Trihalomethanes In Water Research Articles

Disinfection byproducts in US drinking water and cancer mortality

ABSTRACT Trihalomethanes, the main drinking water disinfection byproducts, may be carcinogenic and are regulated to amaximum total trihalomethanes (TTHM) of 80 µg/l in the US. We aimed to determine whether total and individual trihalomethanes in drinking water across the US are associated with higher cancer mortality in 6,260 adult participants to the National Health and Nutrition Examination Surveys from 1999 to 2008 followed for mortality until 2019 (median: 14.4 years). At baseline, the geometric mean (standard error) of TTHM in drinking water was 9.61 (0.85) µg/l. During follow-up, 873 deaths occurred, including 207 from cancer. In Cox proportional hazards regression adjusted for relevant covariates, drinking water TTHM (HR: 1.45, 95% CI: 1.16–1.82), chloroform (HR: 1.35, 95% CI: 1.12–1.64), and bromodichloromethane (HR: 1.30, 95% CI: 1.05–1.59) were associated with 30% to 45% higher cancer mortality. Therefore, drinking water trihalomethanes, especially chloroform and bromodichloromethane maybe risk factors for cancer mortality.

Management of trihalomethanes in water by ZnO@kaolinite composite: integrated experimental and modeling studies.

The adsorption of trihalomethanes (THMs) from drinking water was investigated in the current study through comparison studies of kaolinite and ZnO@kaolinite nanocomposites. The clay structural network's successful immobilization on the zincite hexagonal structure of ZnO nanoparticles' lattice layers was verified by the SEM/EDX analysis. Under the optimum conditions, the maximum removal of THMs was achieved by kaolinite and ZnO@kaolinite nanocomposites after 60 min. The adsorption performance of the ZnO@kaolinite nanocomposites was greater than that of kaolinite because the former had a larger surface area than the latter. The Freundlich isotherm model best matched the adsorption experimental data, which also reveals the existence of multilayer adsorption on a diverse surface with the greatest correlation (R2 = 0.956 and 0.954, respectively) for both nanoadsorbents using the pseudo-first-order (PFO), pseudo-second-order (PSO), mixed 1, 2-order (MFSO), and intraparticle diffusion (IPD) models. The mechanism by which THMs in drinking water adsorb onto nanoadsorbents was examined. This revealed that both intraparticle and film diffusion were involved in the adsorption process. Kaolinite and ZnO@kaolinite nanocomposites can be used in water treatment to remove THMs due to their great recyclable and reusable properties, even after six cycles.

Exposure to Trihalomethanes and Bone Mineral Density in US Adolescents: A Cross-Sectional Study (NHANES).

Animal and human studies have suggested that trihalomethane (THM) has toxicity to bone. In this study, we included adolescents from the National Health and Nutrition Examination Survey who had quantified blood and tap water THM concentrations [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and lumbar spine or total body less head (TBLH) bone mineral density (BMD). A 2.7-fold increase in concentrations of blood TCM, DBCM, chlorinated THMs (the sum of TCM, BDCM, and DBCM), and total THMs (the sum of 4 THMs) was associated with lower lumbar spine BMD z-scores by -0.06 [95% confidence interval (CI): -0.12, -0.01], -0.06 (95% CI: -0.11, -0.003), -0.08 (95% CI: -0.14, -0.02), and -0.07 (95% CI: -0.13, -0.003), respectively, in adjusted models. Similarly, a 2.7-fold increase in blood BDCM, DBCM, and chlorinated THM concentrations was associated with lower TBLH BMD z-scores by -0.10 (95% CI: -0.17, -0.02), -0.10 (95% CI: -0.17, -0.03), and -0.11 (95% CI: -0.20, -0.01), respectively. Low-to-moderate predictive power was attained when tap water THM concentrations were used to predict blood THM measurements. Notably, the inverse associations for blood THMs persisted exclusively between water concentrations of DBCM and Br-THMs and the TBLH BMD z-scores. Our findings suggest that exposure to THMs may adversely affect the adolescent BMD.

Trihalomethanes in developed and developing countries.

The reactions between natural organic matter, anthropogenic contaminants, ions, and disinfectants lead to the formation of disinfection by-products (DBPs) such as trihalomethanes (THMs) in drinking water. The formation of THMs is strongly related to the chlorination of water. The study's central objective was to compare the concentration of THMs in twenty developed and developing countries and their disinfection techniques. The THM concentration in 11 developed and 9 developing countries ranged from 0.5 µg/L (Germany) to 215 µg/L (Russia) and 3 µg/L (China) to 439.2 µg/L (Bangladesh), respectively. The developed country has partially succeeded in reducing THM concentration in drinking water, whereas significant steps are needed in developing countries to reduce the existing high THM concentration. The concentration of THMs in water varies among these countries because of the different water sources, water quality, environmental conditions, and efficiency of water treatment technologies. A meaningful relationship has been observed between the properties of water and the THM formation. The use of chemical disinfectants will result in new forms of DBPs that are undesirable due to their carcinogenic and mutagenic effects on human health. The DBP guidelines by various national and international agencies have helped to control and manage the THM concentration in drinking water. However, these regulatory standards are not continuously monitored. Therefore, the formation of these compounds should be prevented either by removing THMs forming precursors or by using an integrated approach for controlling THM formation by implementing advanced water treatment technology. Extensive research is desirable in domains like THM minimization strategies which are easy to deploy, scalable, and cost-effective.

Fast and accurate isotope dilution mass spectrometry method for the assignment of trihalomethanes in water in an uncommon accuracy-based proficiency testing programme in Singapore

ABSTRACT In the light of the instability of trihalomethanes (THMs) in water, a fast and high accuracy method based on headspace gas chromatography-isotope dilution mass spectrometry (HS-GC-IDMS) technique was developed. The optimised method was validated using fortified water samples. Recoveries between 96.1% and 108.8% with an intermediate precision between 3.9% and 5.7% were achieved. The method was applied in the value assignment of THMs in water in an accuracy-based proficiency testing (PT) programme organised by the Health Sciences Authority (HSA) Singapore. The assigned values obtained for chloroform, bromodichloromethane, dibromochloromethane and bromoform were 73.6 ± 9.3 µg/L, 49.1 ± 5.2 µg/L, 47.7 ± 4.4 µg/L and 70.8 ± 6.8 µg/L, respectively. The PT programme was especially valuable and uncommon as it allowed local water testing laboratories to have access to traceable reference values for the benchmarking of their technical competencies. The procedure undertaken by the Laboratory to prepare a batch of PT sample comprising the unstable analytes, conduct homogeneity and stability testing, as well as value assignment, are presented. The between-samples relative standard deviations (RSDs) obtained in a feasibility batch of THMs concentrate in methanol were improved by four to six times compared to those from the first feasibility batch of THMs in water. Based on z-scores, evaluated using the assigned reference value determined by HS-GC-IDMS, 85% of the participating laboratories in the PT programme achieved satisfactory results. The provision of metrological assigned values heightened the testing laboratories’ awareness on the importance of accuracy-based PT programmes for evaluation of true method biases, which is particularly valuable for analytes with regulated limits.

Within-day variation and health risk assessment of trihalomethanes (THMs) in a chlorinated indoor swimming pool in China.

Trihalomethanes (THMs) are the most common species of disinfection by-products (DBPs) in swimming pools and have received widespread attention due to their risk to public health. However, studies examining within-day variation and the carcinogenic health risks from exposure to THMs in indoor swimming pools are limited. Our study aimed to detect the within-day variation of four THMs categories and carcinogenic health risk in indoor swimming pool water in Taiyuan, China, and to examine the correlations between THMs and environmental parameters. Our results showed chloroform (TCM) was the most abundant component in THMs with median concentrations from 0.038-0.118μg/m3. TCM and THMs were significantly positively correlated with FCl and significantly negatively correlated with the cumulative number of swimmers (CNS) in the swimming pool. The concentration of total THMs and TCM, lifetime average daily doses (LADD) of TCM, and the total lifetime cancer risks (ELCR) values of THMs declined with time with the highest level occurring at 8:00 am. ELCR values of THMs were in the range of 1.368 × 10-5-1.968 × 10-5, which exceeded the negligible risk level (10-6) defined by US EPA. Our results suggest that THM occurrence and the carcinogenic health risks in pool water varied temporally. Exposure to pool water THMs may pose a carcinogenic risk to human health, especially at the pool's opening time.

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.

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.

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.

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

Multivariate analysis of the distribution and formation of trihalomethanes in treated water for human consumption

The disinfection of water for human consumption with chlorine or other compounds produces secondary reactions with the organic matter, generating undesirable disinfection by-products (DBPs). Among these are trihalomethanes (THMs), identified as carcinogenic compounds. This work determined the trihalomethanes concentration, both speciated and total, in treated water distributed and stored in tanks of residential condominiums of different social classes. THMs were quantified using static manual Headspace as preconcentration technique, injecting the vapor phase collected in a GC/FID. The results show that the water distributed to the homes already contains THMs, trichloromethane being the major compound. The Principal Components Analysis (PCA) and Hierarchical Cluster Analysis (HCA) with 60 water samples showed that there is no significant distinction among samples of treated water distributed water and water stored in tanks. This study warns to the importance of controlling the formation of trihalomethanes in water throughout treatment and distribution for users.

Exposure to drinking water trihalomethanes and nitrate and the risk of brain tumours in young people

Brain tumours (BTs) are one of the most frequent tumour types in young people. We explored the association between tap water, exposure to trihalomethanes (THM) and nitrate and neuroepithelial BT risk in young people. Analysis of tap water consumption were based on 321 cases and 919 appendicitis controls (10–24 years old) from 6 of the 14 participating countries in the international MOBI-Kids case-control study (2010–2016). Available historical residential tap water concentrations of THMs and nitrate, available from 3 countries for 86 cases and 352 controls and 85 cases and 343 for nitrate, respectively, were modelled and combined with the study subjects’ personal consumption patterns to estimate ingestion and residential exposure levels in the study population (both pre- and postnatal). The mean age of participants was 16.6 years old and 56% were male. The highest levels and widest ranges for THMs were found in Spain (residential and ingested) and Italy and in Korea for nitrate. There was no association between BT and the amount of tap water consumed and the showering/bathing frequency. Odds Ratios (ORs) for BT in relation to both pre- and postnatal residential and ingestion levels of THMs were systematically below 1 (OR = 0.37 (0.08–1.73)) for postnatal average residential THMs higher than 66 μg/L. For nitrate, all ORs were above 1 (OR = 1.80 (0.91–3.55)) for postnatal average residential nitrate levels higher than 8.5 mg/L, with a suggestion of a trend of increased risk of neuroepithelial BTs with increasing residential nitrate levels in tap water, which appeared stronger in early in life. This, to our knowledge, is the first study on this topic in young people. Further research is required to clarify the observed associations.

Adsorption Studies of Waterborne Trihalomethanes Using Modified Polysaccharide Adsorbents.

The adsorptive removal of trihalomethanes (THMs) from spiked water samples was evaluated with a series of modified polysaccharide adsorbents that contain β-cylodextrin or chitosan. The uptake properties of these biodegradable polymer adsorbents were evaluated with a mixture of THMs in aqueous solution. Gas chromatography employing a direct aqueous injection (DAI) method with electrolytic conductivity detection enabled quantification of THMs in water at 295 K and at pH 6.5. The adsorption isotherms for the polymer-THMs was evaluated using the Sips model, where the monolayer adsorption capacities ranged between 0.04 and 1.07 mmol THMs/g for respective component THMs. Unique adsorption characteristics were observed that vary according to the polymer structure, composition, and surface chemical properties. The modified polysaccharide adsorbents display variable molecular recognition and selectivity toward component THMs in the mixed systems according to the molecular size and polarizability of the adsorbates.

Analysis of the Kinetics of Swimming Pool Water Reaction in Analytical Device Reproducing Its Circulation on a Small Scale.

The most common cause of diseases in swimming pools is the lack of sanitary control of water quality; water may contain microbiological and chemical contaminants. Among the people most at risk of infection are children, pregnant women, and immunocompromised people. The origin of the problem is a need to develop a system that can predict the formation of chlorine water disinfection by-products, such as trihalomethanes (THMs). THMs are volatile organic compounds from the group of alkyl halides, carcinogenic, mutagenic, teratogenic, and bioaccumulating. Long-term exposure, even to low concentrations of THM in water and air, may result in damage to the liver, kidneys, thyroid gland, or nervous system. This article focuses on analysis of the kinetics of swimming pool water reaction in analytical device reproducing its circulation on a small scale. The designed and constructed analytical device is based on the SIMATIC S7-1200 PLC driver of SIEMENS Company. The HMI KPT panel of SIEMENS Company enables monitoring the process and control individual elements of device. Value of the reaction rate constant of free chlorine decomposition gives us qualitative information about water quality, it is also strictly connected to the kinetics of the reaction. Based on the experiment results, the value of reaction rate constant was determined as a linear change of the natural logarithm of free chlorine concentration over time. The experimental value of activation energy based on the directional coefficient is equal to 76.0 . These results indicate that changing water temperature does not cause any changes in the reaction rate, while it still affects the value of the reaction rate constant. Using the analytical device, it is possible to constantly monitor the values of reaction rate constant and activation energy, which can be used to develop a new way to assess pool water quality.

Efficacy of Moringa oleifera Seed Husk as Adsorptive Agent for Trihalomethanes from a Water Treatment Plant in Southwestern, Nigeria

Trihalomethanes (THMs) are formed when excess chlorine during chlorination of water reacts with organic material in water. They have mutagenic and carcinogenic properties. Moringa oleifera (MO) has found wide acceptance by many people in Nigeria who have used it for food for both humans and fauna, for health purposes, and as a coagulant for water treatment. However, the seed husks are currently discarded as waste and they have not been used as adsorbent to remove THMs from water. The physicochemical properties of both the treated and raw surface water were determined using standard methods, and the concentration of THMs was determined from the water treatment plant at different stages of treatment using gas chromatography with flame ionization detector (GC-FID). Recovery experiments were carried out to validate the procedure. The efficiencies of activated carbon of Moringa oleifera seed husk (MOSH) adsorbent for the removal of THMs in the water and as a coagulant for water treatment were also assessed. Batch adsorption experiments were carried out, and different parameters such as pH (5, 7, and 9), adsorbent dosage (0.2, 0.4, and 0.8 g), contact time (30, 60, and 90 minutes), and initial concentration (0.2, 0.4, and 0.6 mg/l) were optimized for the removal of trichloromethane and tribromomethane using the MOSH activated carbon. Experimental adsorption data from different initial concentrations of trichloromethane and tribromomethane were used to test conformity with Langmuir and Freundlich adsorption isotherms. The percentage recovery from our procedures ranged from 96.0 ± 1.41 to 100.0 ± 0.00 for trichloromethane while for tribromomethane the range was 60 ± 2.82 to 100.0 ± 0.00. The mean percentage adsorption efficiencies for the simulation experiment ranged from 34.365 ± 1.41 to 93.135 ± 0.57 and from 41.870 ± 0.27 to 94.655 ± 0.41 for trichloromethane and tribromomethane, respectively. The optimum conditions for both trichloromethane and tribromomethane were pH 9, 0.8 g adsorbent dosage, 60-minute contact time, and 0.6 mg/l initial concentration. The optimum values of these parameters used for the adsorption of the two THMs in the surface water serving the treatment plant gave an efficiency of 100.00 ± 0.00%. The turbidity values for the coagulation experiment reduced from 9.76 ± 0.03 NTU in the raw water before coagulation to 5.92 ± 0.13 NTU after coagulation while all other physicochemical parameters of the surface water decreased in value except conductivity and total dissolved solid which increased from 104.5 ± 3.54 to 108.0 ± 2.83 μS/cm and 63.00 ± 11.31 to 83.0 ± 8.49 mg/l, respectively. The experimental data best fit into Langmuir than Freundlich adsorption isotherm. The study concluded that MOSH activated carbon could serve as an adsorbent for the removal of THMs, calcium, and sulphur from water samples.

Effect of visible light on the removal of trichloromethane by graphene oxide

In this experimental study, the degradation of disinfection by-products using graphene oxide was studied. Degradation of chloroform, which is the most common type of trihalomethanes in water, was investigated. Graphene oxide (GO) was synthesized by the Modified Hummers' Method. TEM images showed that the synthesized graphene oxide was exfoliated layer by layer and was very stable according to the zeta potential result. In the degradation studies; the effect of time, chloroform concentration and graphene oxide concentration were investigated both under visible light and under darkness. According to the experimental results, studies containing 100 μg/L trichloromethane and 250 mg/L GO were stabilized after 30 min and the removal of 70.6% for darkness increased to 98% under visible light. When the graphene oxide concentration is increased, it is seen that the positive effect of visible light increases from 22% to 30%. According to the isotherm and kinetic model research, it was found that the studies conducted in both conditions were appropriate to Freundlich isotherm and Pseudo second-order kinetic model. The maximum adsorption capacities based on Pseudo second-order kinetic modeling was obtained as 350 and 450 μg/g for darkness and visible light, respectively.

A cotton pad-based sensor for the detection and determination of trihalomethanes in water by the colorimetric method

Trihalomethanes in disinfected water samples can be detected and determined by a simple equipment.

The urban exposome framework and a proof-of-concept study

PDS 71: Exposome, Johan Friso Foyer, Floor 1, August 27, 2019, 4:30 PM - 5:30 PM Cities face rapid changes including increasing inequalities and public health issues. Therefore, urban centers should become more resilient, monitor and address all emerging issues with cost-effectively. Using the city and inter-city areas as measurement units, the urban exposome can be defined as the continuous spatiotemporal monitoring of environmental and health indicators with an interdisciplinary approach that combines qualitative and quantitative methods. The urban exposome framework was applied in a proof-of-concept study in Limassol, Cyprus combining: a mixed-methods study on stakeholders’ perceptions, a systematic assessment of secondary data from the cancer, birth and death registries, and a population health and biomonitoring survey. Data collection was conducted in summer 2017. The first results on drinking water and quality of life were described and combined with an agnostic environment-wide association analysis (EWAS). Water quality parameters and participants’ opinions on city life (i.e. neighborhood life, health care and green space access) were mapped using small administrative areas as the reference unit. In the exploratory EWAS analysis, all variables were used (questionnaire responses and water quality metrics) to describe correlations. Overall, urban drinking-water quality using chemical (disinfection byproducts-trihalomethanes) and microbial (coliforms, E. coli, and Enterococci) quality indicators did not raise concerns. General health and having a chronic disease were significantly (FDR-corrected p-value<0.1) associated with different health conditions e.g. hypertension and asthma, as well as having financial issues in access to dental care. Additionally, correlations between water trihalomethanes and participant behaviors (e.g. household cleaning, drinking water habits) were documented. This proof-of-concept study showed the potential of using integrative approaches to develop urban exposome profiles to prospectively identifying within-city differences in environmental and health indicators. The continuous monitoring of the urban exposome will allow stakeholders to timely identify and develop targeted to the city interventions to tackle urban health challenges.

A green alternative for degradation of trihalomethanes by nanocompounds and the use of bioassays to monitor genotoxic effects

Trihalomethanes (THMs) are undesirable contaminants that are generated during the pre-chlorination of water in water treatment stations which have been classified by international agencies as carcinogenic to humans. In this study, a green method for degradation of THMs in water via heterogeneous Fenton-like process catalyzed by cobalt-doped magnenite (Fe3-xCox4) was proposed. The determination of THMs degradation efficiencies by liquid-liquid extraction and gas chromatography–mass spectrometry revealed that under optimized conditions (THMs concentration of 240 μg L−1, pH 6, 400 mg of Fe3-xCox4 nanoparticles, and 400 μL of H2O2 (30%)), the proposed procedure was able to degrade THMs (trichloromethane (90%), bromodichloromethane (90%), bibromochloromethane (87%), and tribrommethane (86%)). The remain concentration of THMs were lower than value permitted in water intended for human consumption on Brazil (100 μg L−1). Genotoxicity, mutagenicity, and cytotoxicity tests were also carried out using the organic compounds under investigation, with the plant Allium cepa as a test subject. From the results obtained, it was concluded that the studied contaminants may present both genotoxic and mutagenic effects to exposed organisms. Through this study, it was possible to verify that the method developed has the potential to be used for environmental remediation.

Exposure to disinfection by-products in swimming pools and biomarkers of genotoxicity and respiratory damage – The PISCINA2 Study

BackgroundSwimming in pools is a healthy activity that entails exposure to disinfection by-products (DBPs), some of which are irritant and genotoxic. ObjectivesWe evaluated exposure to DBPs during swimming in a chlorinated pool and the association with short-term changes in genotoxicity and lung epithelium permeability biomarkers. MethodsNon-smoker adults (N = 116) swimming 40 min in an indoor pool were included. We measured a range of biomarkers before and at different times after swimming: trihalomethanes (THMs) in exhaled breath (5 min), trichloroacetic acid (TCAA) in urine (30 min), micronuclei in lymphocytes (1 h), serum club cell protein (CC16) (1 h), urine mutagenicity (2 h) and micronuclei in reticulocytes (4 days in a subset, N = 19). Several DBPs in water and trichloramine in air were measured, and physical activity was extensively assessed. We estimated interactions with polymorphisms in genes related to DBP metabolism. ResultsMedian level of chloroform, brominated and total THMs in water was 37.3, 9.5 and 48.5, μg/L, respectively, and trichloramine in air was 472.6 μg/m3. Median exhaled chloroform, brominated and total THMs increased after swimming by 10.9, 2.6 and 13.4, μg/m3, respectively. Creatinine-adjusted urinary TCAA increased by 3.1 μmol/mol. Micronuclei in lymphocytes and reticulocytes, urine mutagenicity and serum CC16 levels remained unchanged after swimming. Spearman correlation coefficients showed no association between DBP exposure and micronuclei in lymphocytes, urine mutagenicity and CC16. Moderate associations were observed for micronuclei in reticulocytes and DBP exposure. ConclusionsThe unchanged levels of the short-term effect biomarkers after swimming and null associations with personal estimates of exposure to DBPs suggest no measurable effect on genotoxicity in lymphocytes, urine mutagenicity and lung epithelium permeability at the observed exposure levels. The moderate associations with micronuclei in reticulocytes require cautious interpretation given the reduced sample size.