Concentrations Of Trihalomethanes Research Articles

Evaluation of Trihalomethane Formation Risk Analysis in Swimming Pools in Eskisehir, Turkey

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.

Flume and single-pass washing systems for fresh-cut produce processing: Disinfection by-products evaluation

Free chlorine is widely used in fresh-cut produce washing to minimize microbial cross-contamination, but its application can also lead to the formation of harmful disinfection byproducts (DBPs). This study compared DBPs in process water and washed produce during commercial operation. Samples of shredded lettuce and diced cabbages washed in chlorinated water in the traditional double-flume wash and novel immersion-free single-pass wash systems were collected at multiple time points and locations from the processing lines. A suite of 33 conventional and emerging DBPs, including 4 trihalomethanes (THMs), 9 haloacetic acids (HAAs), 9 nitrogenous DBPs (N-DBPs), and 11 carbonaceous DBPs (C-DBPs), were investigated. Overall, N-DBPs and HAAs dominated the concentration of detected DBPs. Wash water in the flumes contained 7–111 folds higher DBP levels compared to that in the single-pass system, with the abundance of DBPs following the order of N-DBPs > HAAs > C-DBPs > THMs. DBPs were detected on washed produce, presenting primarily in the forms of N-DBPs and HAAs followed by C-DBPs and THMs. While higher levels of DBPs were detected in flume-washed produce, the final potable water rinse significantly reduced the DBP concentration in these products. The concentrations of THMs and HAAs on these washed products were used to estimate potential exposure via consumption of fresh-cut produce and the levels were below the daily allowable exposure for drinking water standard established by the U.S. Environmental Protection Agency. The detected high concentration and potential toxicity of N-DBPs indicate the need for further research. The findings of this study advance the understanding of the formation and removal of DBPs during wash processes, and identify additional research opportunities for further reduction in DBPs and food safety improvement.

Influence of manganese oxide‐coated granular media on disinfection byproduct formation

AbstractThe objective of this study was to determine the influence of manganese oxide (MnOx) coated granular media on disinfection byproduct (DBP) formation for dissolved manganese (Mn(II)) and natural organic matter (NOM) concentrations typical in drinking water treatment (DWT). Instantaneous and 24‐h haloacetic acid and total trihalomethane concentrations of influent and effluent samples from two DWT plants, one using MnOx‐coated dual media (DM) filters and the other using second‐stage contactors for Mn(II) sorption by coarse MnOx‐coated ceramic media after DM filtration, were examined. Results showed that interaction with MnOx‐coated surfaces did not increase measured DBP concentrations. Observed increases in 24‐h DBP concentrations for the surface water plant were attributed to filter‐associated NOM, and not the MnOx coating. The findings of this study indicate that a second‐stage contactor – with MnOx‐coated media utilized for Mn(II) removal after a particle removal filter – does not increase DBP formation under typical treatment conditions.

Chlorination by-products in drinking water and risk of bladder cancer – A population-based cohort study

Chlorination by-products have been consistently associated with risk of bladder cancer in case-control studies, but confirmation from large-scale cohort studies is lacking. We assessed the association of drinking water trihalomethanes (THM), a proxy for chlorination by-products, with risk of bladder cancer in 58,672 men and women. Data came from two population-based cohorts, parts of the Swedish Infrastructure for Medical Population-Based Life-Course and Environmental Research (SIMPLER). Individual exposure to THM was assessed by combining residential information with tap water monitoring data. Participants were categorized into non-exposed, low (<15 µg/L) or high (≥15 µg/L) THM exposure. Incident cases were ascertained from 1998 through 2019 via register linkage. During 16 years of follow-up (965,590 person-years), 831 bladder cancer cases were ascertained. We observed no overall association of THM with risk of bladder cancer, hazard ratio for the highest exposed compared to the non-exposed 0.90 (95% confidence interval: 0.73 – 1.11). The null association remained after restricting the analysis to long-term residents and across strata of smoking status and cancer stage. Our results indicate that chlorination by-product exposure at THM concentrations representative of chlorinated drinking waters in most European countries, is not associated with an increased risk of bladder cancer.

Evaluation of formation and health risks of disinfection by-products in drinking water supply of Ggaba waterworks, Kampala, Uganda.

In developing countries, the evaluation of disinfection by-products in drinking water has been neglected because most water utility companies focus on microbial elimination. As a result, this study aimed at evaluating trihalomethane formation, the relation between water quality parameters and trihalomethane formation, and the estimation of the associated potential health risks in drinking water. The headspace purge and trap coupled with a gas chromatography-mass spectrometry technique was used to quantify trihalomethane. The concentrations of trihalomethane found in the water were within the National Water and Sewerage Corporation, World Health Organization guidelines, and the United States Environmental Protection Agency standards. Total organic carbon, ultraviolet absorbance at 254 nm, bromide concentration, and the temperature had a positive and significant correlation, pH had a positive but non-significant correlation, while the residual chlorine had a negative but significant correlation with trihalomethane formation. The potential health risk using the WHO index was 0.4, indicating no noncarcinogenic risk to human health in the study area. The lifetime carcinogenic risks of trihalomethane due to oral ingestion, dermal, and inhalation were 2.5×10-5, 9.1×10-6, and 8.3×10-6 for females and 2.4×10-5, 1×10-5, and 7.9×10-6 for males, and the values were within the USEPA acceptable low-risk range of 1×10-6<CR<5.1×10-5.

Modeling the formation of trihalomethanes in rural and semi-urban drinking water distribution networks of Costa Rica

Chlorination is one of the most important stages in the treatment of drinking water due to its effectiveness in the inactivation of pathogenic organisms. However, the reaction between chlorine and natural organic matter (NOM) generates harmful disinfection by-products (DBPs), such as trihalomethanes (THMs). In this research, drinking water quality data was collected from the distribution networks of 19 rural and semi-urban systems that use water sources as springs, surfaces, and a mixture of both, in three provinces of Costa Rica from April 2018 to September 2019. Twelve models were developed from four data sets: all water sources, spring, surface, and a mixture of spring and surface waters. Linear, logarithmic, and exponential multivariate regression models were developed for each data set to predict the concentration of total trihalomethanes (TTHMs) in the distribution networks. Concentrations of TTHMs were found between < 0.20 and 91.31µg/L, with chloroform being the dominant species accounting for 62% of TTHMs on average. Turbidity, free residual chlorine, total organic carbon (TOC), dissolved organic carbon (DOC), and ultraviolet absorbance at 254nm (UV254) showed a significant correlation with TTHMs. In all the data sets the linear models presented the best goodness-of-fit and were moderately robust. Four models, the best of each data set, were validated with data from the same systems, and, according to the criteria of R2, standard error (SE), mean square error (MSE), and mean absolute error (MAE), spring water and mixed spring/surface water models showed a satisfactory level of explanation of the variability of the data. Moreover, the models seem to better predict TTHM concentrations below 30µg/L. These models were satisfactory and could be useful for decision-making in drinking water supply systems.

Multi-exposure human health risks assessment of trihalomethanes in drinking water of Egypt

The present study aims to assess the probable lifetime cancer and non-cancer risks of exposure to the trihalomethanes in Egypt's drinking water through ingestion, dermal contact, and inhalation. A total of 1667 drinking water samples were collected from twenty-three Egyptian governorates over a three-years period. The concentrations of total trihalomethanes ranged between 29.07 and 86.01 μg/L and were always below the maximum contamination level recommended by the Egyptian standards (100 μg/L). Chloroform was the most prominent trihalomethanes species, while bromoform was rarely detected.The cancer risk study revealed that, among the investigated paths, inhalation poses the greatest risk. And bromodichloromethane had the highest impact to cancer (69%), followed by chlorodibromomethane (28%). Geographically, the highest cancer risk value was found in Matruh governorate (42.2 × 10−6) and the lowest was in Minya governorate (1.0 × 10−6). The cancer risk for the studied governorates, except Minya governorate, was higher than the level recommended by the USEPA (1.0 × 10−6).Hazard index (HI) study revealed that the ingestion pathway caused higher HI values than the dermal pathway and that chloroform had the highest contribution to HI value. However, the values of HI were below unity in all studied governorates demonstrating that there would be negligible non-cancer risk.

Effect of bromide on molecular transformation of dissolved effluent organic matter during ozonation, UV/H2O2, UV/persulfate, and UV/chlorine treatments

Ozonation and ultraviolet-based advanced oxidation processes (UV-AOPs) play important roles in advanced treatment of municipal wastewater for water reuse. Bromide is widely present in wastewater at different concentration levels (ranging from μg/L to mg/L). However, the effect of bromide on molecular transformation of dissolved effluent organic matter (dEfOM) in real wastewater during ozonation and UV-AOPs treatments still remains unclear. Herein, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was utilized to characterize the overall molecular transformation of dEfOM and the formation of unknown halogenated byproducts (X-BPs) in ozonation, UV/H2O2, UV/persulfate (UV/PS), and UV/chlorine (UV/Cl) processes in the presence of additional bromide. Compared with the same oxidation processes without additional bromide, the degree of dEfOM oxygenation had some extent decrement with the effect of bromide. A slightly increment of the number of unknown brominated byproducts (Br-BPs) was observed during ozonation, UV/H2O2, and UV/PS treatments in the presence of additional bromide, and the largest increment of these compounds was found in UV/Cl process. A total of 82 chlorinated byproducts (Cl-BPs) and 183 Br-BPs were detected in all oxidation processes with the effect of bromide, and the number of Br-BPs was significantly higher than that of Cl-BPs. Based on mass difference analysis, 69 pairs of possible precursors/Br-BPs were identified. In addition, the additional bromide did not remarkably increase the concentrations of trihalomethanes (THMs) and haloacetic acids (HAAs) in ozonation, UV/H2O2, and UV/PS treatments, while the production of THMs and HAAs significantly decreased by 68.06% and 54.55%, respectively, during UV/Cl treatment. The calculated cytotoxicity increased to some extent for each treatment, especially for UV/Cl treatment, and the compound with largest contribution to cytotoxicity was monobromoacetic acid. This study provides new insights into the formation and transformation of X-BPs during advanced treatment of real wastewater with the effect of bromide.

Trimester-specific associations of maternal exposure to disinfection by-products, oxidative stress, and neonatal neurobehavioral development.

Toxicological studies suggest that maternal exposure to disinfection by-products (DBPs) can impair fetal neurodevelopment. However, evidence from epidemiological studies is scarce and the underlying mechanisms remain unclear. To explore the trimester-specific associations between maternal blood trihalomethane (THM) and urinary haloacetic acid (HAA) concentrations and neonatal neurobehavioral development, and the potential mediating role of oxidative stress (OS). We included 438 pregnant Chinese women from the Xiaogan Disinfection By-Products (XGDBP) birth cohort. Biospecimens were repeatedly collected across trimesters and measured for blood THMs, urinary HAAs, and urinary OS biomarker concentrations. On the third day after birth, the Neonatal Behavioral Neurological Assessment (NBNA) test was administered to newborns. Associations of trimester-specific DBP measurements and OS biomarkers with neonatal NBNA scores were assessed using linear regression models with generalized estimating equations. The potential mediating role of maternal OS biomarkers was also investigated using mediation analyses. After adjusting for potential confounders, blood bromodichloromethane (BDCM) concentrations in the first trimester were inversely associated with NBNA scores [percent change comparing the extreme BDCM tertiles=-28.1% (95% CI: -55.2%, -0.88%); p for trend=0.043]. Besides, third-trimester urinary trichloroacetic acid (TCAA) concentrations were inversely associated with NBNA scores [percent change comparing the extreme TCAA tertiles=-32.9% (95% CI: -64.7%, -1.0%); p for trend=0.046]. These inverse associations differed across pregnancy trimesters (Type 3p-value=0.066 and 0.053, respectively) and were stronger in male infants and mothers aged≥25years. There was no evidence of mediating effect by 8-hydroxy-2-deoxyguanosine (8-OHdG), 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA), or 8-iso-prostaglandin F2α (8-isoPGF2α). Higher prenatal BDCM and TCAA concentrations during specific pregnancy trimesters were associated with lower NBNA scores. However, additional research is required to investigate underlying mechanisms.

Exposure to widespread drinking water chemicals, blood inflammation markers, and colorectal cancer.

Trihalomethanes (THMs) and nitrate are widespread chemicals in drinking water associated with colorectal cancer risk but mechanisms are not well understood. We explored the association between exposure to THMs and nitrate in drinking water and inflammation markers, and the link with colorectal cancer risk. A subset of 198 colorectal cancer cases and 205 controls from the multicase-control study MCC-Spain were included. Average concentration of THMs (chloroform, bromodichloromethane, dibromochloromethane, bromoform) and nitrate in tap water at the residence was estimated from age 18 until 2years before the interview ("long term") and for a recent period (3years before diagnosis). Serum levels of EGF, eotaxin, G-CSF, IL-17E, IL-1rA, IL-8, IP-10, MDC, MPO, periostin, VEGF, and C-reactive protein (CRP) were measured. We estimated the linear association between inflammation markers and exposure among controls, and the odds ratio of colorectal cancer associated with THM and nitrate exposure, and inflammation markers. A mediation analysis was conducted to identify inflammation markers in the pathway between THM/nitrate exposure and colorectal cancer. Serum concentrations of EGF, IL-8, IL-17E and eotaxin increased with recent residential levels of brominated THMs, chloroforom and/or total THM. No associations were observed for nitrate and for long-term residential THM levels. All residential exposures except chloroform were positively associated with colorectal cancer. Serum concentrations of VEGF and periostin were positively associated with colorectal cancer, while EGF was inversely associated. One protein-exposure combination (periostin-recent ingested brominated THMs) slightly mediated the association with colorectal cancer risk. Results suggest that estimated THM exposure is involved in inflammation processes. However, the study design was limited to stablish etiologically relevant associations between the protein levels and colorectal cancer risk. The lack of association between nitrate exposure and inflammation markers suggests other biological mechanisms are involved in the link with colorectal cancer.

Investigation of the formation and effects of upstream trihalomethanes in Tehran's raw and drinking water using the spectrophotometric method

Developing countries, such as Iran, lack the resources and infrastructure to effectively and continually monitor environmental variables related to safe drinking water. The concentration of trihalomethanes (THMs) in Tehran's drinking water was assessed using spectrophotometry as an alternative method rather than the commonly used GC–MS. This method proposes a more economical and available option for developing countries and local water treatment plants in small towns. Three surface water sites, i.e., the Karaj River, the Mamaloo River, the Jajrood River, and eighteen tap water sites, were logistically chosen to test this method. This study evaluates the effect of seasonal variables on trihalomethanes formation potential (THMFP) and its impact on drinking water THMs concentrations. According to the statistical analyses during summer, THMFP and temperature positively correlated with the correlation coefficient of 0.84 and P < 0.05. Also, a positive linear correlation was observed between THMFP and UV254 with a correlation coefficient of 0.73 and P < 0.05. THMFP started to decline during fall as the temperature decreased except in November when THMFP increased due to natural organic matters (NOMs) augmentation in rivers. The highest level of the monthly average concentration of THMs in drinking water was 33.9 ± 5.8 μg/L in September, and the lowest was 22.9 ± 4.2 μg/L in December. The results indicated a linear correlation between THMFP in surface water and THMs concentration in drinking water with a correlation coefficient of 0.81 and P < 0.05. This observation suggests that THMFP in surface water can directly affect THMs' levels in drinking water.

Probabilistic approach for health hazard assessment of trihalomethanes through successive showering events.

Trihalomethanes (THMs) are common disinfection by-products in chlorinated tap waters. They can cause various cancers and non-cancer health hazards. Ingestion, dermal contact, and inhalation are the three exposure routes considered in the THM hazard or risk assessments. Among these, inhalation hazard is generally calculated by assuming the initial concentration as zero. This assumption fails to address the case of continuous or successive showers that can happen in shared showering facilities such as student hostels or gymnasiums. In the present study, the leftover THM concentration from the previous bath was considered to assess the chronic daily intakes (CDI) and hazard index (HI) for successive showers. For this, tap water of a university campus was analyzed to understand the extent of THM exposure at consumer points and the result obtained was used for the hazard assessment. Total THM concentrations varied from 0.51 to 68.9µg L-1. To address the variability of the model input parameters, 50,000 iterations of Monte Carlo simulation were carried out. Maximum HI values of 7.94E - 02 ± 3.63E - 02, and 6.69E - 02 ± 3.08E-02 were observed for the 1st shower for females and males, respectively. This value increased exponentially up to the 5th shower and thereafter, the value was constant. The methodology followed in the present study successfully determines the risk and hazard of THMs through successive showers.

Association of blood trihalomethane concentrations with asthma in US adolescents: nationally representative cross-sectional study.

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.

Relationship between Blood Trihalomethane Concentrations and Serum Thyroid Function Measures in U.S. Adults.

Toxicological studies show that exposure to disinfection byproducts, including trihalomethanes (THMs), negatively affects thyroid function; however, few epidemiological studies have explored this link. This study included 2233 adults (ages ≥20 years) from the 2007-2008 National Health and Nutrition Examination Survey (NHANES) who were measured for blood THM concentrations [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), or bromoform (TBM)] and serum thyroid function biomarkers [thyroid-stimulating hormone, free thyroxine (FT4), total thyroxine (TT4), free triiodothyronine (FT3), total triiodothyronine (TT3), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb)]. Multivariable linear regression models showed positive associations between blood TCM, BDCM, and total THMs (the sum of all four THMs) concentrations and serum FT4, whereas inverse associations were found between blood DBCM and total brominated THM (Br-THM; the sum of BDCM, DBCM, and TBM) concentrations and serum TT3 (all p < 0.05). Besides, positive associations were observed between blood TCM concentrations and FT4/FT3 ratio, between BDCM, DBCM, and Br-THM concentrations and TT4/TT3 ratio, and between DBCM and Br-THM concentrations and FT3/TT3 ratio (all p < 0.05). Blood THM concentrations were unrelated to the serum levels of thyroid autoantibodies TgAb or TPOAb. In summary, exposure to THMs was associated with altered serum biomarkers of thyroid function but not with thyroid autoimmunity among U.S. adults.

Disinfection by-product formation and toxicity evaluation for chlorination with powered activated carbon

With the deterioration of source water quality, pre-chlorination and pre-addition of powdered activated carbon (PAC) have been widely applied to improve water treatment efficiency, which would lead to PAC exposure to chlorine. Although previous studies reported that some emerging carbon materials (e.g., graphene) could potentially act as disinfection by-product (DBP) precursors, there were few studies paying attention to the interaction between chlorine and the most commonly used carbon material-PAC on the DBP formation. In this study, the DBPs formed by chlorination with and without PAC were investigated, and the DBP toxicities in different systems were evaluated. The results showed that the PAC could react with chlorine and form trihalomethanes (THMs) and haloacetic acids (HAAs). The amount of surface oxygen groups of the PAC increased during the chlorination, with these oxygen groups, especially the meta-positioned –OH groups, facilitating the formation of THMs and HAAs. In the presence of NOM, lower concentrations of THMs and HAAs were observed in the systems with PAC than in those without PAC, demonstrating the critical role of PAC adsorption towards DBP control. The cytotoxicity evaluation indicated that more toxic reaction products between PAC and chlorine were formed besides conventional DBPs. Moreover, the PAC with higher BET surface area and more lactonic function groups formed less toxic DBPs during chlorination, which might reduce health risk for treatment processes with pre-chlorination.

Treatment of PPCPs and disinfection by-product formation in drinking water through advanced oxidation processes: Comparison of UV, UV/Chlorine, and UV/H2O2

The presence of pharmaceutical and personal care products (PPCPs) in water is concerning because of their potential threat to ecosystems and human health. Studies have indicated that these emerging contaminants cannot be effectively removed through conventional water treatment. In this study, the efficacy of various treatments - chlorination, ultraviolet (UV), UV/Chlorine, and UV/H2O2 processes - in PPCP removal from water was compared. The effects of reaction time, oxidant concentration, pH, and water matrix and the generation of disinfection by-products (DBPs) were also assessed. The removal of PPCPs was discovered to be superior when the concentration of oxidants was higher. In addition, pH affected the reactivity of chlorine with some of the investigated chemicals. Chorine itself plays a minor role in the UV/Chlorine process because it serves as a reactant for the generation of free radicals rather than oxidants. Matrix had a weak effect on the removal of PPCPs in the various treatment processes (mostly within 10%). UV could not effectively remove acetylsalicylic acid, ibuprofen, benzophenone, oxybenzone, caffeine, N,N-diethyl-meta-toluamide, or most estrogens. When chlorine or hydrogen peroxide (H2O2) was used with UV, the efficiency of removal of all selected PPCPs was greatly improved (≥56.5% for UV/Chlorine and ≥27.6% for UV/H2O2) within 5 min. Although the PPCP removal efficiency of UV/Chlorine was higher than that of UV/H2O2, UV/H2O2 resulted in smaller amounts of DBP formation in the treated water. By contrast, UV/Chlorine resulted in higher concentrations of trihalomethanes (21.6%), haloacetonitriles (29.4%), and haloketones (147.2%).

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

We measured the concentrations of Trihalomethanes (THMs), Chloroform (TCM), Bromodichloromethane (BDCM), Dibromochloromethane (DBCM) and Bromoform (TBM), in water, indoor air and exhaled air before and after using chlorine and ozone-chlorine disinfected swimming pools from September 2020 to January 2021. Two parallel panels of adult subjects swam for 60 min in a chlorine and an ozone-chlorine indoor swimming pool. The concentration of total THMs (tTHMs) in water samples of chlorine and ozone-chlorine swimming pools were in the ranges of 170.8–192.5 μg/L and 161.3–180.4 μg/L, respectively which exceeded the WHO guideline value. High levels of THMs were found in indoor air at the height of 10 cm compared to 150 cm above water surface. We found a statistically significant correlation between the concentration of THMs in water and indoor air samples. The results showed that the levels of all detected THMs in participant’ exhaled air after 60 min swimming were 11–13 times higher than those of before exposure. A statistically significant linear correlation was observed between THMs levels in the exhaled air and indoor air at the height of 10 cm above the water surface, but not with the levels at the height of 150 cm. We also found that the levels of THMs in exhaled air were associated with the energy expenditure, swimming distance and time, but not correlated with BMI and skin area.

Trihalomethanes in Water Supply System and Water Distribution Networks.

The formation of trihalomethanes (THMs) in natural and treated water from water supply systems is an urgent research area due to the carcinogenic risk they pose. Seasonal effects and pH have captured interest as potential factors affecting THM formation in the water supply and distribution systems. We investigated THM occurrence in the water supply chain, including raw and treated water from water treatment plants (coagulation, sedimentation, sand filtration, ClO2-disinfection processes, and distribution pipelines) in the Chiang Mai municipality, particularly the educational institute area. The effects of two seasons, rainy (September–November 2019) and dry (December 2019–February 2020), acted as surrogates for the water quality profile and THM occurrence. The results showed that humic acid was the main aromatic and organic compound in all the water samples. In the raw water sample, we found a correlation between surrogate organic compounds, including SUVA and dissolved organic carbon (DOC) (R2 = 0.9878). Four species of THMs were detected, including chloroform, bromodichloromethane, dibromochloromethane, and bromoform. Chloroform was the dominant species among the THMs. The highest concentration of total THMs was 189.52 μg/L. The concentration of THMs tended to increase after chlorination when chlorine dioxide and organic compounds reacted in water. The effect of pH on the formation of TTHMs was also indicated during the study. TTHM concentrations trended lower with a pH ≤ 7 than with a pH ≥ 8 during the sampling periods. Finally, in terms of health concerns, the concentration of TTHMs was considered safe for consumption because it was below the standard (<1.0) of WHO’s Guideline Values (GVs).

Association of blood trihalomethane concentrations with asthma among U.S. Children: NHANES 2005-2012

BACKGROUND AND AIM: Population studies show that use of swimming pools is associated with risk of asthma and allergic diseases among children. However, few studies have examined exposure to disinfection by-products (DBP) from water chlorination with risk of asthma. To explore the associations between blood trihalomethane (THM) concentrations (a biomarker of DBP) and asthma among U.S. children and assess to what extent the association is modified by tobacco smoke exposure. METHODS: We included 2,359 children aged 12-19 years with measured blood concentrations of four THMs at baseline: chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM) from the National Health and Nutrition Examination Surveys 2005-2012. Logistic regression models were fitted to assess the odds ratios (ORs) and 95% confidence intervals (CIs) for the association of THM concentrations (three or four categories) with the risk of self-reported lifetime and curent asthma. RESULTS:After adjusting for potential confounders, blood DBCM concentration was associated with a greater risk of ever asthma among all children (OR=1.54; 95% CI: 1.07, 2.21, comparing the extreme exposure categories). The relation was stronger among children exposed to tobacco smoke (OR=3.96; 95% CI: 1.89, 8.30, comparing the extreme exposure categories). We also found positive relationships between Br-THMs and risk of ever asthma (OR=3.28; 95% CI: 1.43, 7.53, comparing the extreme quartiles of exposure) and between DBCM and Br-THMs and risk of current asthma among children with tobacco smoke exposure (OR=3.72; 95% CI: 1.40, 9.89 and 3.79; 95% CI: 1.22, 11.79, resperctively, comparing the extreme exposure categories). CONCLUSIONS:Our findings provide novel evidence that exposure to disinfection by-products is associated with a greater risk of asthma in children, particularly among those exposed to tobacco smoke. KEYWORDS: Biomarkers of exposure, Water quality, Respiratory outcomes, Asthma, Environmental epidemiology

Chlorination by-products in drinking water and risk of bladder cancer – a population-based cohort study

BACKGROUND AND AIM: Exposure to chlorination by-products has been consistently associated with an increased risk of bladder cancer in case-control studies, but confirmation from large-scale cohort studies are lacking. We assessed the association of drinking water trihalomethanes (THM), a surrogate for chlorination by-products, with risk of bladder cancer in 58,672 men and women in two population-based cohorts. METHODS: We used data, including questionnaire information, from the Swedish Infrastructure for Medical Population-Based Life-Course and Environmental Research (SIMPLER). Individual exposure to THM was assessed by combining residential information from register with municipal THM monitoring data. Participants were categorized into no chlorination, low (15 µg/L) or high (15 µg/L) THM exposure dependent on their area of residence. Incident bladder cancer cases were ascertained from 1998 through 2019 via register linkage. Associations were examined using multivariable-adjusted Cox proportional hazards regression models, including information on smoking habits and drinking water arsenic concentrations. RESULTS:The mean THM concentration was 6.6 ± 2.2 µg/L and 17.1 ± 2.1 µg/L in the low and the high exposure category, respectively. During a mean follow-up of 16 years (965,590 person-years), 831 bladder cancer cases were ascertained. We observed no overall association of THM with risk of bladder cancer. The hazard ratio was 0.90 (95% confidence interval: 0.73 – 1.11) when comparing the highest exposed group with those in the non-chlorinated areas. The null association remained after restricting the analysis to long-term residents and across strata of smoking status and cancer stage. CONCLUSIONS:Our results suggest that at THM concentrations below 20 µg/L, which is representative of chlorinated drinking waters in most European countries, chlorination by-product exposure is not associated with risk of bladder cancer. KEYWORDS: Chlorination by-products, Disinfection by-products, Trihalomethanes, Bladder cancer, Water quality, Drinking water