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Characteristics of trihalomethane (THM) production and associated health risk assessment in swimming pool waters treated with different disinfection methods
... The main oxidants were HClO and ClO − , while other oxidants included ozone, hydrogen peroxide, and chlorine dioxide [54]. The earliest study on EGMO was reported in 2009, and there were about 10 papers, which reported the EGMO disinfection in swimming pools [83]. ...
... Since the data in this study come from different research papers, in which the water samples, sampling methods, and treatment methods were not totally consistent, the uncertainties may be occurred for comparing the concentrations of DBPs from different disinfection techniques. Noting: a Data were collected from [3,4,7,10,15,28,29,34,11,34,83,50,52,62,72,104,109,52]. b We did not find detailed individual data on ClO 2 , so we used the category DBPs concentrations instead. ...
... Data were collected from [52,73]. c Data were collected from [111,61,29,11,50,83]. d Data were collected from [28,61,15]. ...
Swimming pools is a significant exposure scenario of disinfection byproducts (DBPs) owning to its much higher DBPs concentration compared to drinking water. Although many reviews regarding occurrence, formation and impacts of swimming pools DBPs have been published, a comprehensive reviewer regarding the influence of techniques on DBP formation and cytotoxicity/genotoxicity in swimming pools is lacking. In this
review, the occurrences of highly toxic emerging DBPs as well as their formation and cytotoxicity/genotoxicity in different disinfection techniques were analyzed. For emerging aliphatic DBPs, the average concentrations of haloaldehydes (HALs), haloamides (HAMs), haloacetonitriles (HANs), haloketones (HKs), and halonitromethane (HNMs) in global swimming pools were 255, 290, 23.8, 31.6, and 6.0 μg/L, which are about 3–5 times higher
than these in global drinking water. The average formation potentials of 9 classes of aliphatic DBPs in chlorine, UV/chlorine, ozone/chlorine, copper-silver ion (CSI)/chlorine, electrochemically generated mixed oxidant (EGMO), ClO2, and trichloroisocyanuric acid (TCCA) were 645, 897, 470, 546, 1306, 85.4, and 195 μg/L,
respectively. ClO2 and TCCA showed good performance on the control of organic DBPs, while they caused the formation of other DBPs e.g., chlorate, chlorite, and cyanuric acid. Combined advanced oxidation processes with emerging disinfects may be a good way to control the aliphatic DBPs in swimming pools. This is the first attempt to highlight the occurrence of emerging DBPs in swimming pools as well as their formation potential and toxicity in different disinfection techniques, which can help swimming controller to select the best disinfection technique for DBP elimination.
... These concentrations were similar to THMs in a Beijing swimming pool's water reported by Wang and Dong (2020) and several Shanghai indoor pools' water reported by Shi et al. (2020). The results from our study were higher than the results from (Zhang et al. 2015) and chlorinated swimming pool waters in Seoul (Korea) (Lee et al. 2009). According to the standard GB37488-2019 (NHC 2019), the content of THMs in swimming pool water should be less than 200 μg/L, and the indoor swimming pool in this study met this standard during all sampling times. ...
... TCM made up the largest proportion of THMs, followed by BDCM and DBCM, and finally TBM (Fig. 2a), which agreed with other studies (Lee et al. 2009;Shi et al. 2020;Manasfi et al. 2016;Yeh et al. 2014;Bessonneau et al. 2011). The average proportion of TCM in THMs was 62.2, 54.2, 50.2, and 49.8% at the four sampling times, suggesting the proportion of TCM decreased with time while the proportion of BDCM and DBCM increased with time. ...
... The total LCRs of THMs via three routes ranged from 1.368 × 10 −5 to 1.968 × 10 −5 . The average LCR of THMs in this study was slightly lower than what was reported in Taiwan (6.87 × 10 −5 and 5.46 × 10 −5 ) (Chen et al. 2011), Thailand (7.53 × 10 −4 ) (Panyakapo et al. 2008), Shanghai (3.83 × 10 −4 ) (Shi et al. 2020), and Korea (7.77 × 10 −4 -1.36 × 10 −3 ) (Lee et al. 2009). The risk values in this study were at an acceptable risk level (10 −4 to 10 −6 ), but the cancer risks from THMs exposure in this swimming pool is still of concern. ...
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 0.038–0.118 μg/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.
... Various researchers had carried out studies to assess the THM concentrations in different types of waters (Budziak and Carasek 2007;Pavón et al. 2008;Al-Omari et al. 2005). THMs in indoor swimming pool water has reported in various countries like United States, Spain, Korea, UK, Italy, Germany, Thailand, Poland, Taiwan, and Iran (Amer Kanan 2010; Santa Marina et al. 2009;Lee et al. 2009;Chu & Nieuwenhuijsen 2002;Fantuzzi et al. 2001;Erdinger et al. 2004;Panyakapo et al. 2008;Hsu et al. 2009;Kozłowska et al. 2006;Heydari et al. 2013). In most of the studies, pool water uses Cl 2 as the disinfectant. ...
... The study on carcinogenic and non-carcinogenic effects of THMs in swimming pools is essential in public health. Few studies reported higher health risk using different measurements and indicators such as lifetime cancer risk, Hazard Index (HI), genotoxic risk, etc. (Tokmak et al. 2004;Lee et al. 2009;Jesonkova and Bozek 2013;Peng et al. 2020;Felgueiras et al. 2020). A study was reported that THMs levels in post showered blood samples were highly correlated with CF in water and air by inhalation (Silva et al. 2012). ...
... LCR was mainly from exposure to CF by inhalation found to be higher than 10 -6 in all the pools for both male and female swimmers. In contrast, exposure to the other components of THMs by ingestion and dermal observes to be negligible (Lee et al. 2009). From the LCR Inh calculations in the pool-2 swimmers will be impacted by all components of THM on continuous exposure, while pool-3 and 8 swimmers will be affected by CF and DBCM and similarly pool-7 by CF and BF. ...
Tri halo methanes (THMs), a common disinfection by products in swimming pool water are the major concern in Kuwait. With the objective of assuring the safety and health of the swimmers, the study was focused on THMs in indoor pool samples collected from mid-July to October 2018. pH, temperature, residual chlorine, and total organic carbon were analyzed in relation to THMs. The concentration ranged from 1.9 to 85.7 µg/L in all pools, and the values were within the specification limits on an average for each pool. A few significant correlations were established between Tri halo methane components from statistical analysis. Since long-term exposure of Tri halo methanes affect swimmer's health, the total lifetime cancer risk index was calculated and observed that all the pools had a value greater than 10–6, including both male and female swimmers. The main contribution of risk identified from the study was chloroform exposure through inhalation. Also, the non-carcinogenic effect on swimmers using hazard index was estimated and determined that few pools exceeded the value1.0. The average total lifetime cancer risk of all pools for men and women (8.03 × 10−6 and 8.8 × 10−6 ), hazard index for men and women (1.31 and 1.43) were above guidelines and classified as risk. Therefore, the pools should be monitored and maintained with care to reduce the concentration of disinfectant used and subsequently lowers the generation of THMs. The frequent cleaning of pools will help to continue swimming without any long term exposure effects.
... This study aimed to determine the concentration of chloroform as an indicator of THMs in the swimming pool of Shiraz University of Medical Sciences and estimate human health risk for the swimmers. The previous studies revealed high concentrations of THMs in swimming pools, with chloroform (CHCl 3 ) being the predominant species (Lee et al., 2009;Erdinger et al., 2004;Weaver et al., 2009;Simard et al., 2013). ...
... This might be associated with the simultaneous use of chlorination and ozonation for disinfecting the pool. Lee and Blahley (Lee et al., 2009) also reported that the chloroform concentration ranged from 70 to 140 μg/l in three chlorinated pools based on a small data set (Li and Blatchley, 2007). ...
... The value of which was equals 35.93μ which is a small amount and won't cause a significant problem through exposure to chloroform. A study by Lee et al. (2009); Which was performed to estimate exposure to trihalomethanes indoors in a swimming pool, showed that the highest exposure was through inhalation. While risks from dermal exposure and oral ingestion to THMs were the negligible risk level defined by the USEPA (<1μ) (Lee et al., 2009). ...
This cross-sectional study aimed to examine the concentration of the by-products of chlorination in the swimming pool and estimate human health risk for the swimmers of Shiraz University of Medical Sciences. In this study, the chloroform concentrations of 16 samples were measured using Gas Chromatography (GC). All the measured concentrations were less than the allowed amount announced by the World Health Organization (WHO). The results of the cancer risk (CR) and hazard index (HI) showed that the major exposure routes were found to be dermal during swimming and the 95 percentile of estimated CR and HI for the male group were 1.38 × 10⁻¹⁰ and 1.82 × 10⁻⁵ respectively, which is higher than the values of 5.48 × 10⁻¹⁰ and 2.25 × 10⁻⁵ respectively, for the women group. Sensitivity analyses indicated that the swimming exposure time (ET), and chloroform concentration were the most relevant variables in the health risk model. Therefore, knowledge about the sources of micro-pollutants in swimming pools might help promote the health methods of the pool environment.
... The study of DBPs' in water took the interest of the researchers for their carcinogenicity and adverse health effects. [1,[8][9][10][11]. Various classes of DBPs' compounds include: Trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs) and haloketones (HKs). ...
... DBPs in drinking water have positive association with cancer and potential adverse reproductive effects. Numerous studies found that DBPs that have been associated with several adverse health effects from long-term exposure, including bladder and colorectal cancer and adverse birth outcomes [8][9][10]16]. Few studies have been investigated the relationship between chlorination of drinking water and cancer mortality through toxicological laboratory studies [19][20][21][22]. ...
... Few studies have been investigated the relationship between chlorination of drinking water and cancer mortality through toxicological laboratory studies [19][20][21][22]. A linkage between exposure to chlorinated drinking water and the development of urinary bladder cancer is detected [9,10,21]. Moreover, kidney, liver and intestinal tumorigenesis are also found to be associated with chronic ingestion of THMs [22,23]. ...
This study predicts the possible occurrence of trihalomethanes (THMs) in water supply of Chattrogram city in Bangladesh, and life time cancer risk from multi-pathway intakes of the trihalomethanes (THMs) to the city dwellers. A total of 11 water samples were collected from the distribution network of the city, and few water quality parameters were analyzed in the study. Three empirical models developed by Amy et al. (1998), Rathbun (1996), and Malcolm Pirnie (1993) were used to estimate the level of THMs from measured water quality data, and were denoted as MODEL1, MODEL2 and MODEL3, respectively in the study. Lifetime cancer risk was estimated using predicted chronic daily intakes (CDI) of THMs' species for different exposure routes (ingestion, inhalation and dermal). The total concentrations of THMs ranged between 20 and 440 μg/L, 95–215 μg/L and 162–249 μg/L were predicted by MODEL1, MODEL2 and MODEL3, respectively. An average lifetime cancer risk was predicted as 1.4 × 10⁻⁴, 1.1 × 10⁻⁴ and 2.9 × 10⁻⁴ for oral, inhalation and dermal exposure, respectively from the water supply of the city. Percent contribution to total lifetime cancer risk were predicted as 50, 40 and10 for oral ingestion, inhalation and dermal absorption, respectively. The study revealed that lifetime cancer risk values were higher than minimum risk level set by United States Environmental Protection Agency. The findings of possible occurrence of THMs in the water supply and associated cancer risk might be beneficial as baseline data for further investigation, and help the decision makers regarding the formulation of standards and legislations of THMs.
... En relación a la práctica de la natación, uno de los elementos de mayor controversia en la comunidad científica durante la última década es el relativo al tratamiento químico del agua utilizado en este tipo de instalaciones, que en la actualidad y principalmente debido a su reducido coste continúa siendo mayoritariamente basado en el cloro y sus derivados, a pesar de que se ha observado que este tipo de mantenimiento se asocia a determinados problemas de salud (Lee, Ha & Zoh, 2009), así como es susceptible de provocar accidentes en piscinas por la gene-ración de cloro gas (Agabiti et al., 2001; Almagro, Acuña, Hernández & Robles, 2009). Por ello, a raíz de numerosas investigaciones la teoría denominada «the chlorine hypothesis», nacida en Bélgica, sostiene que los subproductos de desinfección de piscinas cubiertas tienen un importante papel en el desarrollo del asma, alergias y otras enfermedades pulmonares en niños y adultos en Europa (Bernard et al., 2003;Bernard, Carbonelle, Dumont & Nickmilder, 2007;. ...
... No obstante, algunos autores mantienen que pueden generar los mismos problemas de salud y mantenimiento que el cloro (Medina & Jiménez-Valenzuela, 2011). Del mismo modo, existen otros tratamientos complementarios a los anteriores que utilizan el ozono, la radiación ultravioleta y la ionización cobre-plata y que permiten mejorar la calidad del agua, puesto que están considerados más desinfectantes y que al mismo tiempo reducen la cantidad de producto químico necesaria para el tratamiento (Cassan, Mercier, Castex & Rambaud, 2006;Corominas et al., 2009;Gomà, 2001;Lee et al., 2009). Más aún, recientemente han sido publicados distintitos documentos de consenso en los que además de comparar los diferentes métodos de desinfección, se indican las diferentes recomendaciones para minimizar los problemas a través de una mejora en la ventilación de la lámina de agua y el estricto control de los parámetros establecidos por normativa sin necesidad de incluir estos tratamientos de alto coste (Corominas et al., 2009;Fernández-Luna et al., 2011;Santa-Marina et al., 2009). ...
... Para ello, se utilizan determinados productos químicos cuya concentración debe estar limitada para que a su vez no genere otro tipo de riesgos en las personas. Tradicionalmente la sustancia a nivel mundial más utilizada para llevar a cabo estas funciones ha sido el cloro, seguido del bromo y en menor medida el peróxido de hidrógeno (Lee et al., 2009). La mayor parte de los trabajos que se han llevado a cabo hasta la fecha respecto a los tratamientos químicos en piscinas cubiertas se han dirigido a la búsqueda e identificación de los compuestos químicos nocivos para la salud que se pueden encontrar en el agua y en el aire dentro de estas instalaciones. ...
El objetivo de este trabajo fue identificar los tratamientos químicos del agua utilizados en piscinas cubiertas y los métodos para evaluar sus efectos en la función y aparato respiratorio de diferentes poblaciones asistentes a estas instalaciones. Se realizó una búsqueda de publicaciones científicas y libros sobre los tratamientos químicos en piscinas y sus efectos en la salud y la función respiratoria. Los tratamientos químicos en piscina basados en el cloro y el bromo generan subproductos de desinfección dañinos para el organismo (DBPs) como las cloraminas y los trihalomentanos (THM). Existen tratamientos alternativos como ultravioleta y ozono que reducen la formación de DBPs. Los métodos de evaluación utilizados para detectar enfermedades, daño pulmonar y de las vías respiratorias son las técnicas basadas en la espirometría, y el análisis de biomarcadores en plasma o suero sanguíneo (proteínas CC16, surfactantes A, B y D, Inmunoglobulina específica), aire exhalado (óxido nítrico, citoquinas), orina (CC16, leukotrieno B4), esputo o saliva (eosinofilos y linfocitos) y DBPs en aire exhalado, sangre u orina. Los efectos observados en las diferentes poblaciones han sido el aumento de la permeabilidad del epitelio pulmonar, la inflamación de las vías respiratorias y síntomas asociados al asma, hiper-reactividad bronquial y rinitis alérgica. Los efectos negativos detectados en el aparato respiratorio de las diferentes poblaciones en piscinas están relacionados con la exposición a productos químicos. Algunos Biomarcadores (como la proteína CC16) obtienen una mayor fiabilidad. Los tratamientos complementarios (ozono y ultravioleta) no han sido evaluados y pueden suponer una reducción en los problemas respiratorios de nadadores y trabajadores.Palabras Clave: biomarcadores, enfermedades respiratorias, espirometría, natación, subproductos de desinfección.Abstrac: The aim of this study was to identify the effects on respiratory function produced by water chemical treatments in the indoor pools in different populations. We made a review of the scientific literature about chemical treatments of water and assessment methods used to detect health effects and respiratory function. Chemical treatments chlorine and bromine generate disinfection byproducts (DBPs) that are harmful to the body, such as chloramines and trihalomethanes (THM). There exist alternative treatments such as ultraviolet radiation and ozone to reduce the formation of DBPs. The methods used to detect diseases of the respiratory tract are spirometry, analysis of biomarkers in plasma or serum (CC16 proteins, surfactants A, B and D, etc..) and exhaled air (nitric oxide, cytokines). The health problems that have been observed are the increase in lung epithelial permeability, inflammation of the airways and other symptoms associated with asthma, allergic rhinitis and bronchial hyper reactivity. The negative effects on respiratory function are related to prolonged exposure to chemicals (chlorine and bromine) in indoor swimming pools. Some biomarkers such as protein CC16 obtain greater reliability as a measurable variable. The reduced presence of DBPs in combination water treatments may be a way to reduce respiratory problems. However, more research is needed for confirmation.Key words: biomarkers, disinfection by products, lung diseases, spirometry, swimming.
... Temperature ranged from 31°C to 33.4°C. Both these values fall under the prescribed WHO guideline limits [62], and are similar to those reported in other research investigations [34,39,45]. Residual chlorine content of the samples varied from 0.0703 to 0.1418 Cl 2 mL −1 , which appeared to be quite low to achieve proper disinfection of swimming pool water. ...
... High level of observed THMs may be attributed to the presence of high level of NOM content in pool water [37]. A comparative study revealed that observed THMs levels were higher than those reported in countries like Korea [34], Italy [2], UK [15], Canada [45], Germany [33] and Spain [9]. As mentioned above, Henry's law was used to estimate the concentration of THMs in air. ...
... Inhalation exposure risk values were approximately three times higher than the acceptable risk level (10 −6 ) thus indicating significant risk and possible concerns on human health. Previous studies also reported inhalation to be the major route of exposure [18,34]. Few studies, though, suggest dermal exposure to be the most significant pathway [13]. ...
Disinfection is an important process to make the water free from harmful pathogenic substances, but sometimes it results in the
formation of harmful by-products. Development of predictive models is required to define the concentration of THMs in pool
water. Majority of studies reported inhalation to be the most significant THMs exposure route which is more likely to be
dependent upon the concentration of THMs in pool water and in air. THMs concentration in the analyzed pool water samples
and in air was found to be 197.18 ± 16.31 μg L−1 and 0.033 μgm3–1, respectively. Statistical parameters such as high correlation
coefficients, high R2 values, low standard error, and low mean square error of prediction indicated the validity of MLR based
linear model over non-linear model. Therefore, linear model can be most suitably used to pre-assess and predict the THMs levels
in swimming pool water. Risk estimation studies was conducted by using the united states environmental protection agency
(USEPA) Swimmer Exposure Assessment Model (SWIMODEL). The lifetime time cancer risk values related to chloroform
exceeded 10−6 for both the sub-population. Inhalation exposure leads to maximum risk and contributed up to 99% to total cancer
risk. Risk due to other exposure pathways like accidental ingestion and skin contact was found to be negligible and insignificant.
Monte Carlo simulation results revealed that the simulated THMs risk values for the studied exposure pathways lies within
±3.1% of the average risk values obtained using SWIMODEL. Hence, the risk estimates obtained using SWIMODEL seemed to
be appropriate in determining the potential risk exposure of THMs on human health. Variation in input parameters like body
weight (BW) and skin surface area (SA) leads to difference in risk estimates for the studied population. Non cancer riskwas found
to be insignificant as represented by low hazard quotient (HQ < 1) values. Through monitoring and regulations on control of
THMs in swimming pool water is required to minimize the risk associated.
... Pool water treatment also plays a factor and affects air and water quality [19]. Some research focused on changes in the water treatment system by introducing modifications such as a column with the activated carbon or with an ion-exchange deposit; this research indicated that the exchange of water led to a decrease of DBP concentrations [24][25][26][27]. ...
... Through accumulation in the cells of living organisms, they have carcinogenic, mutagenic, and teratogenic effects. These compounds can cause: asthma [24,[31][32][33], upper respiratory problems [32,34,35], eye and skin irritation [6,32], cancer [36], including bladder cancer [37][38][39], and even infertility [40,41]. ...
... Due to this, a straightforward and economical solution to help combat increased DBP concentrations was sought. Reducing DBP levels in pool water include introducing changes in the water treatment system [19,24,26,27]. The positive impact of the total pool water exchange is also indicated, thanks to which the impurities accumulated in the water are removed [27]. ...
Pool water must be constantly disinfected. Chlorine compounds used to disinfect pools react with organic substances such as sweat, urine, and personal care products introduced into pool water by users and results in the formation of disinfection byproducts. Trihalomethanes (THM), including chloroform and dissolved organic carbon (DOC) concentrations, were quantified using a two-stage process: determining initial THM and chloroform levels; then searching for a cheap and easy-to-use method to improve water quality. The method proposed here to limit THM and DOC concentrations in water is controlled showering. At three swimming pool facilities, chloroform concentrations (13.8 ± 0.33 µg/L, 15.5 ± 0.44 µg/L, and 13.9 ± 0.06 µg/L) were below the threshold concentration of 30 µg/L. At a fourth facility, however, the chloroform concentration exceeded that threshold (40.7 ± 9.68 µg/L) when showering was not controlled. Those conditions improved after the introduction of a mandatory shower; concentrations of DOC, THMs, and chloroform all decreased. The chloroform concentration decreased to 29.4 ± 3.8 µg/L, the THM concentration was 31.3 ± 3.9 µg/L, and the DOC concentration was 6.09 ± 0.05 mg/L. Pilot tests were carried out at real facilities to determine whether the control of pre-swim hygiene was possible. The introduction of proper pre-swim hygiene limited the concentration of DOC in water and can lead to a healthier environment for everyone attending the swimming facility.
... Unfortunately, disinfectants can react with many components (e.g., natural organic matter, bromide, and iodide), thereby resulting in the formation of disinfection byproducts (DBPs) (Chowdhury et al., 2014;Ersan et al., 2019;Hang et al., 2016;Yang et al., 2016). Toxicological studies have revealed that many DBPs are carcinogenic and teratogenic, and epidemiological studies have shown that several health issues are associated with exposure to DBPs, such as reproductive health effects, asthma, and bladder cancer (Carter and Joll, 2017;Chen et al., 2011;Font-Ribera et al., 2016;Lee et al., 2009). In a recent study, Font-Ribera et al. (2019) reported moderate associations with micronuclei in reticulocytes and DBP exposure while swimming in a chlorinated pool. ...
... The risk posed by DBPs in swimming pools have been revealed by previous studies (Gouveia et al., 2019;Yang et al., 2018a;Hang et al., 2016;Chowdhury, 2015;Chen et al., 2011;Lee et al., 2009;Panyakapo et al., 2008). Panyakapo et al. (2008) calculated the cancer risks from the highest and average concentrations of THMs in swimming pools in Thailand (1.38 × 10 −3 and 7.53 × 10 −4 , respectively). ...
... For women, the mean total risk was slightly higher than that for men owing to the differences in skin surface area and body weight. In indoor swimming pools, inhalation risks of THMs provided a higher contribution to the total cancer risk, which was consistent with the conclusions reported by other published articles (Gouveia et al., 2019;Hang et al., 2016;Chen et al., 2011;Lee et al., 2009). Lee et al. (2009) found that the lifetime cancer risks posed by THMs from oral ingestion and dermal exposure are mostly less than 10 −6 , and swimmers are at a higher risk of inhalation exposure (7.77 × 10 −4 -1.36 × 10 −3 ). ...
Disinfection is an indispensable water treatment process used to inactivate pathogens and prevent outbreaks of infectious diseases in swimming pools. However, toxic disinfection byproducts (DBPs) are inevitably formed during the process. To improve the supervision and regulation of DBPs in swimming pools, the reliability of using trihalomethanes (THMs) as the sole indicator of organic DBPs and the possibility of using easily detectable water quality parameters as predictors of DBPs were discussed based on the occurrence of 29 typical DBPs in swimming pools. Among the target DBP categories, THMs and haloacetic acids (HAAs) were the prominent species, and the concentrations of HAAs were the highest. The risk assessment results indicated that the total risk values in most pools were higher than the acceptable value (10⁻⁶). Compared with nitrosamines and THMs, HAAs were the main contributors to the cancer risks posed by dermal absorption and ingestion. THMs (r = 0.619; p < 0.01) and HAAs (r = 0.989; p < 0.01) were both significantly correlated with total DBPs (the sum of 29 DBPs). A stepwise multivariate regression model was developed by analyzing the correlations between total DBPs and water quality parameters, and the relationship coefficient R² was 0.756. This study provides important information and perspectives for the improvement and implementation of standards for swimming pool water.
... One such alternative disinfection technique is electrochemically generated chlorine (or salt water pools) which works by passing an electric current through a concentrated salt solution (sodium chloride) to produce hypochlorous acid (HOCl) and hypochlorite ions (OCl − ) as the primary oxidants ( U.S. Army Center for Health Promotion and Preventive Medicine, 2006 ). Previous studies have shown that when compared to pools disinfected with chlorine, salt water pools had lower levels of HAAs (dichloroacetic acid and trichloroacetic acid) and trichloroacetaldehyde, but higher levels of Br-DBPs, likely due to bromide impurities in the sodium chloride ( Lee et al., 2009( Lee et al., , 2010. This increase in bromide is an important factor to monitor because previous studies show that dichloroacetic acid and trichloroacetic acid do not significantly contribute to the cytotoxicity or genotoxicity of pool waters ( Yeh et al., 2014 ). ...
... Brominated DBPs (Br-DBPs) are of interest due to their elevated levels of toxicity compared to their chlorinated analogues Wagner and Plewa, 2017 ). Previous salt water pool studies, which measured a smaller number of DBPs, have attributed the formation of Br-THMs, Br-HAAs, and Br-HANs to bromide present in sodium chloride and emphasized the importance of using high purity sodium chloride ( Beech et al., 1980 ;Whitaker et al., 2003 ;Lee et al., 2010Lee et al., , 2009. Ion chromatography analysis of the sodium chloride used in the salt water pool in this study revealed that the salt contained approximately 0.05% bromide. ...
Disinfectants are added to swimming pools to kill harmful pathogens. Although liquid chlorine (sodium hypochlorite) is the most commonly used disinfectant, alternative disinfection techniques like electrochemically generated mixed oxidants or electrochemically generated chlorine, often referred to as salt water pools, are growing in popularity. However, these disinfectants react with natural organic matter and anthropogenic contaminants introduced to the pool water by swimmers to form disinfection byproducts (DBPs). DBPs have been linked to several adverse health effects, such as bladder cancer, adverse birth outcomes, and asthma. In this study, we quantified 60 DBPs using gas chromatography-mass spectrometry and assessed the calculated cytotoxicity and genotoxicity of an indoor community swimming pool before and after switching to a salt water pool with electrochemically generated chlorine. Interestingly, the total DBPs increased by 15% upon implementation of the salt water pool, but the calculated cytotoxicity and genotoxicity decreased by 45% and 15%, respectively. Predominant DBP classes formed were haloacetic acids, with trichloroacetic acid and dichloroacetic acid contributing 57% of the average total DBPs formed. Haloacetonitriles, haloacetic acids, and haloacetaldehydes were the primary drivers of calculated cytotoxicity, and haloacetic acids were the primary driver of calculated genotoxicity. Diiodoacetic acid, a highly toxic iodinated DBP, is reported for the first time in swimming pool water. Bromide impurities in sodium chloride used to electrochemically generate chlorine led to a 73% increase in brominated DBPs, primarily driven by bromochloroacetic acid. This study presents the most extensive DBP study to-date for salt water pools.
... Suda bulunan kanser risk faktörleri duş alırken, banyo yaparken ve yüzerken cilt yoluyla vücuda nüfuz eder [49]. [21], [50]. Erkeklerde ve kadınlarda dermal absorpsiyon yoluyla yaşam boyu kanser riski maruziyeti sonuçlarına göre THM'den kaynaklanan kanser riskine katkıyı sırasıyla %52 kloroform, %32 bromodiklorometan, %14 diklorobromometan ve %2 bromoform oluşturmaktadır. ...
... İnhalasyon maruziyeti, banyo yapma, duş alma ve yemek pişirme gibi su kullanımı sırasında uçucu bileşikler nedeniyle meydana gelmektedir [21], [50]. Duş alırken ortaya çıkan ortam, uçucu bileşiklerin en fazla olduğu ortam olarak tespit edilmiş ve dolasıyla en fazla inhalasyon kaynaklı kanser riski bu ortamda oluşmaktadır. ...
... Public swimming pools used for recreational activities are usually disinfected by chlorine or chlorine based disinfectants, such as salts of hypochlorous acid (HClO) and sodium dichlorocyanurat (C 3 Cl 2 N 3 NaO 3 ) (Angione et al.2010). Disinfectant chlorine agents interact very readily by competitive favorable chemical reactions with natural organic matter (NOM) and form chlorinated disinfection by-products such as combined chlorine (carcinogenic trihalomethanes (THMs), haloacetic acids (HAAs) or chloramines) (Ahmed et al. 2019;Chu et al. 2013;Hang et al. 2016;Keuten et al. 2012;Kim et al. 2017;Lee et al. 2009;Momeniha et al. 2021;Tsamba et al. 2020;Xiaomao et al. 2014;Xiaolu et al. 2015). Unsuitable ventilation in indoor swimming pools and chlorination by-products stimulate the increased risk of adverse health effects, such as developing upper and lower negative respiratory allergy effects, eye irritation, skin allergies and other allergic reactions (Angione et al. 2010;Chu et al. 2013;Hang et al. 2016;Keuten et al. 2012;Lee et al. 2009;Li et al. 2020;Lourencetti et al. 2012;Lu et al. 2008;Swinarew et al. 2020;Tardif et al. 2016;Teo et al. 2015). ...
... Disinfectant chlorine agents interact very readily by competitive favorable chemical reactions with natural organic matter (NOM) and form chlorinated disinfection by-products such as combined chlorine (carcinogenic trihalomethanes (THMs), haloacetic acids (HAAs) or chloramines) (Ahmed et al. 2019;Chu et al. 2013;Hang et al. 2016;Keuten et al. 2012;Kim et al. 2017;Lee et al. 2009;Momeniha et al. 2021;Tsamba et al. 2020;Xiaomao et al. 2014;Xiaolu et al. 2015). Unsuitable ventilation in indoor swimming pools and chlorination by-products stimulate the increased risk of adverse health effects, such as developing upper and lower negative respiratory allergy effects, eye irritation, skin allergies and other allergic reactions (Angione et al. 2010;Chu et al. 2013;Hang et al. 2016;Keuten et al. 2012;Lee et al. 2009;Li et al. 2020;Lourencetti et al. 2012;Lu et al. 2008;Swinarew et al. 2020;Tardif et al. 2016;Teo et al. 2015). At the other side, depressed levels of chlorine could not efficiently disinfect swimming pool water and kill pathogenic organisms. ...
Colorimetric fiber optic sensor was developed for determination of total and residual chlorine in water. Developed sensor is based on absorption and detects values in the red, green, blue color space which is converted in user-oriented hue, saturation, value color model. Hue, saturation, value color model is enforced to simplify determination of the key chemical parameters concentration in water. Concentrations of total and residual chlorine in swimming pool water samples were measured by standard chemical laboratory analysis and compared with concentrations obtained by sensor, to approve the repeatability and effectiveness of the innovative method for measurements in water. In addition, results obtained by analysis of surface water and swimming pool water were compared in order to prove effectiveness of sensor for different water media. The absolute value between the two compared methods for the total chlorine concentrations was in the range from 0.014 to 0.067 mg/L and for residual chlorine from 0.002 to 0.06 mg/L. The linearity of calibration curve, limit of detection and quantitation, accuracy and precision are investigated to prove the validation of the analytical procedure to determine chlorine species by sensor. Used sensor method with its advantages (efficiency, low cost, simple use, small size, repeatability) was used on laboratory scale for the first time separately for total chlorine and residual chlorine and demonstrates possibility to replace expensive standard analytical laboratory equipment.
... A class of DBPs called chloramines which includes trichloramine (a gas that gives indoor pools their typical smell) has been found to be unstable in water and able to easily penetrate the lower airways of swimmers (Schmalz et al, 2011). Trihalomethanes (THMs), another class of DBPs which has been found to be carcinogenic in rodents , have been detected in pool water and found to be seven times higher in the blood and exhaled breaths of swimmers after swimming in indoor pools (Lee & Zoh, 2009). More time spent swimming in chlorinated swimming pools was associated with increased THM concentrations . ...
... The positive health gains from swimming might be increased by reducing the potential health risks of the pool water caused by DBPs and other chemicals that lead to respiratory discomfort and could also be potentially mutagenic. Research findings recommended increasing air circulation in indoor pool settings to reduce the concentrations of DBPs as well as choosing a suitable disinfection method (Lee & Zoh, 2009); however, it is difficult to define "suitable" as studies are lacking directly comparing the DBPs generated by the wide variety of disinfectants currently used alone and in combination, including salt water electrolysis, chlorine, bromine, and ozone. Currently, apart from Germany and Denmark, few specific guidelines appear to exist worldwide or in the U.S. for the concentrations of DBPs in the swimming pool environment (Carter & Joll, 2017). ...
... The rule mandates utilities that using chlorine for disinfection, to remove total organic carbon as a measure for reducing DBP precursors. Kim 2009;Chang et al. 2010;Pardakhti et al. 2011 andLee et al. 2009). ...
Jar tests were conducted to simulate the conventional processes of water treatment. Enhanced coagulation used the traditional alum that is already applied in water treatment in Egypt, with a comparison with ferric chloride and a mixture of alum and ferric chloride, the strategy of enhanced treatment adopted mainly organic matter and THMs beside turbidity, so the doses of coagulant were increased to achieve better removal of THMs which have an health issue. Conventional treatment processes including adding aluminum sulfate or ferric chloride to the raw water followed by coagulation, sedimentation, and rapid sand filtration are important steps in water purification. They reduced the organic matter to about 42% and THMs to 37 using the baseline dose (25 mg/l). The enhanced coagulation process by increasing the dose of alum reduced the total organic carbon and THMs to 57 % and 54 % respectively. Using ferric chloride at a baseline dose reduced TOC and THMs by 40 % and 36% respectively, while enhanced coagulation by increasing the dose of ferric chloride (at a dose of 35 mg/l) raised up the removal of TOC and THMs to 47 % and 44% respectively. The dual coagulant of alum and ferric chloride achieved 47% removal of TOC and 36% for THMs at a dosage of 25 mg/l, while the enhanced coagulation by increasing the dose of duel coagulant of alum and ferric chloride (35 mg/l) raising up the removal of TOC to 61% and THMs to 50%. The advantage of the dual coagulant is the higher reduction of residual aluminum and THMs, this is attributed to the enhancement of flocculation which creates activated adsorption sites of flocs surfaces.
... Compared with the DBP concentrations in swimming pools using other disinfection techniques, the concentrations of regulated THMs and HAAs in TCCA-disinfected swimming pools are higher than those in swimming pools disinfected using chlorine dioxide, UV/chlorine, and O 3 /chlorine, but generally lower than those in chlorine, CSI/chlorine and electrochemically generated mixed oxidants (Carter and Joll, 2017;Allen et al., 2021;Granger and Richardson, 2022;Simard et al., 2013;Lee et al., 2009). Additionally, the composition of the TCCA studied in the disinfected swimming pool is similar to chlorine, CSI/chlorine and electrochemically generated mixed oxidants, which feature high Cl-DBP concentrations, especially Cl-HAAs (Allen et al., 2021;Granger and Richardson, 2022;Wang et al., 2020). ...
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, approximately 88%, 49%, 97%, 55%, and 97% 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.
... This is probably because the TOC and free chlorine concentrations were higher in SP-B and THM formation is higher than that in SP-A. 39,40,45 HAAs, which were the most studied DBPs after THMs, accumulate in pool waters due to their non-volatile structures and pool treatment equipment being inefficient in their removal. 11,41,60 HAAs were determined to be at higher concentrations compared to other DBPs in the pool waters investigated in this study. ...
Monitoring the disinfection process and swimming pool water quality is essential for the prevention of microbial infections and associated diseases. However, carcinogenic and chronic-toxic disinfection by-products (DBPs) are formed with reactions between disinfectants and organic/inorganic matters. DBP precursors in swimming pools originate from anthropogenic sources (body secretions, personal care products, pharmaceuticals, etc.) or chemicals used in pools. Temporal (48 weeks) water quality trends of trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and halonitromethanes (HNMs) in two swimming pools (SP-A and SP-B) and precursor−DBP relationships were investigated in this study. Weekly samples were taken from swimming pools, and several physical/chemical water quality parameters, absorbable organic halides (AOX), and DBPs were determined. THMs and HAAs were the most detected DBP groups in pool water. While chloroform was determined to be the dominant THM compound, dichloroacetic acid and trichloroacetic acid were the dominant HAA compounds. The average AOX concentrations were measured to be 304 and 746 μg/L as Cl − in SPA and SP-B, respectively. Although the amount of AOX from unknown chlorinated by-products in SPA did not vary temporally, a significant increase in unknown DBP concentrations in SP-B was observed over time. AOX concentrations of chlorinated pool waters were determined to be an important parameter that can be used to estimate DBP concentrations.
... Natural ventilation through opening windows is commonly adopted in most ISPs to reduce electricity costs and may also decrease exposure to volatile DBPs. Previous studies indicated that the estimated excess lifetime cancer risk of exposure to chloroform in ISPs can mainly be attributed to the inhalation exposure route (Lee et al. 2009;Chen et al. 2011;Pándics et al. 2018). Without precise information on the concentration profiles of chloroform in ISP air, there are challenges to managing the air quality and assessing the health risks to the exposed population. ...
The release of chloroform from water to air in an indoor swimming pool (ISP) exhibits complex physicochemical interactions among many variables, including environmental conditions, occupant activities, and geometry of the ISP. By combining the relevant variables, a structured mathematical model, the double-layer air compartment (DLAC) model, was developed to predict the level of chloroform in ISP air. A physical parameter, the indoor airflow recycle ratio (R), was incorporated into the DLAC model due to internal airflow circulation resulting in the ISP structural configuration. The theoretical R-value for a specific indoor airflow rate (vy) can be found by fitting the predicted residence time distribution (RTD) to the simulated RTD from computational fluid dynamics (CFD), showing a positive linear relationship with vy. The mechanical energies induced by occupant activities were converted into a lumped overall mass-transfer coefficient to account for the enhanced mass transfer of chloroform from the water into the air and mixing in ISP air. The DLAC model predicted that chloroform air concentrations were statistically less accurate without considering the influence of R compared with the online open-path Fourier transform infrared measurements. A novel index, the magnitude of emission (MOE) from swimmers, was linked to the level of chloroform in ISP water. The capability of the DLAC model associated with the MOE concept may facilitate upgrading the hygiene management of ISPs, including the ability to administer necessary chlorine additives in pool water and monitor the chloroform in ISP air.
... Chemical disinfection of water contributes to the creation of harmful disinfection byproducts. Many of them have adverse health effects [26][27][28]. ...
Pseudomonas fluorescens is one of the first colonizers of bacterial biofilm in water systems and a member of opportunistic premise plumbing pathogens (OPPPs). The aim of this study was to examine the effect of UV light and sodium hypochlorite on the formation and destruction of mature P. fluorescens biofilm on ceramic tiles. Planktonic bacteria or bacteria in mature biofilm were exposed to UV light (254 nm) for 5, 20 s. and to 0.4 mg/L sodium hypochlorite for 1 min. Mature biofilm was also exposed to increased concentration of sodium hypochlorite of 2 mg/L for 0.5, 1 and 2 h and combined with UV. Prolonged action of sodium hypochlorite and an increase in its concentration in combination with UV gave the best results in the inhibition of biofilm formation after the pre-treatment and destruction of mature biofilm. The effect of hyperchlorination in combination with UV radiation shows better results after a long exposure time, although even after 120 min there was no completely destroyed biofilm. Furthermore, the mechanism of the effect of combined methods should be explored as well as the importance of mechanical cleaning that is crucial in combating bacterial biofilm in swimming pools.
... Evidence from various toxicological and epidemiological studies on the adverse health effects of disinfection by-products (DBPs) has raised concerns about the chemical safety of swimming pools. Frequently studied and mentioned harmful by-products are trihalomethanes (THMs) [12][13][14][15][16]. Mainly, the THM concentration depends on the method of pool water disinfection. ...
Pool water must meet certain chemical and microbiological conditions to ensure high water quality and a safe environment for users. A recreational swimming pool treated with a combined disinfection method (chlorination and UV radiation) was monitored for 18 months. Selected chemical and microbiological parameters of the indoor freshwater pool were analyzed, and the in vivo presence of Pseudomonas aeruginosa biofilm was assessed and further correlated to the type of disinfection. P. aeruginosa isolated from biofilm was further examined to determine the effects of combined disinfection methods on the formation and destruction of mature biofilm in vitro. The in vitro application of the combined disinfection methods led to the inhibition of planktonic P. aeruginosa biofilm formation (68.9% compared to the control group) and were more effective in the partial destruction of mature biofilm than individual disinfection methods (from 25.4 to 26.3%). The obtained results indicate the better microbiological and chemical quality of pool water when combined disinfection was applied. Our results contribute to developing the optimization of pool water disinfection methods and biofilm control.
... On the other hand, water distribution networks, due to extended contact time between chlorine residuals and THM precursors in the system, provide suitable environments for THM formation (Al-Omari et al. 2014). Higher chlorine residuals and the presence of NOM may augment the formation of THMs (Singh et al. 2012;Lee et al. 2010). ...
Central composite rotatable design (CCRD) was employed to optimize initial temperature (ºC), ramp function (ºC/min) and salt addition for trihalomethane extraction/quantification from the drinking water distribution network in Ratta Amral, Rawalpindi., Pakistan. Drinking water samples were collected from the treatment plant, overhead reservoir and consumer’s taps. The USEPA method for trihalomethane detection 551.1 via gas chromatography was applied using liquid–liquid extraction. The experiments with input variables for sample preparation and operational conditions were performed in a randomized order as per design of experiment by central composite rotatable design and responses were evaluated for model development. A significant ( p = 0.005) two-factor interaction model was optimized. Initial temperature was observed to be insignificant ( p = 0.64), while ramp function ( p = 0.0043) and salt addition ( p = 0.04) were significant. Product of salt addition and ramp was significant ( p = 0.004), while product of initial temperature and salt addition was insignificant ( p = 0.008). With a desirability function of 0.97, an initial temperature of 50 ºC, 6 ºC rise/min to 180 ºC and 0.5 g salt were optimized. It was found that development and optimization of the analytical methods for rapid trihalomethane detection would improve optimization of the current treatment practices in the country.
... Lee et al., 2009) Chlorine and ChloraminesPeople experienced a serious of infection after a party where they spend(Kaydos-Daniels et al., 2008) ...
Water contamination through anthropogenic and industrial activities has led to the emergence and necessity of disinfection methods. Chlorine and bromine gases, often used to disinfect water, resulted in the by-product formation by reacting with organic matter. The Disinfectant by-products (DBP) led to the formation of Trihaloaceticacid (TAA), Trihalomethane (THM), and other minor components. The release of chemicals has also led to the outbreak of diseases like infertility, asthma, stillbirth, and types of cancer. There are new approaches that are found to be useful to compensate for the generation of toxic by-products and involve membrane technologies, namely reverse osmosis, ultrafiltration, and nanofiltration. This review mainly focuses on the toxicology effects of DBPs and various approaches to mitigate the same. The health hazards caused by different DBPs and the various treatment techniques available for the removal are discussed. In addition, a critical comparison of the different removal techniques was discussed.
... Therefore, the cleaning workers in the swimming pools and spas are exposed to numerous disinfection byproducts (DBPs) that are present in the indoor air of the pool areas. These include irritative compounds such as chloramines and trihalomethanes (THMs) and have been the subject of several previous studies (Caro and Gallego 2007;Zwiener et al. 2007;Lee et al. 2009Lee et al. , 2010Weaver et al. 2009;Richardson et al. 2010;Bessonneau et al. 2011;Schmalz et al. 2011a;Hansen et al. 2012;Westerlund et al. 2015). DBPs are formed in the reactions of the disinfecting chemicals (often NaClO) and organic or inorganic impurities, originating for example from toiletries, sweat, and urine (Hery et al. 1995;Judd and Black 2000;Hsu et al. 2009;Hansen et al. 2012). ...
Swimming pools and spas require a high hygiene level, and therefore constant cleaning. In this study, cleaning workers’ exposure to volatile organic compounds (VOCs), trichloramine (TCA), and particulate matter (PM) in the swimming pools and spas were evaluated. Also, statistical methods were employed to determine what activities affect the exposure to disinfection byproducts (DBPs). The study was conducted in 32 swimming pools and spas. The measurement locations were pool areas, bathrooms, and locker rooms, both during cleaning and opening hours. During the cleaning, the total volatile organic compound (TVOC) concentrations were low, on average 96, 251, and 91 µg/m³ for locker rooms, bathrooms, and pool areas, respectively. Similarly, during the opening hours, the TVOC concentrations were on average 78, 125, and 83 µg/m³, for locker rooms, bathrooms, and pool areas, respectively. This is in line with previous studies investigating cleaning work in other environments. The most prevalent compounds during the cleaning were 2-(2-butoxyethoxy)ethanol (DEGBE), 2-(2-ethoxyethoxy)ethanol (DEGEE), 2-butyl-1-octanol, trichloromethane (chloroform), decamethylcyclopentasiloxane (D5), and carbon tetrachloride. The most prevalent compounds during the opening hours were D5, D-limonene, carbon tetrachloride (bathrooms and pool areas), and trichloromethane (bathrooms and pool areas). The TCA concentrations during the cleaning in the bathrooms and pool areas were on average 60 and 67 µg/m³, respectively, and during the opening hours, 28 and 122 µg/m³, respectively. The use of disinfectants was found to increase the TCA concentration in the bathrooms, while the other cleaning products did not. Even though the TCA concentrations were below the WHO’s guideline and the Finnish occupational exposure limit value of 500 µg/m³, the measured TCA levels were occasionally high enough to pose a risk of irritative symptoms. The PM concentrations were low, both in the real-time monitoring (aerodynamic diameter, Dae ≤ 15 µm) and inhalable dust samples (Dae ≤ 100 µm). Highest measured inhalable dust concentration was 350 µg/m³, well below the Finnish occupational limit value of 5,000 µg/m³ for organic inhalable dust.
... 22,23 It turns out that THMs are highly volatile, and some reports claim that THMs are absorbed via the respiratory route. [24][25][26] Erdinger et al 27 demonstrated that the content of THMs in swimmers' blood is correlated with their content in the ambient air of swimming pools and not with the content in the water, and with a direct impact of swimming intensity on THM accumulation in the organism of swimmers. ...
Concerns have been raised regarding the potential negative effects on human health of water disinfectants used in swimming pools. Among the disinfection options, the approaches using chlorine‐based products have been typically preferred. Chlorine readily reacts with natural organic matter that are introduced in the water mainly through the bathers, leading to the formation of potentially harmful chlorination by‐products (CBPs). The formation of CBPs is of particular concern since some have been epidemiologically associated with the development of various clinical manifestations. The higher the concentration of volatile CBPs in the water, the higher their concentration in the air above the pool, and different routes of exposure to chemicals in swimming pools (water ingestion, skin absorption, and inhalation) contribute to the individual exposome. Some CBPs may affect the respiratory and skin health of those who stay indoor for long periods, such as swimming instructors, pool staff, and competitive swimmers. Whether those who use chlorinated pools as customers, particularly children, may also be affected has been a matter of debate. In this article, we discuss the current evidence regarding the health effects of both acute and chronic exposures in different populations (work‐related exposures, intensive sports, and recreational attendance) and identify the main recommendations and unmet needs for research in this area.
... The most dangerous is the effects of DBPs, which isare not noticed in many years of regular bathing. Asthma, bladder cancer, and atopic dermatitis are being increasingly recognized as risks to the health of pool users and facility employees [2,4,39,40]. It has also been confirmed that microcontaminants produced as DBPs of various enzymes, produced as DBPs, lead to the generation of oxidative stress in the cells of living organisms [41]. ...
The washings remaining after rinsing the pressure filters in swimming pool facilities constitute a stream representing the full array of impurities found in these waters. To separate individual frac-tions of these impurities, pressure membrane processes, ultra-, and nanofiltration have been used. The washings from water circuits in pools of different intended use and with various impurities were analyzed. Six fractions were obtained, with an apparent molar mass of: >200; <200; 200–30; <30kDa; 30kDa–300Da; <300Da. The quality of each fraction was evaluated in terms of physicochemical characteristics – concentration of total organic carbon (TOC), absorbable organic halogens (AOX) – and ecotoxicological characteristics (Microtox®, Artemia salina). The distribution of the impuri-ties in individual fractions varied. The highest concentrations of impurities were observed in the washings from the swimming pool, in the >200kDa fraction, 7.87, and 2.85mgCl/L. However, in the fraction below 300Da, TOC and AOX concentrations reached 0.93 and 0.47mgCl/L, respec-tively. Itshould be noted that all analyzed samples of impurity fractions were characterized by low/nontoxicity. There was no correlation between selected physicochemical parameters, or the concentration of TOC and AOX, and the toxicity level
... 22,23 It turns out that THMs are highly volatile, and some reports claim that THMs are absorbed via the respiratory route. [24][25][26] Erdinger et al 27 demonstrated that the content of THMs in swimmers' blood is correlated with their content in the ambient air of swimming pools and not with the content in the water, and with a direct impact of swimming intensity on THM accumulation in the organism of swimmers. ...
Concerns have been raised regarding the potential negative effects on human health of water disinfectants used in swimming-pools. Among the disinfection options, the approaches using chlorine-based products have been typically preferred. Chlorine readily reacts with natural organic matter that are introduced in the water mainly through the bathers, leading to the formation of potentially harmful chlorination by-products (CBPs). The formation of CBPs is of particular concern since they have been epidemiologically associated with the development of various clinical manifestations. The higher the concentration of these volatile CBPs in the water, the higher their concentration in the air above the pool, and different routes of exposure to chemicals in swimming-pools (water ingestion, skin absorption and inhalation) contribute to the individual exposome. CBPs may affect the respiratory and skin health of those who stay indoor for long periods, such as swimming instructors, pool staff, and competitive swimmers. Whether those who use chlorinated-pools as customers, particularly children, may also be affected has been a matter of debate. In this article, the EAACI Joint Task Force of the Working Group of Allergy, Asthma & Sports and the Interest Groupf of Environmental & Occupational Allergy discusses the current evidence regarding the health effects of both acute and chronic exposures in different populations (work-related exposures, intensive sports and recreational attendance) and identify the main recommendations and unmet needs for research in this area.
... Zeng et al. (2020) proposed for the disinfection three methods, i.e., ultraviolet irradiation (UV) and two UV-based advanced oxidation processes (UV-AOPs) (UV/ hydrogen peroxide, UV/H 2 O 2 and UV/peroxymonosulfate, UV/ PMS). The use of chemicals for water disinfection, which simultaneously have strong oxidizing properties, causes the formation of disinfection by-products (DBPs) such as trihalomethanes (THM) (Lee et al., 2009), organic acids (Zhang et al., 2020), aldehydes and other unidentified compounds (Lee et al., 2010). Some substances occurring in water, such as i.e. bromides and natural organic matter (NOM), are the precursors of halogenated DBP in drinking water (Yin et al., 2020). ...
The aim of the research was to assess changes in the content of biodegradable dissolved organic carbon and assimilable organic carbon after disinfection process in groundwater from a backyard well and in surface water from a dam reservoir, from which a water supply company collects and treats water. Two types of disinfection processes were carried out, chlorination and UV enhanced chlorination, respectively. Sodium hypochlorite was applied as the disinfectant used in the tested water treatment plant. The content of selected forms of organic carbon, i.e. total organic carbon, dissolved organic carbon, biodegradable dissolved organic carbon and assimilable organic carbon, was determined in the waters before and after disinfection processes. The studies have shown that the applied disinfection processes significantly reduce the biodegradable dissolved organic carbon and assimilable organic carbon content in surface water sampled from the dam reservoir. Assimilable organic carbon concentration in water after 30 min and 24 h of contact decreased by 75.0 and 81.3%, respectively, biodegradable dissolved organic carbon by 50.0 and 55.3%. The results obtained in this study provide valuable information on the impact of the chemical oxidants most commonly used for disinfection on the content of biodegradable organic matter. This will allow to select appropriate disinfection methods to prevent secondary development of microorganisms in the distribution system. In these studies, the usage of monitoring of biodegradable dissolved organic carbon and assimilable organic carbon content after disinfection processes to assess the risk arising from a secondary microbial growth was considered. The proposal of a new approach to the content of biodegradable dissolved organic carbon and assimilable organic carbon after disinfection processes is aimed at encouraging the extension of research assessing the risk associated with water consumption depending on the content of biodegradable matter.
... Chlorine-based disinfectants threaten human health, agricultural production, environmental quality and aquatic ecosystem health in a variety of ways by (1) reaction with Natural Organic Matter (NOM) or bromide in raw-water leads to the formation of DBPs such as Trihalomethanes (THMs), bromates, effl uent and other chemical compounds which poses acute toxicity to human health, aquatic ecosystem and other consumers [13][14][15][16][17]. (2) The direct toxic effect of chlorinebased chemicals on the aquatic organisms including vegetative bacteria, mycobacteria, viruses, and fungi by destroying their cell membranes, the cell hydrophobicity, as well as total Adenosine Triphosphate (ATP) [18,19]. ...
Because of the current situation regarding the Covid-19 pandemic in more than 200 countries and territories, an early discussion is proposed on the use of chlorinebased disinfectants as an important precautionary measure to disinfect the surfaces and kill the Covid-19. However, the excessive use of chlorine-based disinfectants will
surely make the highest residual concentrations in the water, soil, and other environmental components by various means such as surface runoff and leaching, etc. Crossing
the permissible limits in water and soil system and in other environmental components will pose risks to human health in the form of skin, eyes, cancer, and other associated
diseases. Similarly, it may also decline the agricultural production by excessive salt (Cl-
) accumulations (salinization) and will also threaten the aquatic and wild ecosystems.
Therein, the ecological integrity assessments regarding the use of chlorine-based disinfectants in the current situation are very much important. Meanwhile, this will open a
new area of interest for the researcher and would be of great importance to investigate its critical levels in the environmental components and its potentially toxic effects.
... 24 For adults in SPWs, IR, ET, EF, and ED were 25 mL h À1 , 1.3 h per event, 120 event per year, and 30 years, respectively. 25 For DWs, IR was 2.14 L per day for males and 2 L per day for females, 26 EF was 365 days per year, and ED was the same as ATL. The PC was 1-3 Â 10 À3 cm h À1 . ...
A prevalent group of disinfection by-products (DBPs), i.e., haloacetic acids (HAAs), have raised significant public concern due to their high frequency of occurrence, considerable concentrations and potent toxicity. This study investigated the environmental occurrence of HAAs and the corresponding predicted human exposure to two important water matrices where humans are frequently and long-term exposed, i.e., swimming pool waters (SPWs) and drinking waters (DWs), in Shanghai, China. The sum of five HAAs in SPWs was 241 μg L⁻¹ on average (dominated by dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA)), four times as much as its maximum contaminant level (MCL) regulated by the Environmental Protection Agency (EPA) in DWs. The maximum HAA concentration in DWs was 35 μg L⁻¹, with chloroacetic acid (CAA) as the most dominant compound. The higher concentrations (reflected by total organic carbon (TOC), dissolved organic carbon (DOC), and UV254) and more categories (body fluids and personal care products in addition to natural organic matter) of organic contaminants and the higher chlorine in SPWs should be responsible for the differentiated HAA yield and speciation. The qualification rates of samples have been evaluated. The power function models correlating HAAs with multiple water quality parameters were developed with correlation coefficients of 0.614 and 0.798 for SPWs and DWs respectively. These models may provide the preliminary insights on how to minimize HAA formation by grasping the relative importance of each parameter and how to build the framework to predict HAA formation in untreated source water or SPWs subjected to chlorination. The predicted carcinogenic and non-carcinogenic risks of humans exposed to SPWs and DWs with HAAs were within the acceptable levels.
... Les THM ont été détectés et quantifés à des concentrations importantes dans les eaux et l'air des piscines ; ils représentent de 5 à 10% des composés organohalogénés totaux (méthode AOX). Les molécules majoritaires sont le chloroforme (CHCl3) ou le bromoforme (CHBr3) lorsque l'eau -désinfectée au chlore-est riche en bromures (comme l'eau de mer) ou lorque l'eau est désinfectée au brome (Aggazzotti et Predieri, 1986;Beech et al., 1980;Erdinger et al., 2004;Fantuzzi et al., 2001;Lee et al., 2009;Nieuwenhuijsen et al., 2000;Simard et al., 2013;Weaver et al., 2009 ;Lourencetti et al., 2012;Parinet et al., 2012;Manasfi et al., 2016). Les THM incluent également le dichlorobromométhane et le bromodichlorométhane. Le tableau 3-B de l'annexe 3 présente les concentrations médianes trouvées dans les eaux de piscine de différents pays. ...
... Human health risks due to DBPs exposure can be mitigated through the adoption of appropriate control strategies. Development of a specific DBPs control strategy is based on a number of ISP design and management factors including, pool types (e.g., leisure pools, lap pools, hot tubs) (Daiber et al., 2016;Hery et al., 1995), source water quality (e.g., organic and inorganic precursors, pH, temperature) (Hansen et al., 2012;Kanan and Karanfil, 2011;Kim et al., 2002;LaKind et al., 2010;Simard et al., 2013), disinfection processes (methods) (e.g., UV treatment, chlorination, ozonation) (Lee et al., 2009;McMaster, 2011;Richardson et al., 2010), bathers (e.g., number, behavior, and personal hygiene condition) (Chu and Nieuwenhuijsen, 2002;Daiber et al., 2016;Kristensen et al., 2010), and air ventilation conditions (Bessonneau et al., 2011;Jacobs et al., 2007). ...
Disinfection by-products (DBPs) in public indoor swimming pools (ISP) are a major human health risk concern. Various DBPs control strategies have been developed as an integral part of ISP management; however, these strategies are associated with different energy and resource consumption and environmental impacts. In this study, a process-based life cycle assessment (P-LCA) framework is developed for determining the environmental impacts of DBPs control strategies in ISP management. The developed framework requires ISP operation information such as energy, water, and chemical use, and concentration data under each DBPs control strategy as inputs. The ReCipe2016 midpoint method is used to process the inputs and quantify the lifecycle impacts in terms of three categories: energy, water and chemicals. Based on the outputs, the best strategy is selected using the TOPSIS method. The developed framework is applied to an ISP located in Vancouver (Canada) to evaluate seven DBPs control strategies associated with various air circulation rates. The DBPs concentration data were sourced from a previous sampling campaign. The results show that energy use is the main contributor (87–94%) to the total environmental impacts as compared to chemical and water use (6–13%). Among the tested strategies, reduction of fan speed can yield maximum environmental benefits without compromising the DBPs control performance. On the other hand, supply of 100% fresh air at normal fan speeds results in higher environmental impacts compared to a baseline case despite the lower DBPs releases. The proposed P-LCA framework can facilitate pool operators in selecting low impact DBPs control strategies for sustainable ISP management.
... Similarly, CR inge , CR derm , and CR inha are total carcinogenic risks for the total OPEs through oral ingestion, dermal contact, and inhalation absorption, respectively. The same SF are adopted for the SF inge,i , SF derm,i , and SF inha,I because of the shortage of available data as other studies (Lee et al., 2009;Li et al., 2018b;Wang et al., 2019). The values of RfD and SF for OPEs are listed in Table S3 of the Supplementary Information. ...
Organophosphate esters (OPEs) are extensively used as flame retardants and plasticizers in China; however, their potential carcinogenicity causes great concern. To date, their environmental distribution in water samples from the lower Yangtze River Basin still remains uncharacterized. This study systematically investigated the occurrence and spatial distribution of 13 OPEs, as well as their associated potential risks, in water samples from the lower Yangtze River and its 88 major inflowing rivers. The total OPE (ΣOPE) concentrations ranged from 55.6 to 5071 ng/L, with a median of 144 ng/L. Among them, halogenated OPEs were the dominant group with an average of 61.6%, and tris(1-chloro-2-propyl) phosphate (12.6–450 ng/L, median: 53.38 ng/L) and tris(2-choroethyl) phosphate (11.0–1202 ng/L, median: 36.4 ng/L) were the most abundant OPEs. Significantly different concentrations were found with spatial variations (p < 0.01), and were higher in southern cities than in northern cities of the lower Yangtze River Basin. Principal component analysis with multiple linear regression and Spearman correlations showed that the main sources were likely emission of vehicular and marine traffic. Ecological risk analysis showed that the risk quotient (RQ) values of samples remained below 1, but the percentage of 0.1 < RQ ≤ 1 was 26.9%, indicating a medium risk of OPEs in water samples. Moreover, ethylhexyl diphenyl phosphate predominantly contributed to the ecological risk, accounting for >89.2% of the total ecological risk of ΣOPEs. However, the total non-carcinogenic and carcinogenic risks of ΣOPEs were negligible at the detected concentrations, even in a high exposure scenario. The risks from major inflowing rivers of the lower Yangtze River were almost one order of magnitude higher than those of the mainstream lower Yangtze River.
... Several DOM properties are closely related to the occurrence of DBP precursors (such as THMs), and/or can be used as descriptors for predicting their FPs. This includes DOM's spectroscopic properties (i.e., ultraviolet absorbance at l ¼ 254 nm or SUVA 254 (Hua et al., 2015) and fluorescent signal (Roccaro et al., 2009)), its composition (e.g., the presence of protein-like organic matter (Chu et al., 2010), aromatic moieties (Hua et al., 2015), and suspended particulate matter (Hou et al., 2018)), and the bulk concentration of DOM, which can be accounted as total organic carbon, TOC (Lee et al., 2009), or as dissolved organic carbon, DOC (Peng et al., 2016). ...
In order to understand and minimize the formation of halogenated disinfection by-products (DBPs), it is important to investigate how dissolved organic matter (DOM) contributes to their generation. In the present study, we analysed the DOM profile of water samples from the Barcelona catchment area by high resolution mass spectrometry (HRMS) and we studied the changes after chlorination. Chlorination produced significant changes in the DOM, decreased the average m/z and Kendrick mass defect (KMD) of their spectra and decreased the number and abundance of lignin-like features. The Van Krevelen (VK) fingerprint exhibited several noticeable changes, including the appearance of highly oxidized peaks in the tannin-like region (average O/C, 0.78 ± 0.08), the appearance of features with low H/C and the disappearance of more than half of the lipids-like features. Up to 657 halogenated peaks were generated during sample chlorination, most of which in the condensed hydrocarbons-like and the lignin-like region of the VK diagram.
Around 200 features were found to be strongly correlated (ρ ≥ 0.795) to the formation potential of trihalomethanes (THMs) and 5 were correlated with the formation potential of haloacetonitrile (HANs). They all were plotted in the lignin fraction of the VK diagram, but both groups of features exhibited different nitrogen content: those features related to HANs FP had at least one nitrogen atoms in their structures, whilst those related to THMs did not.
... The presence of these species in raw water facilitates the reproduction of microorganisms in drinking water distribution systems. They also induce the utilization of a high chlorine dose and act as the precursor for the formation of harmful disinfection by-products (DBP), such as trihalomethanes (THMs), which are classified as potentially carcinogenic chlorine organic compounds (Lee et al., 2009). They can cause a reducing in the efficiency of water treatment facilities by interfering with various oxidants, increasing the solubility of heavy metals due to complexation with metals and adsorbed organic pollutants (Yang et al. 2007). ...
Removal of natural organic matter from water using chemically activated coffee husk The presence of natural organic matter (NOM) in source water has posed many challenges for conventional water treatment facilities. Small organic acids, such as humic acid, present in NOM, have a high potential to influence the performance of water treatment processes. Uncontrolled application of agricultural chemicals leads to the simultaneous presence of toxic substances. In this work, batch adsorption experiments were conducted to examine the biosorp-tion of HA onto chemically activated coffee husk. The biosorption process was studied as a function of operating conditions, such as contact time, pH of the solution, HA concentration, adsorbent dose and agitation speed parameters. Experimental results showed that the adsorption has an equilibrium time of 60 min with a maximum adsorption of 93.7%. The optimum pH for maximum HA adsorption was found to be 5.5, with a maximum adsorption of 94.3%.. As the dose of adsorbent increased from 1 to 25 g/L, the concentration of HA was observed to reduce from 10 to 1.67 mg/L which is below the WHO (World Health Organization) guideline value of 2 mg/L. The amount of HA adsorbed increased with increasing the initial adsorbent concentration from 0.5 to 20 mg/L. The adsorption kinet-ics well fitted the pseudo-second order model with the correlation coefficient R2 = 0.997 and Ks = 0.078. The experimental sorption equilibrium can be represented by the Langmuir isotherm (R2 = 0.998, SSE = 0.006). An average desorption capacity of 87.3% was observed. The study shows that chemically activated coffee husk can be a potential candidate to be used as a biosorbent in the removal of NOM from aqueous solutions. ABSTRACT AJCR: https://escipub.com/american-journal-of-chemical-research/ 1
Disinfection of swimming pools and hot tubs (pools/spas) are necessary to prevent outbreaks and exposure to waterborne pathogens from water recreation. However, harmful disinfection byproducts (DBPs) from heavy chlorine usage continue to be a growing concern. Chlorine-based disinfectants also react with human inputs like sweat, urine, cosmetics, sunscreen, etc., that are introduced in a pool/spa, further increasing the severity of the DBP problem. We reviewed the current status of water disinfection technologies in the pool/spa industry and summarize the methods, trends, advantages, and disadvantages from a health and consumer viewpoint. Market research and face-to-face interviews were also accomplished with 100 industry experts and end-users in the US. We then integrate the literature findings in parallel with these market insights. Overall, we conclude the future of water recreation is trending away from high dosage chlorine-based solutions to disinfect swimming water and turning to alternatives with better sustainability and safety in mind. Lastly, we discuss the future directions of these technologies with current and past trends, offering insights to where research and development should be focused for both the user’s health and overall experience.
The purpose of this chapter is to illustrate the impacts of climate change on environmental pollutants, chemical or biological pollutants, which are causing liver health problems. Liver diseases reflect broad disparities all over the world. The persistence of exposure to environmental chemical pollutants is proved to be affected by climate change stressors, such as variations in the atmospheric temperature and precipitation, sea level rise, and wind speeds and directions. An increase in temperature, as an example, may enhance the release, degradation, transportation, and mobilization of chemical pollutants. Wind speeds and directions affect mainly transportation, dispersion, and deposition of air pollutants that affect the burden of illness and mortality associated with them, and stagnation of the wind speed increases the concentration of pollutants. It was proved that global climate change has an impact on the biological pollutants through changing the distribution and movement of aquatic pollutants to higher latitudes, in addition to an increase in the growth of air biological microorganisms such as fungi with the increase in mycotoxin production. Therefore, climate changes have proved to have increased toxicity and bioaccumulation of the pollutants in the environment and in living creatures. The prediction of climate change impacts on the chemical and biological pollutants is still a formidable challenge for future science.
The control of disinfection byproducts (DBPs) in swimming pools is of great significance due to the non-negligible toxicity and widespread existence of DBPs. However, the management of DBPs remains challenging as the removal and regulation of DBPs is a multifactorial phenomenon in pools. This study summarized recent studies on the removal and regulation of DBPs, and further proposed some research needs. Specifically, the removal of DBPs was divided into the direct removal of the generated DBPs and the indirect removal by inhibiting DBP formation. Inhibiting DBP formation seems to be the more effective and economically practical strategy, which can be achieved mainly by reducing precursors, improving disinfection technology, and optimizing water quality parameters. Alternative disinfection technologies to chlorine disinfection have attracted increasing attention, while their applicability in pools requires further investigation. The regulation of DBPs was discussed in terms of improving the standards on DBPs and their preccursors. The development of online monitoring technology for DBPs is essential for implementing the standard. Overall, this study makes a significant contribution to the control of DBPs in pool water by updating the latest research advances and providing detailed perspectives.
Swimming pools adopt chlorination to ensure microbial safety. Giardia has attracted attention in swimming pool water because of its occurrence, pathogenicity, and chlorine resistance. To control Giardia concentrations in pool water and reduce the microbial risk, higher chlorine doses are required during disinfection. Unfortunately, this process produces carcinogenic disinfection byproducts that increase the risk of chemical exposure. Therefore, quantitatively evaluating the comparative microbial vs. chemical exposure risks that stem from chlorination inactivation of Giardia in swimming pool water is an issue that demands attention. We simulated an indoor swimming pool disinfection scenario that followed common real-world disinfection practices. A quantitative microbial risk assessment coupled with a chemical exposure risk assessment was employed to compare the Giardia microbial exposure risk (MER) and the trihalomethane chemical exposure risk (CER) to humans. The results demonstrated a 22% decrease in MER- and CER-induced health exposure risk, from 8.45E-5 at 8:00 to 6.60E-5 at 19:00. Both the MER and CER decreased gradually, dropping to 3.26E-5 and 3.35E-5 at 19:00, respectively. However, the CER exceeded the MER after 18:30 and became the dominant factor affecting the total exposure risk. Past the 18 h mark, the contribution of trihalomethane CER far exceeded the risk aversion from microbial inactivation, leading to a net increase in total exposure risk despite the declining MER. Swimmers may consider swimming after 19:00, when the total exposure risk is the lowest. Lowering water temperature and/or pH were identified as the most sensitive factors to minimize the overall health exposure risk.
Quantification of regulated and emerging disinfection byproducts (DBPs) in swimming pool water, as well as the assessment of their lifetime health risk are limited in China. In this study, the occurrence of regulated DBPs (e.g., trihalomethanes, haloacetic acids) and emerging DBPs (e.g., haloacetonitriles, haloacetaldehydes) in indoor swimming pool water and the corresponding source water at a city in Eastern China were determined. The concentrations of DBPs in swimming pool water were 1-2 orders of magnitude higher than that in source water. Lifetime cancer and non-cancer risks of DBPs stemming from swimming pool water were also estimated. Inhalation and dermal exposure were the most significant exposure routes related to swimming pool DBP cancer and non-cancer risks. For the first time, buccal and aural exposure were considered, and were proven to be important routes of DBP exposure (accounting for 17.9%-38.9% of total risk). The cancer risks of DBPs for all swimmers were higher than 10⁻⁶ of lifetime exposure risk recommended by United States Environmental Protection Agency, and the competitive adult swimmers experienced the highest cancer risk (7.82 × 10⁻⁵). These findings provide important information and perspectives for future efforts to lower the health risks associated with exposure to DBPs in swimming pool water.
This study aimed to estimate chronic daily intake (CDI) and to predict the attributable lifetime cancer risk (LCR) and hazard index (HI) from concurrent exposure to four trihalomethanes (THMs; chloroform, bromodichloromethane, dibromochloromethane and bromoform), via multiple exposure routes (oral ingestion, dermal contact and inhalation), among 238 non-competitive attendees of 10 Portuguese public indoor swimming pools (SPs), using a probabilistic approach based on Monte Carlo simulations. Exposure parameters of study participants were collected via questionnaires and THMs levels in SPs water were determined according the respective normative standards. The CDI for total THMs calculated for male and female participants considering all routes was 7.52 and 8.97 mg/kg/day, respectively. SP attendees presented higher CDI through inhalation than via the other two exposure routes, and chloroform was the compound contributing the most to total THMs CDI. The risk analysis indicated that the total LCR and HI from the targeted THMs were higher than the negligible risk levels (1 × 10⁻⁶ and 1, respectively) in the scenarios examined (central tendency exposure and reasonable maximum exposure), and the health risk for females was slightly higher than for males. This study suggests that there are possible adverse health risks, thus, to protect pool attendees, adequate mitigation measures, and comprehensive regulatory guidelines on individual THMs concentrations are needed.
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.
Chlorine is the most used chemical to disinfect water. Nevertheless, the reaction is not complete, and the remaining chlorine reacts with organic compounds present in the water leading to the formation of trihalomethanes. The legal limits for these compounds in drinking water vary from country to country, but guidelines from the European Union established 80 µg/L as the maximum accepted concentration. The objective of this review work was to analyze the Portuguese situation regarding trihalomethanes levels in the water, assess possible health risks and strategies to reduce their levels. Several epidemiological studies have reported an association between long-time exposure to higher trihalomethanes levels and cancer risk. Despite conflicting data, the stronger associations were for bladder, rectal and pancreatic cancer. One of the limitations of these studies is related to the difficulty in controlling confounding factors. In this sense, although the usual focus is trihalomethanes ingestion through drinking water, there are other forms of exposure, specifically dermic and inhalation. The first is particularly relevant during shower, due to the heated water, and the second when attending swimming pools. Other reported health problems due to trihalomethanes exposure include infertility and pregnancy complications, but these require additional research. In conclusion, many factors are still unknown regarding the impact of trihalomethanes on human health. Future investigations should take into consideration the cumulative exposure through different routes to obtain comprehensive and relevant conclusions.
In many countries water disinfection for human consumption is still carried out via chlorination which generates by-products such as trihalomethanes (THM). Exposure to THM constitutes a public health risk as such substances are known to be carcinogenic. This study evaluated exposure to THMs by inhalation in showers and assessed the carcinogenic risk for lifetime exposure. The study population involved students at Universidad de los Andes residing in Bogotá, Colombia. The risk assessment was performed stochastically and the exposure parameters were taken as probability distributions. Most variables were measured in relation to the chosen population. The risk was calculated using two different methodologies but no significant variations were obtained. The average risk calculated for men and women was 56 cases in a million (5.6 × 10⁻⁵). A sensitivity analysis was carried out where it was found that the parameters that increase risk the most are the concentration of chloroform in the water, exposure time, and the volume of the shower cubicle.
Disinfection means the killing of pathogenic organisms (e.g. bacteria and its spores, viruses, protozoa and their cysts, worms, and larvae) present in water to make it potable for other domestic works. The substances used in the disinfection of water are known as disinfectants. At municipal level, chlorine (Cl2), chloramines (NH2Cl, NHCl2), chlorine dioxide (ClO2), ozone (O3) and ultraviolet (UV) radiations, are the most commonly used disinfectants. Chlorination, because of its removal efficiency and cost effectiveness, has been widely used as method of disinfection of water. But, disinfection process may add several kinds of disinfection by-products (DBPs) (∼600-700 in numbers) in the treated water such as Trihalomethanes (THM), Haloacetic acids (HAA) etc. which are detrimental to the human beings in terms of cytotoxicity, mutagenicity, teratogenicity and carcinogenicity. In water, THMs and HAAs were observed in the range from 0.138-458 μg/L and 0.16-136 μg/L, respectively. Thus, several regulations have been specified by world authorities like WHO, USEPA and Bureau of Indian Standard to protect human health. Some techniques have also been developed to remove the DBPs as well as their precursors from the water. The popular techniques of DBPs removals are adsorption, advance oxidation process, coagulation, membrane based filtration, combined approaches etc. The efficiency of adsorption technique was found up to 90% for DBP removal from the water.
This study aimed to understand the exposure levels of trihalomethanes (THMs) in an indoor swimming pool and calculate the risks of exposure to THMs, based on the presence of each THM species, of children swimmers aged 6–17, in Beijing, China. We obtained exposure factors for the children through questionnaires and measured THM concentrations through laboratory tests, and we combined the results with an exposure model to calculate the risks, with consideration of different exposure routes (oral ingestion, inhalation and dermal absorption). In terms of exposure factors for the swimmers aged 6–17, the average body weight, exposure duration, exposure frequency, swimming time, shower time, changing time, warm-up exercise and rest time, skin surface area and ingestion rate of pool water were 40.46 kg, 2.70 years, 96 events/year, 64.03 min/event, 17.04 min/event, 15.31 min/event, 12.71 min/event, 1.37 m2 and 48.93 ml/event, respectively. The THM concentrations in swimming pool water, shower water, swimming pool air and locker room air were 67.17 μg/L, 12.64 μg/L, 358.66 μg/m3 and 40.98 μg/m3, respectively. The average cancer risk of THMs was 5.44 × 10−6, which is an unacceptable risk according to the United State Environmental Protection Agency(USEPA) Guidelines. The average hazard index was 0.007, i.e., less than 1, indicating that the noncancer risk was acceptable. TCM was the main substance in 4 species of THMs. and inhalation exposure was the main exposure pathway. The risk of cancer and noncancer from inhalation exposure to THMs accounts for 97%-99% of the total risk. As a result, the disease control authorities and administrative department should pay attention to the health and safety of swimming facilities and, at the same time, establish standards for THMs in the air through further research.
Taking samples at eight points chosen from two conventional water treatment plants for the city of Salamanca, the formation and evolution of THM levels were studied on 11 different dates. The values obtained were correlated statistically with the following parameters: concentration of humic acids (only raw water), pre- and postchlorination dosages, UV absorbance (UV-254), pH and temperature. No statistical correlation was observed either with the humic acids content or with the organic matter measured as UV-254. A correlation was only found with the prechlorination dosage in the clarifiers of the old plant. However, in both plants there was a correlation with the postchlorination dosage although this was not very patent owing to the impossibility of knowing the contribution of each parameter at one of the sampling sites where postchlorination and pH correction are performed simultaneously. A clear linear correlation (r = 0.4345, P = 0.0001) was observed with temperature. Using stepwise regression (ANCOVA) a mathematical function was obtained (R = 0.8066, P = 0.0001) that relates the concentration of chloroform with temperature and the sampling points. From this it is deduced that both pH and temperature increase this concentration, although for each pH value all the In CHCl3 (μg/l) vs temperature curves showed a maximum (Tc = 18.97°C), after which chloroform levels decrease sharply. On attempting to quantify the contribution of the rest of the parameters studied here concerning the levels of THMs, it may be inferred that others should be considered, such as the design, the dimensions and the exploitation of the water treatment plants studied.
Ozone has been proposed for water disinfection because it is more efficient than chlorine for killing microbes and results in much lower levels of carcinogenic trihalomethanes than does chlorination. Ozone leads to formation of hypobromous acid in surface waters with high bromine content and forms brominated organic by-products and bromate. The carcinogenicity and chronic toxicity of potassium bromate (KBrO3) was studied in male B6C3F1 mice and F344/N rats to confirm and extend the results of previous work. Mice were treated with 0, 0.08, 0.4, or 0.8 g/L KBrO3 in the drinking water for up to 100 wk, and rats were provided with 0, 0.02, 0.1, 0.2, or 0.4 g/L KBrO3. Animals were euthanatized, necropsied, and subjected to a complete macroscopic examination. Selected tissues and gross lesions were processed by routine methods for light microscopic examination. The present study showed that KBrO3 is carcinogenic in the rat kidney, thyroid, and mesothelium and is a renal carcinogen in the male mouse, KBrO3 was carcinogenic in rodents at water concentrations as low as 0.02 g/L (20 ppm; 1.5 mg/kg/day). These data can be used to estimate the human health risk that would be associated with changing from chlorination to ozonation for disinfection of drinking water.
Exposure to drinking water disinfection by-products (DBPs), such as trihalomethanes (THMs), has been associated with bladder and colorectal cancer in humans. Exposure to DBPs has typically been determined by examining historical water treatment records and reconstructing study participants' water consumption histories. However, other exposure routes, such as dermal absorption and inhalation, may be important components of an individual's total exposure to drinking water DBPs. In this study, we examined individuals' exposure to THMs through drinking, showering, or bathing in tap water. Thirty-one adult volunteers showered with tap water for 10 min (n = 11), bathed for 10 min in a bathtub filled with tap water (n = 10), or drank 1 l of tap water during a 10 min time period (n = 10). Participants provided three 10 ml blood samples: one sample immediately before the exposure; one sample 10 min after the exposure ended; and one sample 30 min (for shower and tub exposure) or 1 h ( for ingestion) after the exposure ended. A sample of the water (from the tap, from the bath, or from the shower) was collected for each participant. We analyzed water samples and whole blood for THMs (bromoform, bromodichloromethane, dibromochloromethane, and chloroform) using a purge-and-trap/gas chromatography/mass spectrometry method with detection limits in the parts-per-quadrillion range. The highest levels of THMs were found in the blood samples from people who took 10 min showers, whereas the lowest levels were found in the blood samples from people who drank 1 l of water in 10 min. The results from this study indicate that household activities such as bathing and showering are important routes for human exposure to THMs.
Samples of drinking water are routinely analysed for four trihalomethanes (THMs), which are indicators of by-products of disinfection with chlorine, by UK water suppliers to demonstrate compliance with regulations. The THM data for 1992-1993 to 1997-1998 for three water suppliers in the north and midlands of England were made available for a UK epidemiological study of the association between disinfection by-products and adverse birth outcomes. This paper describes the THM levels in these three supply regions and discusses possible sources of variation. THM levels varied between different suppliers' water, and average THM levels were within the regulatory limits. Chloroform was the predominant THM in all water types apart from the ground water of one supplier. The supplier that distributed more ground and lowland surface water had higher dibromochloromethane (DBCM) and bromoform levels and lower chloroform levels than the other two suppliers. In the water of two suppliers, seasonal fluctuations in bromodichloromethane (BDCM) and DBCM levels were found with levels peaking in the summer and autumn. In the other water supplier, chloroform levels followed a similar seasonal trend whereas BDCM and DBCM levels did not. For all three water suppliers, chloroform levels declined throughout 1995 when there was a drought period. There was a moderate positive correlation between the THMs most similar in their structure (chloroform and BDCM, BDCM and DBCM, and DBCM and bromoform) and a slight negative correlation between chloroform and bromoform levels.
The occurrence and the fate of trihalomethanes (THMs) in the water supply system of Hanoi City, Vietnam was investigated from 1998 to 2001. The chlorination efficiency, THM speciation, and, THM formation potential (THMFP) was determined in the water works and in tap water. With regard to THM formation, three types of groundwater resources were identified: (I) high bromide, (II) low bromide, and (III) high bromide combined with high ammonia and high dissolved organic carbon (DOC) concentrations. Under typical treatment conditions (total chlorine residual 0.5-0.8 mg/L), the total THM formation was always below WHO, EU, and USEPA drinking water standards and decreased in the order type I > type II > type III, although the THMFP was > 400 micrograms/L for type III water. The speciation showed > 80% of bromo-THMs in type I water due to the noticeable high bromide level (< or = 140 micrograms/L). In type II water, the bromo-THMs still accounted for some 40% although the bromide concentration is significantly lower (< or = 30 micrograms/L). In contrast, only traces of bromo-THMs were formed (approximately 5%) in type III water, despite bromide levels were high (< or = 240 micrograms/L). This observation could be explained by competition kinetics of chlorine reacting with ammonia and bromide. Based on chlorine exposure (CT) estimations, it was concluded that the current chlorination practice for type I and II waters is sufficient for > or = 2-log inactivation of Giardia lamblia cysts. However, in type III water the applied chlorine is masked as chloramine with a much lower disinfection efficiency. In addition to high levels of ammonia, type III groundwater is also contaminated by arsenic that is not satisfactory removed during treatment. N-nitrosodimethylamine, a potential carcinogen suspected to be formed during chloramination processes, was below the detection limit of 0.02 microgram/L in type III water.
Dermal contact with some organic disinfection by-products (DBPs) such as trihalomethanes in chlorinated drinking water has been established to be an important exposure route. We evaluated dermal absorption of two haloketones (1,1-dichloropropanone and 1,1,1-trichloropropanone) and chloroform while bathing, by collecting and analyzing time profiles of expired breath samples of six human subjects during and following a 30-min bath. The DBP concentrations in breath increased towards a maximum concentration during bathing. The maximum haloketone breath concentration during dermal exposure ranged from 0.1 to 0.9 microg / m(3), which was approximately two orders of magnitude lower than the maximum chloroform breath concentration during exposure. Based on a one-compartment model, the in vivo permeability of chloroform, 1,1-dichloropropanone, and 1,1,1-trichloropropanone were approximated to be 0.015, 7.5 x 10(- 4), and 4.5 x 10(- 4) cm / h, respectively. Thus, haloketones are much less permeable across human skin under normal bathing conditions than is chloroform. These findings will be useful for future assessment of total human exposure and consequent health risk of these DBPs.
Cryptosporidium parvum oocysts and Clostridium perfringens spores are very resistant to chlorine and other drinking-water disinfectants. Clostridium perfringens spores have been suggested as a surrogate indicator of disinfectant activity against Cryptosporidium parvum and other hardy pathogens in water. In this study, an alternative disinfection system consisting of an electrochemically produced mixed-oxidant solution (MIOX; LATA Inc.) was evaluated for inactivation of both Cryptosporidium parvum oocysts and Clostridium perfringens spores. The disinfection efficacy of the mixed-oxidant solution was compared to that of free chlorine on the basis of equal weight per volume concentrations of total oxidants. Batch inactivation experiments were done on purified oocysts and spores in buffered, oxidant demand-free water at pH 7 and 25°C by using a disinfectant dose of 5 mg/liter and contact times of up to 24 h. The mixed-oxidant solution was considerably mute effective than free chlorine in inactivating both microorganisms. A 5-mg/liter dose of mixed oxidants produced a >3-log10- unit (>99.9%) inactivation of Cryptosporidium parvum oocysts and Clostridium perfringens spores in 4 h. Free chlorine produced no measurable inactivation of Cryptosporidium parvum oocysts by 4 or 24 h, although Clostridium perfringens spores were inactivated by 1.4 log10 units after 4 h. The on- site generation of mixed oxidants may be a practical and cost-effective system of drinking water disinfection protecting against even the most resistant pathogens, including Cryptosporidium oocysts.
Bladder cancer has been associated with exposure to chlorination by-products in drinking water, and experimental evidence suggests that exposure also occurs through inhalation and dermal absorption. The authors examined whether bladder cancer risk was associated with exposure to trihalomethanes (THMs) through ingestion of water and through inhalation and dermal absorption during showering, bathing, and swimming in pools. Lifetime personal information on water consumption and water-related habits was collected for 1,219 cases and 1,271 controls in a 1998-2001 case-control study in Spain and was linked with THM levels in geographic study areas. Long-term THM exposure was associated with a twofold bladder cancer risk, with an odds ratio of 2.10 (95% confidence interval: 1.09, 4.02) for average household THM levels of >49 versus < or =8 micro g/liter. Compared with subjects not drinking chlorinated water, subjects with THM exposure of >35 micro g/day through ingestion had an odds ratio of 1.35 (95% confidence interval: 0.92, 1.99). The odds ratio for duration of shower or bath weighted by residential THM level was 1.83 (95% confidence interval: 1.17, 2.87) for the highest compared with the lowest quartile. Swimming in pools was associated with an odds ratio of 1.57 (95% confidence interval: 1.18, 2.09). Bladder cancer risk was associated with long-term exposure to THMs in chlorinated water at levels regularly occurring in industrialized countries.
Cryptosporidium parvum oocysts and Clostridium perfringens spores are very resistant to chlorine and other drinking-water disinfectants. Clostridium perfringens spores have been suggested as a surrogate indicator of disinfectant activity against Cryptosporidium parvum and other hardy pathogens in water. In this study, an alternative disinfectant system consisting of an electrochemically produced mixed-oxidant solution (MIOX; LATA Inc.) was evaluated for inactivation of both Cryptosporidium parvum oocysts and Clostridium perfringens spores. The disinfection efficacy of the mixed-oxidant solution was compared to that of free chlorine on the basis of equal weight per volume concentrations of total oxidants. Batch inactivation experiments were done on purified oocysts and spores in buffered, oxidant demand-free water at pH 7 an 25 degrees C by using a disinfectant dose of 5 mg/liter and contact times of up to 24 h. The mixed-oxidant solution was considerably more effective than free chlorine in activating both microorganisms. A 5-mg/liter dose of mixed oxidants produced a > 3-log10-unit (> 99.9%) inactivation of Cryptosporidium parvum oocysts and Clostridium perfringens spores in 4 h. Free chlorine produce no measurable inactivation of Cryptosporidium parvum oocysts by 4 or 24 h, although Clostridium perfringens spores were inactivated by 1.4 log10 units after 4 h. The on-site generation of mixed oxidants may be a practical and cost-effective system of drinking water disinfection protecting against even the most resistant pathogens, including Cryptosporidium oocysts.
Chloroform, generally regarded as a non-genotoxic compound, is associated with the induction of liver and/or kidney tumors in laboratory mice and rats. In particular, chloroform produced renal tubule tumors in low incidence in male Osborne-Mendel rats when administered by corn-oil gavage or in the drinking water. There is a lack of data on intermediate endpoints that may be linked to renal cancer development in this strain of rat, in contrast to mice. Specifically, evidence linking chloroform-induced liver and kidney tumors in mice with cytotoxicity and regenerative cell proliferation is very strong, but weak in the rat. In the present study, kidney tissue from a carcinogenicity bioassay of chloroform in Osborne-Mendel rats was re-evaluated for histological evidence of compound-induced cytotoxicity and cell turnover. All rats treated with 1800 ppm (160 mg/kg/day, high-dose group) in the drinking water for 2 years and half the rats treated with 900 ppm (81 mg/kg/day) had mild to moderate changes in proximal convoluted tubules in the mid to deep cortex indicative of chronic cytotoxicity. Tubule alterations specifically associated with chronic chloroform exposure included cytoplasmic basophilia, cytoplasmic vacuolation, and nuclear crowding consistent with simple tubule hyperplasia. Occasional pyknotic cells, mitotic figures in proximal tubules, and prominent karyomegaly of the renal tubule epithelium were present. These alterations were not present in control groups or at the 200-ppm (19 mg/kg/day) or 400-ppm (38 mg/kg/day) dose levels. This new information adds substantially to the weight of evidence that the key events in chloroform-induced carcinogenicity in rat kidney include sustained cellular toxicity and chronic regenerative hyperplasia.
The formation of trihalomethanes (THMs) in a model swimming pool using hypobromous and hypochlorous acids as disinfectants has been studied. Factorial design was used to generate and process data from systematically-conducted experiments on a series of 11 samples of swimming pool simulant. The variables considered were organic loading (urine and humic acid concentration), disinfectant type and concentration, incubation time and degree of agitation. A disinfectant concentration of 6 mg l−1 was used throughout. The variables affecting bromoform formation were urine and humic acid concentration and disinfectant type. Interactions were observed between humic acid and urine and also between urine and disinfectant. The effect of urine was to suppress bromoform formation. Levels of chlorine-containing THMs were unaffected by humic acid at the concentrations used; only the urine concentration and disinfectant type had a significant effect on these THMs. No interactions between any three or more variables were observed for any THM.
Using a combination of spectral identification techniquesgas chromatography coupled with low- and high-resolution electron-impact mass spectrometry (GC/EI-MS), low- and high-resolution chemical ionization mass spectrometry (GC/CI-MS), and infrared spectroscopy (GC/IR)we identified many drinking water disinfection byproducts (DBPs) formed by ozone and combinations of ozone with chlorine and chloramine. Many of these DBPs have not been previously reported. In addition to conventional XAD resin extraction, both pentafluorobenzylhydroxylamine (PFBHA) and methylation derivatizations were used to aid in identifying some of the more polar DBPs. Many of the byproducts identified were not present in spectral library databases. The vast majority of the ozone DBPs identified contained oxygen in their structures, with no halogenated DBPs observed except when chlorine or chloramine was applied as a secondary disinfectant. In comparing byproducts formed by secondary treatment of chlorine or chloramine, chloramine appeared to form the same types of halogenated DBPs as chlorine, but they were generally fewer in number and lower in concentration. Most of the halogenated DBPs that were formed by ozone−chlorine and ozone−chloramine treatments were also observed in samples treated with chlorine or chloramine only. A few DBPs, however, were formed at higher levels in the ozone−chlorine and ozone−chloramine samples, indicating that the combination of ozone and chlorine or chloramine is important in their formation. These DBPs included dichloroacetaldehyde and 1,1-dichloropropanone.
In general, chlorination is the method of drinking water disinfection most favoured by the water industry. Occasional outbreaks of water transmitted disease, the identification of chlorine as a source of potentially harmful disinfection by-products, and the emergence of recalcitrant pathogens has led to heightened regulation for the removal of microbial pathogens and disinfection by-products from drinking water. As a result, research and development of alternative disinfection technologies has intensified. Electrochemical disinfection has emerged as one of the more feasible alternatives to chlorination. Research using a range of cell configurations has shown electrochemical disinfection to be effective against a range of pathogens. However, in many of the systems, disinfection efficacy appears to be related to the generation of chlorine species. The apparent prevalence of chlorine as the mechanism of disinfection begs the question as to whether electrochemical disinfection has an advantage over chlorination in terms of its inactivation efficacy and potential to form disinfection by-products. This paper reports on a series of experiments evaluating the disinfection efficacy of an electrochemical disinfection technology against Escherichia coli and bacteriophage MS2. The results of these experiments conclude that electrochemical disinfection can be effective without the generation of chlorine species.
Natural water, highly contaminated with coliforms, was electrochemically treated in a stirred batch system with the use of two Ti electrodes and direct current, the polarity of which alternated automatically in half cycles of 1 min. The process was found to be effective and the percentage of the initial concentration of bacteria which were destroyed was found to be proportional to both treatment time and the square of current density obeying the kinetic model α = ki2 t; consequently the time needed for complete disinfection was inversely proportional to the square of current density. The percentage above was found to be independent of the initial concentration of germs at least for the range of concentrations employed. The residual disinfection capacity, after completion of the electrochemical treatment, was also verified by mixing electrochemically treated, disinfected natural water with contaminated water.
Water from swimming pools in the Miami area was analyzed for nitrates, chlorates and trihalomethanes. The average concentrations of nitrate and chlorate found in freshwater pools were 8.6 mg/liter and 16 mg/liter respectively, with the highest concentrations being 54.9 mg/liter and 124 mg/liter, respectively. The average concentration of total trihalomethanes found in freshwater pools was 125 micrograms/liter (mainly chloroform) and in saline pools was 657 micrograms/liter (mainly bromoform); the highest concentration was 430 micrograms/liter (freshwater) and 1287 micrograms/liter (saltwater). The possible public health significance of these results is briefly discussed.
The presence of chloroform as the result of disinfection with sodium hypochlorite was demonstrated in the water and ambient air of indoor swimming pools. Environmental monitoring was performed in 12 indoor swimming pools in northern Italy and the level of human exposure was assessed. Biological monitoring performed by gas chromatography on human plasma and alveolar air samples evidenced that the uptake of chloroform in swimmers varies according to the intensity of the physical activity and age. The elimination of chloroform in alveolar air in one subject showed a very short half-life (from 20 to 27 min) and a complete clearance within 10 h after the end of exposure.
In this article, exposure to trihalomethanes (THMs) in indoor swimming pools as a consequence of water chlorination is reported. Environmental and biological monitoring of THMs was performed in order to assess the uptake of these substances after a defined period in five competitive swimmers, regularly attending an indoor swimming pool to train for competition during four sampling sessions. Analyses were performed by gas-chromatography and the following THMs were detected: chloroform (CHC13), bromodichloromethane (CHBrC12), dibromochloromethane (CHBrsC1) and bromoform (CHBr3). CHC13 appeared the most represented compound both in water and in environmental air before and after swimming. CHBrC1w and CHBr2C1 were always present, even though at lower levels than CHC13, CHBr3, was rarely present. In relation to biological monitoring, CHC13, CHBrC12 and CHBr2C1 were detected in all alveolar air samples collected inside the swimming pool. Before swimming, after 1 h at rest at the pool edge, the mean values were 29.4 +/- 13.3, 2.7 +/- 1.2 and 0.8 +/- 0.8 micrograms/m3, respectively, while after spending 1 h swimming, higher levels were detected (75.6 +/- 18.6, 6.5 +/- 1.3 and 1.4 +/- 0.9 micrograms/m3, respectively). Only CHC13 was detected in all plasma samples (mean: 1.4 +/- 0.5 micrograms/1) while CHBrC1x and CHBr2C1 were observed only in few samples at a detection limit of 0.1 micrograms/1. After 1 h at rest, at an average environmental exposure of approx. 100 micrograms/m3, the THM uptake was approx. 30 micrograms/h (26 micrograms/h for CHC1c, 3 micrograms/h for CHBrC12 and 1.5 micrograms/h for CHBr2C1). After 1 h swimming, the THM uptake is approx. seven times higher than at rest: a THM mean uptake of 221 micrograms/h (177 micrograms/h, 26 micrograms/h and 18 micrograms/h for CHC13, CHBrC12 and CHBr2C1, respectively) was evaluated at an environmental concentration of approx. 200 micrograms/m3.
Chloroform, generally regarded as a non-genotoxic compound, is associated with the induction of liver and/or kidney tumors in laboratory mice and rats. In particular, chloroform produced renal tubule tumors in low incidence in male Osborne-Mendel rats when administered by corn-oil gavage or in the drinking water. There is a lack of data on intermediate endpoints that may be linked to renal cancer development in this strain of rat, in contrast to mice. Specifically, evidence linking chloroform-induced liver and kidney tumors in mice with cytotoxicity and regenerative cell proliferation is very strong, but weak in the rat. In the present study, kidney tissue from a carcinogenicity bioassay of chloroform in Osborne-Mendel rats was re-evaluated for histological evidence of compound-induced cytotoxicity and cell turnover. All rats treated with 1800 ppm (160 mg/kg/day, high-dose group) in the drinking water for 2 years and half the rats treated with 900 ppm (81 mg/kg/day) had mild to moderate changes in proximal convoluted tubules in the mid to deep cortex indicative of chronic cytotoxicity. Tubule alterations specifically associated with chronic chloroform exposure included cytoplasmic basophilia, cytoplasmic vacuolation, and nuclear crowding consistent with simple tubule hyperplasia. Occasional pyknotic cells, mitotic figures in proximal tubules, and prominent karyomegaly of the renal tubule epithelium were present. These alterations were not present in control groups or at the 200-ppm (19 mg/kg/day) or 400-ppm (38 mg/kg/day) dose levels. This new information adds substantially to the weight of evidence that the key events in chloroform-induced carcinogenicity in rat kidney include sustained cellular toxicity and chronic regenerative hyperplasia.
Pre-oxidation is often applied to reduce the formation of disinfection by-products (DBPs). The aim of pre-oxidation is to remove the centers of natural organic matter (NOM) which are responsible for the formation of DBPs. In this paper, the differences between ozone- and OH-radical-induced oxidation to remove DBP-precursors are compared. The experiments were done with water of the River Ruhr (Germany) with a concentration of dissolved organic carbon (DOC) of 2 mg/l. Ozonation was able to remove DBP precursors selectively. After application of an absorbed ozone mass of 1.5 mg/mg DOC, a reduction in the formation potential for (THM-FP) and in the formation potential for organic halogen adsorbable on activated carbon (AOX-FP) down to 68 and 73% of the initial concentration was achieved, respectively. A removal of NOM was not achieved using absorbed ozone masses between 0.5 and 1.5 mg/mg DOC. In the hydrogen peroxide/UV process, in which OH-radicals are the reactive species, an increase in the THM concentration was measured after application of this process with short irradiation times. The maximum value of the THM-FP was 20% higher than the initial THM-FP. After an irradiation time of 1,050 min and a hydrogen peroxide consumption of 5.6 mg/l, the THM-FP and AOX-FP decreased to 75 and 71% of the initial formation potential, respectively. There was no selective removal of DBP precursors because the DOC concentration decreased also to 75% of the initial DOC-concentration after 1,050 min of irradiation.
This population-based case-control study was conducted in southern Ontario, Canada from 1992 to 1994 to assess the relationship between chlorination by-products in public water supplies and cancers of the colon and rectum. Interviews providing residence and water source histories were completed by 76% of eligible cancer cases and 72% of eligible controls. Supplemental data from municipal water supplies were used to estimate individual exposure to water source, chlorination status, and by-product levels as represented by trihalomethanes (THMs) during the 40-year period before the interview. The analyses included 767 colon cases, 661 rectal cases, and 1545 controls with exposure information for at least 30 of these years (75% of subjects with completed interviews). Among males, colon cancer risk was associated with cumulative exposure to THMs, duration of exposure to chlorinated surface water, and duration of exposure to a THM level > or = 50 microg/liter and 75 microg/liter. Males exposed to chlorinated surface water for 35-40 years had an increased risk of colon cancer compared with those exposed for < 10 years (odds ratio, 1.53; 95% confidence interval, 1.13-2.09). Males exposed to an estimated THM level of 75 microg/liter for > or = 35 years had double the risk of those exposed for < 10 years (odds ratio, 2.10; 95% confidence interval, 1.21-3.66). In contrast, these relationships were not observed among females. No relationship was observed between rectal cancer risk and any of the measures of exposure to chlorination by-products. The results of this study should be interpreted with caution because they are only partially congruent with the limited amount of literature addressing this issue.
We have reviewed the relevant issues in the exposure assessment of disinfection by-products (DBPs) of chlorination for epidemiological and health risk assessment. Various DBPs can be detected in drinking water and swimming pools, and the reported levels show a considerable range, but were generally below the current health standard for total trihalomethanes (TTHMs) (100 microg/l). Relatively little information is available on the correlation between the various DBPs in drinking water and in swimming pools. Chloroform was generally, but not always, the most predominant DBP. In epidemiological studies, TTHM levels have been used as an indicator for total DBP load, even though TTHM levels do not always correlate well with individual DPBs. Factors such as residence time, temperature, pH, organic content, including humic and fulvic acid and bromide levels affect the composition and levels of DBPs. Although there are biomarkers of DBPs, mainly for chloroform and more recently for the other volatile trihalomethanes (THMs) and the nonvolatile haloacetic acids (HAAs) such as trichloroacetic acid (TCAA) and dichloroacetic acid (DCAA), they have not been used in epidemiological studies. The THMs have been measured in exhaled breath and serum, while the HAAs have been measured in urine. These biomarkers have been useful to estimate the actual uptake of the DBPs and the relative contribution of various exposure routes. Physiologically based pharmacokinetic (PBPK) models exist for, e.g. chloroform, but their main target organs are the kidney and liver and they have not been used in epidemiological studies. Tap water ingestion, showering, bathing, swimming, boiling water and dishwashing are all activities that have been associated with the uptake of DBPs, and considerable variation in these activities has been observed between people. No studies have reported on the correlation between human uptake of DBPs and water-zone mean estimates, but various studies found a good correlation between THM concentrations in exhaled breath and THM concentrations in water during showering and swimming. In general exposure assessment in epidemiological studies has been limited which complicates the interpretation. These findings have implications for epidemiological studies, particularly with reference to Berkson and classical error type models, study power, attenuation and precision of health-risk estimates and study efficiency. Recommendations are made for further areas of study.
Data on concentrations of trihalomethanes (THMs) in raw and chlorinated water collected from three water treatment plants in Taiwan and estimates of the lifetime cancer risk for THMs from drinking water, using age-adjusted factors and volatilization terms, are presented. Data on THM levels in drinking water were obtained from the annual reports of the Environmental Protection Administration (EPA) of Taiwan. The methodology for estimation of lifetime cancer risks was taken from the USEPA. Chloroform was the major species of THMs, especially in the water plant of south Taiwan. Chloroform contributed the majority of the lifetime cancer risks (range: 87.5-92.5%) of total risks from the three water supply areas. All lifetime cancer risks for CHCl(3), CHBrCl(2), CHBr2Cl, and CHBr3 from consuming tap water in the three water supply areas were higher than 10(-6). The sum of lifetime cancer risks for CHCl(3), CHBrCl(3), CHBr2Cl, and CHBr3 was highest (total risk for total THMs<1.94x10(-4)) for tap water from south Taiwan.
The study evaluated occupational exposure to trihalomethanes (THMs) in indoor swimming pools. Thirty-two subjects, representing the whole workforce employed in the five public indoor swimming pools in the city of Modena (Northern Italy) were enrolled. Both environmental and biological monitoring of THMs exposure were performed. Environmental concentrations of THMs in different areas inside the swimming pools (at the poolside, in the reception area and in the engine-room) were measured as external exposure index, while individual exposure of swimming pool employees was estimated by THMs concentration in alveolar air. The levels of THMs observed in swimming pool water ranged from 17.8 to 70.8 microg/l; the mean levels of THMs in ambient air were 25.6+/-24.5 microg/m3 in the engine room, 26.1+/-24.3 microg/m3 in the reception area and 58.0+/-22.1 microg/m3 at the poolside. Among THMs, only chloroform and bromodichloromethane were always measured in ambient air, while dibromochloromethane was detected in ambient air rarely and bromoform only once. Biological monitoring results showed a THMs mean value of 20.9+/-15.6 microg/m3. Statistically significant differences were observed according to the main job activity: in pool attendants, THMs alveolar air were approximately double those observed in employees working in other areas of the swimming pools (25.1+/-16.5 microg/m3 vs. 14.8+/-12.3 microg/m3, P < 0.01). THMs in alveolar air samples were significantly correlated with THMs concentrations in ambient air (r = 0.57; P < 0.001). Indoor swimming pool employees are exposed to THMs at ambient air levels higher than the general population. The different environmental exposure inside the swimming pool can induce a different internal dose in exposed workers. The correlation found between ambient and alveolar air samples confirms that breath analysis is a good biological index of occupational exposure to these substances at low environmental levels.
The effect of ultraviolet radiation from low- and medium-pressure mercury arc lamps on Cryptosporidium parvum oocysts was studied using a collimated beam apparatus. Experiments were conducted using parasites suspended in both filtered surface water and phosphate buffered laboratory water. Inactivation of oocysts was measured as reduction in infectivity using a CD-1 neonatal mouse model and was found to be a non-linear function of UV dose over the range of germicidal doses tested (0.8-119 mJ/cm2). Oocyst inactivation increased rapidly with UV dose at doses less than 25 mJ/cm2 with two and three log-units inactivation at approximately 10 and 25 mJ/cm2, respectively. The cause of significant leveling-off and tailing in the UV inactivation curve at higher doses was not determined. Maximum measured oocyst inactivation ranged from 3.4 to greater than 4.9 log-units and was dependent on different batches of parasites. Water type and temperature, the concentration of oocysts in the suspension, and the UV irradiance did not have significant impacts on oocyst inactivation. When compared on the basis of germicidal UV dose, the oocysts were equally sensitive to low- and medium-pressure UV radiation. With respect to Cryptosporidium, both low- and medium-pressure ultraviolet radiation are attractive alternatives to conventional chemical disinfection methods in drinking water treatment.
In drinking water treatment, the inactivation of microorganisms increases with increasing disinfectant exposure (product of concentration and contact time, CT). Also, the formation of undesired (toxic) disinfection by-products increases with CT. The present study proposes a new concept that uses this undesired side effect of chemical water disinfection for a fast and reliable test of treatment efficiency. In laboratory systems, bromate formation during ozonation and the formation of trihalomethanes during chlorination were used to calculate the disinfectant exposure, which is a measure for the achieved degree of disinfection.
Fifteen chlorination by-products were analyzed in 416 water samples collected from 35 water treatment plants in Korea from 1996 to 1998. These samples were divided into five groups according to water sources (Han-river, Nakdong-river, Youngsan-river, Kum-river and Cheju) and detected CBPs were classified into six classes (trihalomethanes; THMs, haloacetic acids; HAAs, haloacetonitriles: HANs haloketones; HKs, chloralhydrate; CH, chloropicrin; CP) and then, it was observed the detection tendency and frequency of CBPs in each water source. The total concentration of CBPs in treated water from Nakdong-river or Han-river was higher than those from the other rivers. And the distribution pattern of each class of CBPs was similar in all water sources. THMs were the highest portion in the range of 40-50%, and HAAs and HANs were 28-35 and 9-15%, respectively. And there was a strong correlation between HANs and HKs (r=0.813). Each and total concentrations of CBPs showed to be more affected by the water source in two-way analysis of variance (two-way ANOVA) among the concentration of CBPs, the source of water and season.
The formation of five volatile disinfection by-products (DBPs: chloroform, bromodichloromethane, chloral hydrate, dichloroacetonitrile, and 1,1,1-trichloropropanone) by the chlorination of the materials of human origin (MHOs: hair, lotion, saliva, skin, and urine) in a swimming pool model system was examined. Chlorination reactions took place with a sufficient supply of chlorine residuals (0.84 mg Cl2/l < total chlorine < 6.0 mg Cl2/l) in 300 ml glass bottles containing either ground water or surface water as a reaction medium at 30 degrees C and pH 7.0, for either 24 or 72 h. A longer reaction period of 72 h or a higher content of organic materials led to the increased formation of DBPs. Of the DBPs formed by the reaction, chloroform was a major compound found in both ground and surface waters. The formation of chloroform and bromodichloromethane per unit total organic carbon (TOC) concentration was suppressed when all types of MHOs were added to the surface water that already contained DBP precursors such as humic substances. However, the formation of dichloroacetonitrile was promoted, probably due to the increased degradation reactions of nitrogen-containing compounds such as urea and proteins of human origin. In conclusion, the materials of swimmers' origin including hair, lotion, saliva, skin, and urine add to the levels of DBPs in swimming pool water, and any mitigation measures such as periodic change of water are needed to protect swimmers from elevated exposures to these compounds.
For many decades chlorination has been used as a major disinfectant process for public drinking and swimming pool water in many countries. However, there has been rising concern over the possible link between disinfectant byproducts (DBPs) and adverse reproductive outcomes. The purpose of this study was to estimate the concentrations of trihalomethanes (THMs) in some indoor swimming pools in London and their variation within and between pools and any correlation with other factors.
Water samples were collected from eight different indoor swimming pools in London. A total of 44 pool samples were collected and analysed for total organic content (TOC) and THMs. Water and air temperature were measured along with the pH during the collection of pool samples. The level of turbulence and the number of people in the pool at the time were also assessed.
The geometric mean concentration for all swimming pools of TOC was 5.8 mg/l, of total THMs (TTHMs) 132.4 microg/l, and for chloroform 113.3 microg/l. There was a clear positive linear correlation between the number of people in the swimming pool and concentrations of TTHMs and chloroform (r=0.7, p<0.01), and a good correlation between concentrations of TOC and TTHMs (r=0.5, p<0.05) and water temperature and concentrations of TTHMs (r=0.5, p<0.01). There was a larger variation in THMs within pools than between pools.
Relatively high concentrations of THMs were found in London's indoor swimming pools. The levels correlated with the number of people in the pool, water temperature, and TOC. The variation in concentrations of THMs was greater within pools than between pools.
A life-time exposure study was conducted to assess the carcinogenicity of bromodichloromethane (BDCM) administered in the drinking water to male F344/N rats and B6C3F(1) mice. In mouse, the calculated mean daily BDCM concentrations (measured concentrations corrected for on-cage loss of chemical) were 0.06, 0.28 and 0.49 g/l. Time-weighted water consumption of 135, 97, and 89 ml/kg/day resulted in mean daily doses of 8.1, 27.2, and 43.4 mg BDCM/kg/day. No changes in feed consumption, final body weight, or survival were observed. Kidney weights were significantly depressed at 27.2 and 43.4 mg BDCM/kg/day. There was no increase in neoplasia in the liver, kidney, spleen, testis, bladder, sections along the alimentary tract, excised lesions, or at any other organ site. In rat, the corrected mean daily BDCM concentrations were 0.06, 0.33, and 0.62 g/l. Time-weighted water consumption of 65, 63, and 59 ml/kg/day yielded 3.9, 20.6 and 36.3 mg BDCM/kg/day. No alterations in feed consumption, body weight gain, and survival were seen. Kidney weight was significantly depressed in the 36.3-mg/kg/day treatment group. There was a significantly enhanced prevalence and multiplicity of hepatocellular adenomas at 3.9 mg BDCM/kg/day (15.5% and 0.16/animal vs. 2.2% and 0.02/animal for the control). Hepatocellular carcinomas increased from 2.2% and 0.02/animal for the control and 3.9 mg BDCM/kg/day to 8.3% and 0.10/animal at 20.6 mg BDCM/kg/day. The combined neoplasms were enhanced at 3.9 and 20.6 mg BDCM/kg/day. Liver neoplasia was depressed to the control value at 36.3 mg BDCM/kg. The prevalence of basophilic and clear cell, but not eosinophilic cells, altered foci of cells declined with increasing dose. BDCM did not increase cancer in the large bowel, renal tubules, or in any of the other tissues examined. Renal tubular hyperplasia was observed at 36.3 mg BDCM/kg (15.8% vs. 8.7% for the control group). Under the conditions of the study, BDCM in the drinking water was not carcinogenic in the male B6C3F(1) mouse, but was carcinogenic in the male F344/N rat based on an increased hepatocellular neoplasia.
Electric fields and currents have been shown to be capable of disinfecting drinking water and reducing the numbers of bacteria and yeast in food. However, little research has been conducted regarding the effectiveness of electric fields and currents in the inactivation of viruses. The objective of this study was to compare the ability of bacteria and bacteriophage to survive exposure to direct electric current in an electrochemical cell, where they would be subject to irreversible membrane permeabilization processes, direct oxidation of cellular/viral constituents by electric current, and disinfection by electrochemically generated oxidants. Suspensions of the bacteria Escherichia coli and Pseudomonas aeruginosa and bacteriophage MS2 and PRD1 at both high (approximately 1 x 10(6)CFU or PFU/mL) and low (approximately 1 x 10(3)CFU or PFU/mL) population densities were exposed to currents ranging from 25 to 350 mA in 5s pulses. Post-exposure plaque counts of the bacteriophage were proportionally higher than bacterial culturable counts at corresponding current exposures. E. coli and MS2 were then exposed to 5 mA for 20 min at both high and low population densities. The inactivation rate of E. coli was 2.1-4.3 times greater than that of MS2. Both bacteria and bacteriophage were more resistant to exposure to direct current at higher population densities. Also, amelioration of inactivation within the electrochemical cell by the reducing agent glutathione indicates the major mechanism of inactivation in the electrochemical cell is disinfection by electrochemically generated oxidants. The implications of these results are that technologies relying upon direct current to reduce the numbers of microbes in food and water may not be sufficient to reduce the numbers of potentially pathogenic viruses and ensure the safety of the treated food or water.
The lifetime cancer risk and the hazard index of trihalomethanes (THMs) through oral ingestion, dermal absorption, and inhalation exposure from tap water in 19 districts in Hong Kong are estimated. The most dominant THMs are chloroform and bromodichloromethane (BDCM) in Hong Kong tap water. Among the three different pathways, residents have a higher risk of cancer through oral ingestion than through the other two pathways. The lifetime cancer risks through oral ingestion and dermal absorption for BDCM make the highest percentage contribution (59%) to total risks, followed by chloroform (24%). The chloroform and BDCM are at or above the negligible risk level of 10(-6) by a factor of 10 or more in most districts. Among the 19 districts, people living in Sai Kung have the highest risk of cancer due to the THM exposure through the multipathways, mainly because of the exposure to BDCM and dibromochloromethane (DBCM). The total cancer risk analysis indicates that each year approximately 10 out of the seven million Hong Kong residents could get cancer from the daily intake of water.
Exposure to disinfection byproducts in drinking water has been associated with an increased risk of bladder cancer. We pooled the primary data from 6 case-control studies of bladder cancer that used trihalomethanes as a marker of disinfection byproducts.
Two studies were included from the United States and one each from Canada, France, Italy, and Finland. Inclusion criteria were availability of detailed data on trihalomethane exposure and individual water consumption. The analysis included 2806 cases and 5254 controls, all of whom had measures of known exposure for at least 70% of the exposure window of 40 years before the interview. Cumulative exposure to trihalomethanes was estimated by combining individual year-by-year average trihalomethane level and daily tap water consumption.
There was an adjusted odds ratio (OR) of 1.24 in men exposed to an average of more than 1 microg/L (ppb) trihalomethanes compared with those who had lower or no exposure (95% confidence interval [CI] = 1.09-1.41). Estimated relative risks increased with increasing exposure, with an OR of 1.44 (1.20-1.73) for exposure higher than 50 microg/L (ppb). Similar results were found with other indices of trihalomethane exposure. Among women, trihalomethane exposure was not associated with bladder cancer risk (0.95; 0.76-1.20).
These findings strengthen the hypothesis that the risk of bladder cancer is increased with long-term exposure to disinfection byproducts at levels currently observed in many industrialized countries.
Chlorination of pool water leads to the formation of numerous disinfection by-products (DBPs), chloroform usually being most abundant. Bathers and pool guardians take up various amounts of DBPs by different pathways. Identification of different uptake paths is important in order to develop a technical strategy for swimming pool water treatment and to develop focussed technical solutions to minimize THM uptake. Basically, trihalomethanes (THMs) can be taken up by inhalation, by dermal absorption, or orally (swallowing of water). In our experimental study involving up to 17 participants we quantified the body burden resulting from exposure to three different concentrations of chloroform in water and air of an indoor swimming pool, during a 60 min exercising period. Chloroform concentration of the water was 20.7, 7.1, and 24.8 microg/l and was not influenced artificially. Corresponding air CHCl3 concentrations were measured at two different levels (20 cm and 150 cm) and ranged from to 85 to 235 microg/m3. To dissociate the dermal exposure route from that of inhalation, THM concentrations were measured in the blood of subjects practicing in an indoor pool with and without scuba tanks, as well as in the blood of subjects walking around the pool without swimming. Chloroform concentrations were measured in blood samples before and after each exercise period. Blood chloroform concentration of participants with scuba tanks was 0.32 +/- 0.26 microg/l, without scuba tanks 0.99 +/- 0.47 micro/l, and for persons walking around the pool 0.31 +/- 0.25 microg/l. Our results indicate that THMs are mainly taken up over the respiratory pathway. Only about one third of the total burden is taken up over the skin. We examined the relationship between blood concentration and environmental chloroform concentrations by using linear regression models. Blood concentrations are correlated to air chloroform concentrations; correlation to water concentrations is less obvious.
In Korea, data for multi-route trihalomethane (THM) exposure in households using municipal tap water treated with ozone-chlorine or chlorine are unavailable or very limited. Accordingly, the present study was designed to obtain those data by measurements of the THM concentrations in the tap water and indoor and outdoor air in the two types of households, along with an estimation of THM exposure from water ingestion, showering, and the inhalation of indoor air. Chloroform was the most abundant THM in all three media, yet no bromoform was detected in any sample. Similar to previous findings, the winter chloroform concentration in tap water treated with chlorine (22.1 microg/l, median) was significantly higher than that in the tap water treated with ozone-chlorine (16.8 microg/l, median). However, the summer water chloroform concentrations and summer and winter water concentrations of the other two THMs (bromodichloromethane and dibromochloromethane) exhibited no significant difference between the chlorine and ozone-chlorine-treated water. It was suggested that the effects of the water parameters including biochemical oxygen demand of raw water entering water treatment plants should be considered when evaluating the advantage of ozone-chlorine disinfection for THM formation over chlorine disinfection. The indoor air THM concentration trend was also consistent with the water concentration trend. The indoor to outdoor air concentration ratios were comparable with previous studies. The THM exposure estimates from water ingestion, showering, and the inhalation of apartment indoor air when not in the shower suggested that, for residents living in the surveyed households, their exposure to THMs in the home was mostly associated with their household water uses. The THM exposure estimates from tap water ingestion were similar to those from showering.
A simultaneous study on workers' and swimmers' exposure to trihalomethanes (THMs) in an indoor swimming pool has been carried out by analyzing urine samples using the headspace and gas chromatography-mass spectrometry technique. The subjects of this study were male and female workers of an indoor swimming pool as well as swimmers regularly attending the pool. The results reported show that only chloroform and bromodichloromethane were detected in the urine of those people exposed, which can be used as a specific index of exposure to these compounds. THM uptake of swimmers after 1 h of swimming was higher than that of workers after a 4 h work shift since THM levels in the workers' urine were associated only with inhalation, while levels in swimmers' urine were mainly associated with dermal absorption, apart from inhalation and occasional ingestion, as well as increased uptake due to the physical stress (swimming). The kinetics of THM excretion in the urine of the participants exposed has been calculated after termination of the exposure to select the sampling time and determine the elimination process. An interval of 15 min after exposure was selected as the sampling time, and the absorbed dosage was eliminated by 2 h after exposure. A good correlation between THM concentrations found in the swimming pool water and the urinary THM concentrations of the people affected after exposure has also been obtained.
This study intends to calculate the lifetime cancer risks resulting from intakes of trihalomethanes (THMs) in drinking water based on the presence of each THM species. The slope factors for each THM species are used, combined with exposure model and Monte Carlo simulations, to calculate the cancer risks with consideration of different exposure routes (oral ingestion, inhalation and dermal absorption). The results revealed that the highest risk comes from the inhalation exposure to chloroform during showers, which also dominates the total risk associated with chloroform exposure. For dichlorobromomethane and chlorodibromomethane, inhalation exposure also plays an important role for total risks; however, contribution from the oral consumption cannot be ignored for these two compounds. Bromoform contributes the least cancer risk among the four THM species, with a risk factor two orders of magnitude smaller than the other three THM species. For all of the four THM species, exposure from dermal absorption is not significant when compared with oral ingestion and inhalation exposures. This study also uses the THMs data collected from Taiwan to calculate the cancer risks associated with THM exposures in different areas of Taiwan. Due to the variations of the THMs compositions, it is observed that higher concentrations of total THMs do not necessarily lead to higher cancer risks. Areas with higher bromide concentration in raw water and often with higher total THM concentration may actually give lower cancer risk if the THMs formed shift to bromoform. However, this also leads to the violation of THM standards since bromoform has much higher molecular weight than chloroform. Based on the results of the cancer risks calculated from each THM species, the regulatory issue of the THMs was also discussed.
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