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Evaluation of Trihalomethanes Levels in Gharbiya Governorates Drinking Water

Chlorination is the most accepted disinfectant throughout the world because of its economical availability and effectiveness against the waterborne pathogens. Chlorination worked effectively against the microorganisms and provide safeguard against several waterborne diseases [1,2] on the other hand, it reacts with natural organic matters (NOMs) to form disinfection by-products (DBPs). Studies have shown a relationship between long-term exposure to DBPs and increase risk of cancer and adverse reproductive outcomes [1,2]. Trihalomethanes (THMs) are the most abundant DBPs [3,4]. THMs constitute a major class of DBPs, including chloroform (CHCl3), bromodichloromethane (CHCl2Br), chlorodibromomethane (CHClBr2) and bromoform (CHBr3). Since THMs concentration in water is a serious health concern and United States, European Union (EU) and World Health Organization (WHO) regulated THMs in public water supplies [5]. Several factors in addition to NOMs influenced the formation of THMs including the nature of source water, amount and time of contact of chlorine, levels of total organic compounds (TOC), temperature and pH etc. [5,6]. Water from water treatment plant and tap water is generally used not only for drinking but also for washing, cleaning, cooking, showering, and bathing. The water constituted of contaminants i.e., THMs was potential to expose through ingestion during drinking or bathing, contact with skin as dermal absorption and even inhalation of the risk compounds. Several studies were estimated the lifetime cancer risk and non-carcinogenic risk for THMs through mutipathway exposure routes. The risk assessment for water was commonly calculated to ingestion exposure to toxic compound. Presently, the other routes of exposure in dermal and inhalation exposure may be more important than direct ingestion exposure [7,8]. In Hong Kong, the researcher reported that the cancer risk and hazard index of THMs from tap water that exposed through ingestion route higher than dermal and inhalation routes. The another research study also reported that the THMs in Beijing and Canada drinking water were higher risk through oral ingestion than through other two pathway (dermal and inhalation) and female was more exposed of THMs than male. The reported level of THMs in drinking water supply in Istanbul stated that oral ingestion was found at highest concentration and chloroform was mostly detected in water [7,8]. However, the study in Taiwan revealed that the Chloroform in water was highest risk from the inhalation *Corresponding author: Ali M Abdullah, PhD, Technical Support Manger, HCWW, Alexandria, Egypt, Tel: 00201229248037; E-mail: dr2252000@dr.com


Introduction
Chlorination is the most accepted disinfectant throughout the world because of its economical availability and effectiveness against the waterborne pathogens. Chlorination worked effectively against the microorganisms and provide safeguard against several waterborne diseases [1,2] on the other hand, it reacts with natural organic matters (NOMs) to form disinfection by-products (DBPs). Studies have shown a relationship between long-term exposure to DBPs and increase risk of cancer and adverse reproductive outcomes [1,2]. Trihalomethanes (THMs) are the most abundant DBPs [3,4]. THMs constitute a major class of DBPs, including chloroform (CHCl 3 ), bromodichloromethane (CHCl 2 Br), chlorodibromomethane (CHClBr 2 ) and bromoform (CHBr 3 ). Since THMs concentration in water is a serious health concern and United States, European Union (EU) and World Health Organization (WHO) regulated THMs in public water supplies [5]. Several factors in addition to NOMs influenced the formation of THMs including the nature of source water, amount and time of contact of chlorine, levels of total organic compounds (TOC), temperature and pH etc. [5,6]. Water from water treatment plant and tap water is generally used not only for drinking but also for washing, cleaning, cooking, showering, and bathing. The water constituted of contaminants i.e., THMs was potential to expose through ingestion during drinking or bathing, contact with skin as dermal absorption and even inhalation of the risk compounds. Several studies were estimated the lifetime cancer risk and non-carcinogenic risk for THMs through mutipathway exposure routes. The risk assessment for water was commonly calculated to ingestion exposure to toxic compound. Presently, the other routes of exposure in dermal and inhalation exposure may be more important than direct ingestion exposure [7,8]. In Hong Kong, the researcher reported that the cancer risk and hazard index of THMs from tap water that exposed through ingestion route higher than dermal and inhalation routes. The another research study also reported that the THMs in Beijing and Canada drinking water were higher risk through oral ingestion than through other two pathway (dermal and inhalation) and female was more exposed of THMs than male. The reported level of THMs in drinking water supply in Istanbul stated that oral ingestion was found at highest concentration and chloroform was mostly detected in water [7,8]. However, the study in Taiwan revealed that the Chloroform in water was highest risk from the inhalation exposure during shower and dominated to the total risk of THMs. This study also showed that exposure from THMs dermal absorption is not significant comparing to oral and inhalation exposure. The importance of THMs inhalation exposure route was also reported in India that accounted of 80-90% of the total risk followed by oral exposure and dermal absorption. Chloroform was found to be major THMs. One study in Thailand was investigated the THMs in tap water and swimming pool water in Nakorn Pathom. Results showed that the concentration of THMs in swimming pool water was higher than in tap water and cancer risk from skin exposure while swimming was 94.18% of the total risk. The three exposure route of exposure may be attributed to different concentration and species of THMs present in water [7,8]. The variation of THMs can also influence temporally and seasonality influenced the THMs formation process. Different studies on seasonality dependency showed variable results in summer and winter [6,9].

Materials and Methods
Water samples were collected from different parts of the governorate representing main distribution network of water supply. Sampling locations were shown in Figure 1. Total 48 sampling locations were sampled during the present study. Samples for THMs analysis were collected in headspace-free borosilicate amber glass bottles with Teflon joint screw cap, containing 1.7 mL of 10% sodium thiosulfate as quenching solution to remove any residual chlorine. Temperature, pH and free chlorine were measured in the field. Once collected, samples were stored in the dark at 4°C and carried to the laboratory for analytical procedures. Measurements of free chlorine were measured in the field using the DPD4 and disk comparator. AEPA method 551.1 was used

Abstract
The occurrence of trihalomethanes (THMs) was studied in the drinking water samples from Gharbiya governorate water treatment plants and its water supply network that served more than 5 million people. Drinking water samples were collected from 7 sites monthly over one year (2012)(2013) to determine the THMs (CHCl 3 , CHCl 2 Br, CHClBr 2 and CHBr 3 ). 4 mL of was added to 25 mL of sample in 40 mL glass vials. The upper phase layer of n-Pentane was separated by manual shaking for 1 minute and 1 µL Pentane layer was injected into the CP-3800 gas chromatograph (GC). The GC was equipped with DB 5 (30 m, 0.32 mm i.e., 0.25 µm film thickness) chromatographic column and the analytical conditions were set as: injection split ratio 1:20; oven temperature 30°C for 5 min, 30-120°C at 6°C/min; carrier gas Helium 1.0 mL min -1 , makeup gas N 2 60 mL min -1 ; detector (ECD) temperature 300°C. DB-1301 capillary column was used for the confirmation of the THM analysis. Field blanks were used to determine any background contamination. Method blanks and spiked blanks were analyzed. The recoveries obtained for CHCl 3 , CHCl 2 Br, CHClBr 2 and CHBr 3 were 93-109, 88-106, 92-111, 96-108 and detection limits (four compounds) 1.0 µg L -1 respectively were ensured by the analytical procedure [10] .

Results and Discussion
The data presented in (Tables 1 and 2) and (Figures 2, 3, 4 and 5), showed that, the seasonal variation of disinfection by-products (THM) in four water treatment plants (WTP) in El Garbyia governorate.       Table 1 and Figure  3. The THM and its species values were complying with the Egyptian standard (Ministerial Decree No.458/2007) and as well as WHO (2012) standards for drinking water [11,12].  Table  2 and Figure 4. The THM and its species values were complying with the Egyptian standard (Ministerial Decree No.458/2007) and as well as WHO (2012) standards for drinking water [11,12].  Table 2 and Figure 5. The THM and its species values were complying with the Egyptian standard (Ministerial Decree No.458/2007) and as well as WHO (2012) standards for drinking water [11,12]. The THM formation generally favoured by high temperature, chlorine residue and source water natural organic matters composition (NOMs) [6,9,13]. The observed seasonalvariation of THMs was consistent with earlier studies reported maximum THM formation in summer [9,13,14]. CHCl 2 Br and CHClBr 2 exhibit inconsistent higher mean seasonal variations in winter and spring than summer and autumn (Figures 2, 3, 4 and 5). These higher mean values in winter can be attributed to characteristics of natural organic matter and changes inthe nature of THMs precursors in the source water [13,14].

Conclusion
Present study found considerable variation in THM concentration between the four seasons. The THM and its species values were complying with the Egyptian standard (Ministerial Decree No.458/2007) and as well as the EPA (2012) and WHO (2012) standards for drinking water. The THMs level followed the general trend of higher concentrations in summer and autumn compared to winter and spring with large variations in the concentration level. It is difficult to identify the principal parameter(s) driving the THMs formation for all the seasons in the presence of complex nature of  This article was originally published in a special issue, Organic Chemistry and the Environment handled by Editor(s). Mohd Rafatullah, MHandling Editor University : University Sains Malaysia source water NOMs matrix. A comprehensive monitoring program of the THMs in the urban and rural water supply is recommended to facilitate the evaluation of principal factor(s) causing elevated levels of THMs, which may cause adverse health effects.