM) were studied. As a result of the study, total THMs and TCM concentrations were high in pools where tap water, and sodium hypochlorite were used. BDCM and DBCM concentrations were high in pools where groundwater was used. High THM concentrations increase the risk, and at the same time, women’s ingestion-based risk values are slightly higher than men’s ingestion-based risk values.

Disinfection by-products, specifically Trihalomethanes (THMs), are a common problem in Manitoba which uses mainly surface water as the source of drinking water. They are formed when disinfectants, such as chlorine, used to control microbial contaminants, react with organic content, which Manitoba`s surface water is rich in. THMs include four chemicals: Chloroform (CCl3), Bromodichloromethane (CCl2Br), Dibromochloromethane (CClBr2) and Bromoform (CBr3) (Oram, n.d.). Due to their dangerous health risks, such as cancer, the concentration of THMs in the water is regulated, and the guideline in Canada is of 100 µg/L (Health Canada, 2016). However, THM levels in Manitoba, especially along the distribution system, are extremely high and exceed the limit. Water treatment plants should minimize the levels of all disinfection by-products without reducing the effectiveness of the disinfection. There are many methods to combat the proliferation of THMs, such as reducing chlorination before filtering the water and reducing the precursors (organic material that reacts with chlorine and form THMs) in general. However, they only reduce the probability of THMs’ formation at the water treatment plant and are not being used in Manitoba. Therefore, this project presents aeration as a simple and effective post-treatment process to completely or almost completely remove THMs and meet the guidelines.

In this paper, spatial and temporal variations of trihalomethane (THM) concentrations were analyzed including chloroform trichloromethane (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and tribromomethane (TBM) in Yancheng City in Jiangsu Province, China. The water samples were collected monthly from January 2014 to January 2017 from four tap water sampling sites (S1, S2, S3, and S4) and two finished water sampling sites (WTP1 and WTP2) for THM analysis. The results showed that the mean concentrations during the study period for TCM, BDCM, DBCM, and TBM were 7, 15.9, 21, and 10.4μg/L in tap water samples and 3.2, 17.2, 22.7, and 10μg/L in finished water samples, which indicated that brominated THM concentrations were higher than chlorinated THM concentrations. The results of spatial analysis showed that THM concentrations in WTP1 were related to those in S1 and S4 and THM concentrations in WTP2 were related to those in S2 and S3. The concentrations of TCM, BDCM, and TBM have significant spatial variance, while DBCM and THM concentrations do not. The temporal analysis revealed that the highest THM concentration occurred in April, both in tap water and in finished water, which was also shown by temporal cluster analysis. The lowest THM concentration occurred in seasons with relatively lower temperature in all sampling sites. The results provide important information for environmental protection agencies and health care centers with emphasis on months with higher THM risk.

Trihalomethanes (THMs) are a class of disinfectant by-products present in chlorinated tap water. Mainly due to their carcinogenic potential, their concentration in drinking water is now limited by regulations. In Romania, little is known about their distribution in urban drinking water supply systems, their magnitude, or their seasonal variation. Drinking water suppliers periodically adapt and optimise their water treatment methods for economic reasons and in response to regulatory changes and technological developments. The formation of THMs is influenced by the physicochemical parameters of water (pH, temperature, total organic carbon—TOC) and by environmental factors (geographical, climatological). Most of these factors have significant seasonal variations that lead to the formation of THMs in variable concentrations. In this study, we analysed the seasonal trends in surface water quality (considering variations in temperature, pH, and TOC) and correlated them with the concentration of THMs in drinking water over two calendar years. Water samples were collected from the Arges River, in a geographical area comprised of plains. The results show that the formation of THMs is enhanced by increasing temperature over the course of a year, with the highest concentrations being obtained in July 2022 (98.7 µg/L THMs at 30.5 °C) and in August 2023 (81.9 µg/L THMs at 30.4 °C). The main parameters that trigger the formation of THMs are the organic matter content and the disinfectant dose; the pH has a moderate effect, and its effect is correlated with the concentration of organic matter. There were noted strong seasonal changes in the concentration of THMs, with the maximum peak being in the middle and late summer and the minimum peak being in winter. This indicates the possibility that the quality of drinking water may change as a result of climate change. In addition, monitoring and chlorination experiments have established that the concentration of THMs is directly proportional with the TOC.

Factors influencing formation of trihalomethanes in drinking water with special reference to Swedish conditions

Trihalomethanes (THMs) are byproducts of the process of disinfecting water with chlorine, in which, 4 compounds are most interested such as chloroform (CF), bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform (BF). These DBPs even at very low concentrations pose harmful health effects. These health risks may include cancers, reproductive disorders, birth defects and miscarriage. This study evaluates the 4 THMs in water supplied at 6 districts of Ho Chi Minh City and in swimming pool water at Tan Binh district. All samples were extracted by using liquid- liquid extraction method with n-hexane: diisopropylether (1:1) before analyzing by GC-ECD. The results showed that 4/4 THMs were found in water samples and 2/4 THMs (chloroform and bromodichloromethane) were found in swimming pool water samples. The results showed that there are differences in the THMs levels between sampling site. The average concentration of THMs in supplied water was 31.40 ±29.23 μg.L-1 (20 – 110 μg.L-1), in swimming pool water was 109.78 ± 15.21 μg.L-1 (90 – 140 μg.L-1). The sampling site which has the highest average concentration is Tan Phu district (102.45 ± 16.0 μg.L-1) and the lowest is district 1 (23.74 ± 1.92 μg.L-1). The results showed that the concentration of THMs in the supplied water and swimming pool water does not exceed the limit of national technical regulation on drinking water quality (QCVN 01: 2009/BYT), however, the chloroform concentration of some sampling sites exceeds the limit given by the Environmental Protection Agency (EPA).

This study focuses on the factors that affect trihalomethane (THMs) formation when dissolved organic matter (DOM) fractions (colloidal, hydrophobic, and transphilic fractions) in aqueous solutions were disinfected with chlorine. DOM fractions were isolated and fractionated from filtered lake water and were characterized by elemental analysis. The investigation involved a screening Placket-Burman factorial analysis design of five factors (DOM concentration, chlorine dose, temperature, pH, and bromide concentration) and a Box-Behnken design for a detailed assessment of the three most important factor effects (DOM concentration, chlorine dose, and temperature). The results showed that colloidal fraction has a relatively low contribution to THM formation; transphilic fraction was responsible for about 50% of the chloroform generation, and the hydrophobic fraction was the most important to the brominated THM formation. When colloidal and hydrophobic fraction solutions were disinfected, the most significant factors were the following: higher DOM fraction concentration led to higher THM concentration, an increase of pH corresponded to higher concentration levels of chloroform and reduced bromoform, higher levels of chlorine dose and temperature produced a rise in the total THM formation, especially of the chlorinated THMs; higher bromide concentration generates higher concentrations of brominated THMs. Moreover, linear models were implemented and response surface plots were obtained for the four THM concentrations and their total sum in the disinfection solution as a function of the DOM concentration, chlorine dose, and temperature. Overall, results indicated that THM formation models were very complex due to individual factor effects and significant interactions among the factors. In order to reduce the concentration of THMs in drinking water, DOM concentrations must be reduced in the water prior to the disinfection. Fractionation of DOM, together with an elemental analysis of the fractions, is important issue in the revealing of the quality and quantity characteristics of DOM. Systematic study composed from DOM fraction investigation and factorial analysis of the responsible parameters in the THM formation reaction can, after an evaluation of the adjustment of the models with the reality, serves well for the evaluation of the spatial and temporal variability in the THM formation in dependence of DOM. However, taking into consideration the natural complexity of DOM, different operations and a strict control of them (like coagulation/flocculation and filtration) has to be used to quantitatively remove DOM from the raw water. Assuming that this study represents a local case study, similar experiments can be easily applied and will supply with relevant information every local water treatment plant meeting problems with THM formation. The coagulation/flocculation and the filtration stages are the main mechanisms to remove DOM, particularly the colloidal DOM fraction. With the objective to minimize THMs generation, different unit operation designed to quantitatively remove DOM from water must be optimized.

BackgroundPopulation studies show that the use of swimming pools is associated with the risk of asthma and allergic diseases among children. Our objective was to explore the associations between blood trihalomethane (THM) concentrations and asthma among US adolescents, and assess to what extent the association is modified by active tobacco smoke exposure.MethodsWe included 2359 adolescents aged 12–19 years with measured blood concentrations of chloroform (trichloromethane (TCM)), bromodichloromethane (BDCM), dibromochloromethane (DBCM) and bromoform (tribromomethane (TBM)) from the National Health and Nutrition Examination Survey 2005–2012. Logistic regression models were fitted to assess the odds ratios for the association of blood THM concentrations (three or four categories) with the risk of self-reported current and ever (lifetime) asthma.ResultsBlood DBCM concentrations were associated with a higher risk of ever asthma among all adolescents (OR 1.54 (95% CI 1.07–2.21), comparing the extreme exposure categories). The relationship was stronger among adolescents exposed to tobacco smoke (OR 3.96 (95% CI 1.89–8.30), comparing the extreme exposure categories). We also found positive relationships between blood brominated THM concentrations (sum of BDCM, DBCM and TBM) and risk of ever asthma and between blood DBCM and brominated THM concentrations and risk of current asthma among adolescents with tobacco smoke exposure. The relative excess risk of ever asthma due to the interaction between high blood DBCM and brominated THM concentrations and tobacco smoke exposure was 1.87 (95% CI 0.30–3.43) and 0.78 (95% CI 0.07–1.49), respectively.ConclusionsExposure to THMs is associated with a higher risk of asthma in adolescents, particularly among those exposed to tobacco smoke.

Trihalomethanes in exhaled air, indoor air and water: A parallel design trial in chlorine and ozone-chlorine disinfected swimming pools

We are conducting an epidemiological study on the association between disinfection by-product concentrations in drinking water and adverse birth outcomes in the UK, using trihalomethane (THM) concentrations over defined water zones as an exposure index. Here we construct statistical models using sparse routinely collected THMs measurements to obtain quarterly estimates of mean THM concentrations for each water zone. We modelled the THM measurements using a Bayesian hierarchical mixture model, taking into account heterogeneity in THM concentrations between water originating from different source types, quarterly variation in THM concentrations and uncertainty in the true value of undetected and rounded measurements. Quarterly estimates of mean THM concentrations plus estimates of the water source type (ground, lowland surface or upland surface) were obtained for each water zone. THM concentration estimates were typically highest from July to September (third quarter), and varied considerably between water sources. Our exposure estimates were categorized into 'low', 'medium' and 'high' THM classes. Our modelled quarterly exposure estimates were compared to a simple alternative: annual means of the raw data for each water zone. In all, 15-25% of exposure estimates were classified differently. The modelled THM estimates led to slightly stronger and more precise estimates of association with risk of still birth and low birth weight than did the raw annual means. We conclude that our modelling approach enabled us to provide robust quarterly estimates of ecological exposure to THMs in a situation where the raw data were too sparse to base exposure assessment on empirical summaries alone.

Seasonal variability in source water can lead to challenges for drinking water providers related to operational optimization and process control in treatment facilities. The objective of this study is to investigate seasonal variability of water quality in municipal small water systems (<3000 residents) supplied by surface waters. Residual chlorine and trihalomethanes (THM) were measured over seven years (2003–2009). Comparisons are made within each system over time, as well as between systems according to the type of their treatment technologies. THM concentrations are generally higher in the summer and autumn. The seasonal variability was generally more pronounced in systems using chlorination plus additional treatment. Chloroform, total THM (TTHM) and residual chlorine concentrations were generally lower in systems using chlorination plus additional treatment. Conversely, brominated THM concentrations were higher in systems using additional treatment. Residual chlorine was highest in the winter and lowest in the spring and summer. Seasonal variations were most pronounced for residual chlorine in systems with additional treatment. There was generally poor correlation between THM concentrations and concentrations of residual chlorine. Further study with these data will be beneficial in finding determinants and indicators for both quantity and variability of disinfection byproducts and other water quality parameters.

Recommendations regarding disinfection by-products (DBPs) in pool waters consider the content of trihalomethanes (THMs) and combined chlorine (CC) as indicators of DBPs based on which the health risk for swimmers and staff of pool facility can be determined. However, the content of DBPs in swimming pools depends on many factors. In this paper, the influence of selected factors (physicochemical parameters of water and technological parameters) on the content of THMs and CC in pool water was determined. During the 6-month period, 9 pools of various functions were analyzed. The water in pools was subjected to the same method of treatment. The content of THMs and CC was compared against the content of organic matter, free chlorine and nitrates, pH, temperature, redox potential and turbidity, technological, and operational parameters. The THM content did not exceed the limit value of 0.1 mg/L. The content of CC varied significantly, from 0.05 to 1.13 mg Cl2/L. It was found that a very large water volume per person, in comparison to a very small one, contributed to the low content of CC and THMs. The high load expressed as m3 of water per person or m2 of water per person and the specific function of hot tubs (HT1 and HT2) led to the average concentration of CC in these pools exceeding 0.3 mg Cl2/L. The THM concentrations in hot tubs (especially in HT1) were also among the largest (0.038–0.058 mg/L). In terms of the analyzed microbiological indicators, the quality of the tested pool water samples was not in doubt. It was found that the purpose of the pool, its volume, and number of swimmers should be the key parameters that determine the choice of methods of water treatment. The research on the pool water quality in the actual working conditions of swimming pool facilities is necessary due to the need to preserve the health safety of swimmers and staff.

Some disinfection by-products (DBPs) in drinking water present a potential safety concern. This study focuses on the elements influencing DBPs formation. A total of 120 water samples were collected from 10 different drinking water facilities spanning 5 counties within Huzhou, Zhejiang Province, China. Concentrations of trihalomethanes (THMs) and haloacetic acids (HAAs) were observed to be 14.5 and 27.4 μg/L, respectively, constituting 34 and 64% of the total DBPs. Seasonal fluctuations demonstrated that HAAs, THMs, halonitromethanes (HNMs), and haloacetonitriles (HANs) followed a similar pattern with higher levels in summer or autumn compared to spring. Importantly, the concentrations of HAAs and THMs were markedly higher in Taihu-sourced water compared to other sources. Geographically, Nanxun exhibited the highest levels of total DBPs, HAAs, and THMs, while Deqing and Changxing demonstrated significantly lower levels. Correlation studies between water quality parameters and DBPs revealed that factors such as chloride content, temperature, and residual chlorine positively influenced DBPs formation, whereas turbidity negatively affected it. Principal component analysis suggested similar formation processes for HANs, haloketones (HKs), HNMs, and THMs. Factors such as temperature, chemical oxygen demand (COD), and residual chlorine were identified as significant contributors to the prevalence of HAAs.

Cancer risk assessment from exposure to trihalomethanes in tap water and swimming pool water

A visible colorimetric sensor based on nanoporous polypropylene fiber membranes for the determination of trihalomethanes in treated drinking water