The Assessment of Trihalomethanes Concentrations in Drinking Water of Hamadan and Tuyserkan Cities, Western Iran and Its Health Risk on the Exposed Population

Background: the aim of the present study was to calculate and to assess the potential lifetime cancer risks for trihalomethanes from consuming chlorinated drinking water in hamadan and tuyserkan cities, western iran in 2016-2017. study design: a cross-sectional study. methods: seventy-two water samples were collected from the distribution systems and from the outlet of water treatment plants (wtps) and the experiments were carried out to determine the desired parameters. all the sampling and measurement methods were according to standard methods. the obtained data were analyzed using spss software. results: the mean concentration of total thms in the summer and winter was 42.75 and 17.75 μg/l, respectively, below the who and iranian standard. the positive correlation was observed between temperature and thms levels. moreover, thms concentration in shahid beheshti’s wtp was several times lower than in ekbatan’s wtp. chloroform, the dominant species of thms, was identified at different sampling points. the highest cancer risk in hamadan was 1.4×10^-5 and 4.8×10^-5 for male and female, respectively; and the cancer risk was obtained to be 5.6×10^-7–2.26×10^-6 in tuyserkan. conclusion: the drinking water obtained from the studied area is safe in terms of thms concentration. nevertheless, the highest cancer risk was higher than the epa’s acceptable level of 10^-6.