Concentrations Of Trihalomethanes Research Articles

The combination of multiple linear regression and adaptive neuro-fuzzy inference system can accurately predict trihalomethane levels in tap water with fewer water quality parameters

Artificial Neural Network (ANN) models are accurate in predicting the levels of disinfection by-products (DBPs) in drinking water. However, these models are not yet practical due to the large number of parameters involved, which should take a significant amount of time and cost to detect. Developing accurate and reliable prediction models of DBPs with fewest parameters is essential in the management of drinking water safety. This study used the adaptive neuro-fuzzy inference system (ANFIS) and radial basis function artificial neural network (RBF-ANN) to predict the levels of trihalomethanes (THMs), the most abundant DBPs in drinking water. Two water quality parameters identified by multiple linear regression (MLR) models were used as model inputs, and the quality of the models was assessed based on criteria such as correlation coefficient (r), mean absolute relative error (MARE), and the percentage of predictions with absolute relative error less than 25% (NE<25%) and over than 40% (NE>40%), etc. The results showed that the ANFIS models had higher correlation coefficients (r = 0.853–0.898) and prediction accuracy (NE<25% = 91%–94%) compared to RBF-ANN models (r = 0.553–0.819; NE<25% = 77%–86%) and traditional MLR models (r = 0.389–0.619; NE<25% = 67%–77%). Conversely, the prediction error, as indicated by MARE and NE>40%, showed the opposite trend: ANFIS models (MARE = 8%–11%; NE>40% = 0–5%) < RBF-ANN models (MARE = 15%–18%; NE>40% = 5%–11%) < MLR models (MARE = 19%–21%; NE>40% = 11%–17%). The present study provided a novel approach for constructing high-quality prediction models of THMs in water supply systems using only two parameters. This method holds promise as a viable alternative for monitoring THMs concentrations in tap water, thereby contributing to the improvement of water quality management strategies.

Comparison of Trihalomethane exposure assessment metrics in epidemiologic analyses of reproductive and developmental outcomes.

Researchers have developed exposure assessment metrics for disinfection by-products (DBPs) utilizing drinking water monitoring data and accounting for spatial and temporal variability, water consumption, and showering and bathing time with an expectation of decreasing exposure misclassification compared to the use of measured concentrations at public water supply (PWS) monitoring locations alone. We used exposure data collected for a previous study of DBPs to evaluate how different sources of information impact trihalomethane (THM) exposure estimates. We compared gestational exposure estimates to THMs based on water utility monitoring data alone, statistical imputation of daily concentrations to incorporate temporal variability, and personal water consumption and use (bathing and showering). We used Spearman correlation coefficients and ranked kappa statistics to compare exposure classifications. Exposure estimates based on measured or imputed daily THM concentrations, self-reported consumption, or bathing and showering differed substantially from estimates based solely on concentrations from PWS quarterly monitoring reports. Ranked exposure classifications, high to low quartiles or deciles, were generally consistent across each exposure metric (i.e., a subject with "high" exposure based on measured or imputed THM concentrations generally remained in the "high" category across exposure metrics.) The measured concentrations and imputed daily (i.e., spline regression) concentrations were highly correlated (r = 0.98). The weighted kappa statistics comparing exposure estimates using different exposure metrics ranged from 0.27 to 0.89, with the highest values for the ingestion + bathing/showering metrics compared to metrics for bathing/showering only (0.76 and 0.89). Bathing and showering contributed the most to "total" THM exposure estimates. We compare exposure metrics capturing temporal variability and multiple estimates of personal THM exposure with THM concentrations from PWS monitoring data. Our results show exposure estimates based on imputed daily concentrations accounting for temporal variability were very similar to the measured THM concentrations. We observed low agreement between imputed daily concentrations and ingestion-based estimates. Considering additional routes of exposure (e.g., inhalation and dermal) slightly increased agreement with the measured PWS exposure estimate in this population. Overall, the comparison of exposure assessment metrics allows researchers to understand the added value of additional data collection for future epidemiologic analyses of DBPs.

Occurrence and multi-pathway health risk assessment of trihalomethanes in drinking water of Wuxi, China

Chlorination is widely used to disinfect drinking water to keep humans safe from microorganisms. During chlorination, chlorine and its compounds react with contaminants to form disinfection by-products (DBPs). Toxicological and epidemiological studies have demonstrated that trihalomethanes (THMs) are the most widely investigated DBPs in drinking water, and their exposure has been associated with some adverse health effects. However, studies about risk characteristics in this field are limited. We estimated the health risks of THMs exposure in drinking water through multi-pathways, and systematically analyzed the factors influencing health risks of THMs in Wuxi, China. A total of 488 drinking water samples were collected and analyzed for THMs from four water treatment utilities from 2008 to 2016 in Wuxi. And water exposure parameters were obtained from 602 participants by structured questionnaires. The median concentration of THMs ranged from 6.71 μg/L to 9.18 μg/L. The cumulative cancer risk of THMs exposure through multi-pathways was 1.26 × 10−4, and CHBr2Cl made the largest contribution to the total cancer risk (48.25%). The non-cancer risk of THMs exposure was 2.02 × 10−1. Health risks of the exposure to THMs in drinking water in summer were significantly higher than that in winter (P = 0.0003 for cancer risk, and P = 5.95 × 10−7 for non-cancer risk). In our study, the average individual disability-adjusted life years (DALYs) lost was 1.27 × 10−4 per person-year (ppy). This study attempted to use DALYs for risk assessment of THMs, which will provide useful information for risk comparison and prioritization of hazards in drinking water. This suggested that potential higher risk might exist, and possible measures could be considered to decrease the health risks.

Combined application of EPANET and empirical model for possible formation of trihalomethanes in water distribution network of Chattogram city to identify potential carcinogenic health risk zone

The study identifies potential carcinogenic health risk-zone of Chattogram city for the occurrence of trihalomethanes (THMs) at its water distribution network. The EPANET-THMs simulation model along with an empirical model have been adopted in the study to predict THMs content of supply water of the distribution network of the city’s Karnaphuli service area. The empirical model has estimated THMs level of supply water based on influential water quality parameters, and few of these have been used as pre-set values for subsequent EPANET simulation. The simulation (R2= 0.7) shows that THMs’ concentrations throughout the network vary from 33 to 486 μg/L. Around 60% of total junctions showed THMs concentrations above 150 μg/L, while that is above 50 μg/L for most (99%) of the junctions. Residual Free chlorine, one of the precursors for the THMs formation in distribution line, has also been simulated by EPANET considering varying applied chlorine dose at the water purification unit and wall (Kw) and bulk (Kb) decay constants. The simulated free residual chlorine peaks are found to be closer to the actual values with chlorine dose of 2 mg/L, and decay constants, Kw = 1 d−1 and Kb = 1 d−1. A mean lifetime total risk of cancer due to the presence of THMs has been found to be very high. Spatial distribution of carcinogenic risk shows that the central zone of the service area is the most vulnerable zone, followed by the western and northern zone. The first ever zone wise risk identification could be used as baseline data for operational and regulatory purposes and may raise awareness among the city’s inhabitants. Furthermore, the application of EPANET in combination with an empirical model could be an effective tool for predicting THMs’ concentration in water distribution networks in developing countries like Bangladesh to minimize the expenses of measuring THMs.

Overlooked inorganic DBPs in trichloroisocyanuric acid (TCCA) disinfected indoor swimming pool: Evidences from concentration, cytotoxicity, and human health risk

Trichloroisocyanuric acid (TCCA) is a popular disinfectant for swimming pools in China. However, the occurrence and importance of regulated disinfection byproducts (DBPs) in TCCA-disinfected swimming pools are less understood. This study analyzed 12 regulated DBPs (4 trihalomethanes (THMs), 5 haloacetic acid (HAAs), bromate, chlorate, and chlorite) in 85 swimming pool water samples and 17 input tap water samples from one swimming pool for 17 days continuously. Considering water temperature, pH, free chlorine, total chlorine, and urea, most of swimming pool water samples were within the water quality limits for China. Total concentrations of THMs, HAAs, and inorganic DBPs of 20.4–42.2, 82.0–229, and 100–729 μg/L in the swimming pool, and 16.6–28.3, 8.2–12.8, and 64.4–95.6 μg/L in the tap water, indicating inorganic DBPs are the dominant swimming pool and drinking water pollutants. Cancer risk values of regulated DBPs in swimming pools and input tap water are 2.7E-05 and 8.1E-05, respectively, and exceed the US EPA's threshold (1.0E-06). The non-cancer risk is below the US EPA's threshold. Following TCCA disinfection, the concentration and calculated cytotoxicity of regulated DBPs had a 3.6-fold and 1.9-fold increase, respectively. Inorganic DBPs contribute to the calculated concentration and cancer risks of DBPs in swimming pools and tap water at sufficient concentrations warranting regulation. This study provides data on 12 regulated DBPs in TCCA-disinfected indoor swimming pools, highlighting the importance of inorganic DBPs from evidences of concentration, cytotoxicity, and cancer risk for the first time.

Comprehensive comparison of water quality risk and microbial ecology between new and old cast iron pipe distribution systems

The effects of cast iron pipe corrosion on water quality risk and microbial ecology in drinking water distribution systems (DWDSs) were investigated. It was found that trihalomethane (THMs) concentration and antibiotic resistance genes (ARGs) increased sharply in the old DWDSs. Under the same residual chlorine concentration conditions, the adenosine triphosphate concentration in the effluent of old DWDSs (Eff-old) was significantly higher than that in the effluent of new DWDSs. Moreover, stronger bioflocculation ability and weaker hydrophobicity coexisted in the extracellular polymeric substances of Eff-old, meanwhile, iron particles could be well inserted into the structure of the biofilms to enhance the mechanical strength and stability of the biofilms, hence enhancing the formation of THMs. Old DWDSs significantly influenced the microbial community of bulk water and triggered stronger microbial antioxidant systems response, resulting in higher ARGs abundance. Corroded cast iron pipes induced a unique interaction system of biofilms, chlorine, and corrosion products. Therefore, as the age of cast iron pipes increases, the fluctuation of water quality and microbial ecology should be paid more attention to maintain the safety of tap water.

Application of mathematical models for predicting the trihalomethanes content in drinking water in the city of Kumanova, North Macedonia

Trihalomethanes (THMs) are created as a result of the reaction between chlorine used to disinfect drinking water and natural organic matter in water. At high levels, THMs have been associated with cancer. As a consequence, THMs must be constantly monitored. They are mainly determined by the method of gas chromatography, which is a more difficult procedure and at a higher cost. In recent years, however, mathematical models have been used to predict THMs. These models work by measuring some physico-chemical parameters of drinking water, those values ​​of these parameters are replaced in mathematical models and the THMs content in drinking water can be predicted. The main purpose of this paper was to predict the content of THMs in the drinking water of the city of Kumanova. The measured parameters were: temperature, residual chlorine, pH, electrical conductivity, chemical oxygen, total dissolved solids and chlorides. Measurements were made during the spring season 2022 in the four sampling points. Ten mathematical models were used for prediction and of them the average value with standard deviation of THM was 26.9532 ± 10.03 μg/L. From the result we can conclude that content of THM does not pose a risk to the health of the population.

Effect of spray aeration on unregulated drinking water disinfection byproducts

AbstractSpray aeration is a comparatively low‐cost option to reduce trihalomethane (THM) concentrations in distribution system storage. The effect of spray aeration on unregulated, toxic disinfection by‐products was investigated in a bench‐scale apparatus in closed‐tank and open‐tank experiments. In the closed‐tank experiments, initially over 90% of THMs, trichloroacetonitrile, and chloropicrin were removed, while 36% of dihaloacetonitriles were removed. However, due to the buildup of concentrations in the tank headspace, removal rates for all compounds decreased significantly with time, falling to 44% removal of THMs, 76% removal of trichloroacetonitrile, and 58% removal of chloropicrin. Removal of dihaloacetonitriles decreased to zero. In the open‐tank experiments, THM removal rates were high and did not decrease with time. Considering the results with open and closed tanks as approximate bounds for performance expected under real‐world conditions in storage tanks, the findings suggest that spray aeration may not significantly reduce haloacetonitrile‐related toxicity while halonitromethane‐related toxicity may be reduced.

Trihalomethane Cancer Risk Assessment for Private and Shared Residences: Addressing the Differences in Inhalation Exposure.

The multi-pathway cancer risk (CR) assessment of trihalomethanes (THM) involves considering exposure via ingestion, dermal contact, and inhalation. Inhalation occurs during showering due to the volatilization of THMs from chlorinated water to the air. When assessing inhalation risks, exposure models commonly assume that the initial THM concentration in the shower room is zero. However, this assumption is only valid in private shower rooms where single or infrequent showering events take place. It fails to account for continuous or successive showering events in shared showering facilities. To address this issue, we incorporated the accumulation of THM in the shower room air. We studied a community (population ≈ 20,000) comprising two types of residences with the same water supply: population A with private shower rooms, and population B with communal shower stalls. The total THM concentration in the water was 30.22 ± 14.45 µg L-1. For population A, the total CR was 58.5 × 10-6, including an inhalation risk of 1.11 × 10-6. However, for population B, the accumulation of THM in the shower stall air resulted in increased inhalation risk. By the tenth showering event, the inhalation risk was 2.2 × 10-6, and the equivalent total CR was 59.64 × 10-6. We found that the CR significantly increased with increasing shower duration. Nevertheless, introducing a ventilation rate of 5 L s-1 in the shower stall reduced the inhalation CR from 1.2 × 10-6 to 7.9 × 10-7.

Variations of residual trihalomethane concentration in pipe-borne water during different in-house practices

Abstract This study was conducted to investigate the effect of different in-house practices on trihalomethane (THM) level fluctuations in pipe-borne water. Common in-house practices such as boiling, unboiling, boiling water with headspace/non-headspace, storage vessels materials, storage practices, and storage time were investigated to study residual THM and their percentage. Vessels made of plastic (P), clay (C), stainless steel (SS), glass (G), and aluminium (Al) were used for the study. Prime trihalomethanes of CHCl3, CHBrCl2, CHBr2Cl, CHBr3, and total of those four THMs (TTHMs) were measured, and removal/formation percentages were calculated. Results revealed that the percent change of TTHM varies based on the boiling practice as follows: open boiling TTHM &amp;gt; close boiling with headspace TTHM &amp;gt; close boiling without headspace (CBWH) TTHM. The following order was observed for residual TTHM for 6 h storage in the vessels; for CBWH water storage in open vessels C &amp;lt; G &amp;lt; P &amp;lt; SS &amp;lt; Al and close vessels C &amp;lt; G &amp;lt; P &amp;lt; SS &amp;lt; Al; and for unboiled water storage in open vessels SS &amp;lt; C &amp;lt; Al &amp;lt; P &amp;lt; G and close vessels C &amp;lt; P &amp;lt; Al &amp;lt; SS &amp;lt; G. In conclusion, the lowest concentration of residual TTHM was found in the boiled water stored in a clay pot and recommended as an in-house practice to reduce TTHM.

Predicting THM Formation and Revealing Its Contributors in Drinking Water Treatment Using Machine Learning

Trihalomethanes (THMs) are disinfection byproducts (DBPs) that are formed during chemical disinfection of drinking water. However, a variety of factors, including water qualities and treatment conditions, can influence THM formation, making it challenging to predict and highlight the underlying mechanisms. Here, we used machine learning (ML) algorithms to analyze the complex relations between influent characteristics and operational parameters to predict THM formation. Five ML algorithms were used to create predictive models for THM formation using five input parameters (i.e., chlorine dose/DOC, reaction time, pH, bromide concentration, and temperature). The least-squares boosting (LSBoost) model demonstrated its superiority in predicting THM concentrations on the training and test sets with both R2 values of 0.92. We also established a variant of the LSBoost model with an additional parameter, the specific ultraviolet absorbance (SUVA). Results showed that incorporating SUVA into model development gave a higher prediction accuracy on the training set with a reasonable R2 value of 0.97. The partial dependence plots (PDPs) and Shapley additive explanation (SHAP) models were employed for in-depth analysis to identify key drivers for THM formation. Our results showed that chlorine dose/DOC was the major driver for THM formation and SUVA had the least impact on THM formation.

Blood trihalomethane concentrations and allergic sensitization: A nationwide cross-sectional study

BackgroundExposure to disinfection by-products has been associated with several allergic diseases, but its association with allergen-specific immunoglobulin E (IgE) antibodies remains inconclusive. MethodsWe included 932 U.S. adolescents and 2187 adults from the National Health and Nutrition Examination Survey 2005–2006 who had quantified blood THM concentrations [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and 19 allergen-specific IgE antibodies. The odds ratios (ORs) of allergen-specific sensitization per 2.7-fold increment in blood THM concentrations were estimated by multivariable logistic regression models. ResultsBlood THM concentrations were unrelated to any allergen-specific sensitization in adults. Among adolescents, however, we found positive associations between blood TCM and chlorinated THMs (Cl-THMs: sum of TCM, BDCM, and DBCM) concentrations and the odds of pet sensitization [OR = 1.28 (95 % CI: 1.05, 1.55) and 1.38 (1.15, 1.65), respectively, per each 2.7-fold increment], between blood BDCM concentrations and the odds of mold [OR = 1.47 (1.24, 1.74)], plant [OR = 1.25 (1.09, 1.43)], pet [OR = 1.27 (1.07, 1.52)], and food sensitization [OR = 1.18 (1.03, 1.36)], and between blood brominated THM (Br-THMs: sum of BDCM, DBCM, and TBM) and total THM (TTHMs: sum of 4 THMs) concentrations and the odds of mold [OR = 1.52 (1.30 1.78) and 1.30 (1.03, 1.65), respectively], dust mite [OR = 1.39 (1.06, 1.82) and 1.45 (1.06, 1.98), respectively], and pet sensitization [OR = 1.42 (1.05, 1.92) and 1.54 (1.19, 1.98), respectively]. ConclusionHigher blood concentrations of THMs were associated with a greater risk of allergic sensitization among U.S. adolescents but not in adults.

New methods based on a genetic algorithm back propagation (GABP) neural network and general regression neural network (GRNN) for predicting the occurrence of trihalomethanes in tap water

Monitoring trihalomethanes (THMs) levels in water supply systems is of great significance in ensuring drinking water safety. However, THMs detection is a time-consuming task. Developing predictive THMs models using parameters that are easier to obtain is an alternative. To date, there is still no application of optimization algorithms and general regression neural networks in predicting disinfection by-products levels. This study was to explore the feasibility of back propagation neural network (BPNN), genetic algorithm back propagation (GABP) neural network and general regression neural network (GRNN) for predicting THMs occurrence in real water supply systems. The results showed that the BPNN models' prediction ability was limited (test rp = 0.571–0.857, N25 = 61.5 %–91.5 %). Optimized by the genetic algorithm (GA), GABP models were generated and exhibited better prediction performance (test rp = 0.573 and 0.696–0.863, N25 = 68.2 %–93.6 %). However, GABP models took a lot of time and their prediction performance was unstable. A GRNN was then used to generate simpler neural network models, and the resulting prediction performance was excellent (total trihalomethanes and bromodichloromethane: test rp = 0.657–0.824, N25 = 81.8 %–100 %). In general, GRNN was the best at predicting THMs concentrations among the three models. However, it is worth noting that the prediction accuracy of bromodichloromethane (BDCM) was not high, which may be due to the absence of key parameters affecting BDCM formation. Accurate predictions of THMs by GRNN with these nine water parameters made THMs monitoring in real water supply systems possible and practical.

Comparing risk of disinfection byproducts in drinking water under variable scenarios of seawater intrusion

The higher levels of halides in seawater increase bromide and iodide in the coastal aquifers, leading to higher concentrations of halogenated disinfection byproducts (DBPs). The populations in the coastal areas are susceptible to increased concentrations of DBPs while many DBPs are cyto- and genotoxic to mammalian cells, and are possible/probable human carcinogens. The implications of seawater intrusion on the concentrations of trihalomethanes (THMs) and haloacetic acids (HAAs), and the risks were analyzed by adding 0.0–2.0 % seawater (SW) (by volume) and chlorine to groundwater. Bromide and iodide concentrations in groundwater (0.0 %SW) were observed as 42.5 and non-detected (ND) μg/L respectively. With 2.0 %SW, these were spiked up to 1100 and 2.1 μg/L respectively. The most common THMs (THM4), iodinated THMs (I-THMs) and HAAs were 30.4, 0.13 and 27.9 μg/L for 0.0 % SW respectively. With 2.0 %SW, these values were 106.3, 1.6 and 72.9 μg/L, respectively. At 0.0 %SW, averages of chronic daily intakes (CDI) for THM4, HAAs and I-THMs were 2.61 × 10−4, 2.26 × 10−4 and 7.69 × 10−7 mg/kg/day respectively, which were increased to 9.97 × 10−4, 4.70 × 10−4 and 9.47 × 10−6 mg/kg/day, respectively for 2.0 %SW. For 0.0 %SW, overall cancer risks from few DBPs was 3.09 × 10−5 (6.46 × 10−6 - 7.23 × 10−5) while at 1.0 % and 2.0 %SW, risks were 4.88 × 10−5 (1.26 × 10−5–1.08 × 10−4) and 4.11 × 10−5 (1.21 × 10−5–9.28 × 10−5) respectively. The reduction of risks for 2.0 %SW was due to the increase of bromoform (TBM), and decrease in bromodichloromethane (BDCM) and dibromochloromethane (DBCM) at 2.0 %SW. The disability-adjusted life years (DALY) loss showed an increasing trend from 0.0 %SW (DALY: 77.30) to 1.0 %SW (DALY: 122.0) while an increase to 2.0 %SW showed a decrease in DALY (DALY: 102.8). Future study on toxicity of other regulated and emerging DBPs is warranted to better predict cancer risks.

HS-SPME-GC/MS Method for the Simultaneous Determination of Trihalomethanes, Geosmin, and 2-Methylisoborneol in Water Samples

Drinking water treatment plants (DWTP) use chlorination as an oxidation stage in the first step of the processes used to eliminate the natural organic matter (NOM) responsible for the formation of 2-methylisoborneol (2-MIB) and Geosmin (GM), which produce odor and taste to the water. However, chlorination processes give rise to disinfectant toxic subproducts, such as trihalomethanes (THMs). In this work, a headspace solid-phase microextraction coupled with a gas chromatography/mass spectrometric method has been developed for the quality control of drinking water. 2-MIB, GM, and THMs at different stages of the drinking water treatment process were monitored. The method was validated following the Environmental Protection Agency guidelines. Neither carryover nor the matrix effect was observed. The performance of the method was satisfactory in terms of selectivity, repeatability, and accuracy and exhibited a linear concentration range of 0.8–50 µg/L for trichloromethane (TCM), 0.05–20 µg/L for bromodichloromethane, 0.01–20 µg/L for dibromochloromethane and tribromomethane, and 0.005–0.05 µg/L for GM and 2-MIB. The THMs concentration obtained for all the water samples was below the thresholds established by international organizations and, for 2-MIB and GM, were lower for their limit of quantification. The method was also applied to the adsorption kinetic study of TCM on granulated activated carbon, which is the main barrier to reducing the NOM in DWTP.

Urinary trihalomethane concentrations and liver function indicators: a cross-sectional study in China.

While it is known that exposure to disinfection by-products (DBPs), including trihalomethanes (THMs), impairs liver function, few epidemiological studies have explored this association. Here, we determined the concentrations of four urinary trihalomethanes (chloroform [TCM], and three Br-THMs, bromodichloromethane [BDCM], dibromochloromethane [DBCM], and bromoform [TBM]), and nine serum liver function indicators in 182 adults ≥ 18years of age, examined at a medical examination center in Wuxi, China, in 2020 and 2021. Generalized linear model analysis revealed positive associations between urinary DBCM and alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), total protein (TP), and albumin (ALB). Urinary Br-THMs and total THMs (TTHMs) were positively associated with ALT, AST, TBIL, indirect bilirubin (IBIL), TP, and ALB (all P < 0.05). Urinary THMs were not associated with alkaline phosphatase (ALP) or glutamine transaminase (GGT) (all P > 0.05). Generalized additive model-based penalized regression splines were used to confirm these associations. In conclusion, THM exposure was associated with altered serum biomarkers of liver function.

Investigation of the correlation between trihalomethane concentrations and socioeconomic factors in NY State

Recent environmental justice studies have found associations between low drinking water quality and socioeconomic indicators such as income and race. Trihalomethanes, probable human carcinogens, are commonly found disinfection by-products (DBPs) in public water systems (PWS). Although trihalomethanes are correlated with socioeconomic indicators, there is a knowledge gap regarding how the level of contaminants correlates with socioeconomic indicators and other physicochemical factors in specific regions. Therefore, we investigated the correlation between trihalomethane concentrations and socioeconomic factors in New York State with more practical and insightful data analysis and interpretation compared to those in previous studies by providing more detailed city-level data and water system characteristics affecting the correlation. We found a negative correlation between median household income and trihalomethane concentrations in the state. The communities served by PWS using groundwater sources had lower trihalomethane concentrations and higher household income, suggesting that water quality parameters contribute to the negative correlation between trihalomethanes and income levels. The inverse association between trihalomethanes and household income may indicate socioeconomic disparity regarding drinking water quality and the need for improved efforts to assist small- and medium-sized community water systems to lower DBP levels in New York State because small- or medium-sized systems may have fewer resources to apply DBP control and removal technologies compared to large systems.

Exposure and carcinogenic risk assessment of trihalomethanes (THMs) for water supply consumers in Addis Ababa, Ethiopia.

Trihalomethanes (THMs), a class of DBPs (disinfection byproducts) that includes chloroform, bromodichloromethane (BDCM), chlorodibromomethane (CDBM), and bromoform. To the best of authors' knowledge, no study has addressed the relationship between the concentration of THMs and lifetime cancer risks (LCR) in drinking water supply system in Addis Ababa, Ethiopia. Therefore, this study aimed to determine the lifetime cancer risks of exposure to THMs in Addis Ababa, Ethiopia. A total of 120 duplicate water samples were collected from 21 sampling points in Addis Ababa, Ethiopia. The THMs were separated by a DB-5 capillary column and detected by an electron capture detector (ECD). Cancer and non-cancer risk assessments were performed. The average total THMs (TTHMs)concentration in Addis Ababa, Ethiopia, was 76.3μg/L. Chloroform was the most dominant THM species identified. The total cancer risk for males was higher than that for females. The average LCR for TTHMs via ingestion in drinking water in this study was unacceptably high risk . An average LCR through dermal routes was also of unacceptably high risk . The LCR by chloroform contributes the highest (72%) of the total risk, followed by BDCM (14%), DBCM (10%) and bromoform (4%). The cancer risk of drinking water due to THMs in Addis Ababa was higher than the level recommended by the USEPA. The total LCR from the targeted THMs was higher via the three exposure routes. Males were at higher THM cancer risk than females. The hazard index (HI) indicated that the dermal route caused higher HI values than the ingestion route. It is essential to apply alternatives to chlorine, i.e., chlorine dioxide (ClO2), ozone and ultraviolet radiation, in Addis Ababa, Ethiopia. The monitoring and regulation of the THMs is required on a regular basis to analyse the trends and guide the water treatment and distribution system. The datasets generated for this analysis are available from the corresponding author upon reasonable request.

Application of Mathematical Models for Predicting the Trihalomethanes Content in Drinking Water in the City of Struga, North Macedonia

Application of Mathematical Models for Predicting the Trihalomethanes Content in Drinking Water in the City of Struga, North Macedonia

Evaluation of trihalomethane concentration in drinking water

تناولت هذه الدراسة مشكلة تكّون المركبات الجانبية نتيجة لتفاعل المواد العضوية الطبيعية مع الكلور المستخدم للتعقيم حيث تسبب هذه المركبات وحسب البحوث والدراسات المكثفة العديدة من الامراض السرطانية. لذا كان من الضروري اجراء تقييم لوجود هذه المركبات في مياه الشرب وبالتحديد لمدينة بغداد. فقد عملنا تقييم على مدى (7) اشهر ابتداءا" من (نيسان ولغاية تشرين الاول) ولاحظنا وجود عدة مناطق لديها تركيز مادة الكلوروفوم والذي هو احد مجموعة التراي هالوميثان والمركب الاول في المجموعة عالي وفوق الى المسموح به. وتناولنا طريقتي معالجة للحد من تكّون هذه المركبات وهي استعمال (الكاربون المنشط) وتقنية (التخثير المحسن) حيث اوضحت النتائج مدى فعالية هذه الطرق وكفاءتها وكذلك تناولنا نوعين من المخثرات في تقنية التخثير المحسن كبدائل عن الشب الذي هو شائع الاستخدام في محطاتنا وهي مركبات الحديد والمواد البوليمرية مثل البولي المنيوم كلورايد(PACL).