Journal of North Khorasan

Background & Objectives: One of the main problems of utilizing the surface water sources is the high concentration of its natural organic materials, which result in reaction of chlorine with some organic ingredients in water components called thrihalomethanes, that their carcinogenic risks and destructive effects on respiratory system have been reported in humans and animals. This study aimed to examine the concentration of thrihalomethanes with chloroform index in drinking water in Mashhad city. Material and Methods: This descriptive study was carried out in 2012. The concentration of thrihalomethanes with chloroform index in water distribution network of different regions of Mashhad was measured and examined. A number of 90 randomized samples from water drinking distribution network in the area of refinery Abo & Bargh Mashhad by priority of begging to end were examined by using the gas chromatography Mass spectrometry. Results: The chloroform concentration average in drinkable water distribution network in spring and summer seasons, were 3.5±0.5 μg/l and the mean of chlorine amount remaining in distribution network were 0.6±0.2 mg/l. Conclusion: The results showed that concentration of chloroform in distribution network with 0.6±0.2 mg/l chloride amount was much more lower than accepted limit of trihalomethane in drinking water of institute of standards and industrial research of Iran and of world health organization (200 μg/l) and was lower than the limit recommended by American environmental protection agency (80 μg/l ).