en Environmental Health, Sciences, and Engineering Environmental Health, Sciences, and Engineering پژوهشي Original Article &nbsp; <div style="text-align: justify;"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><strong>Background:</strong> The overall purpose of this study was to estimate the health risk of nitrate (NO₃^-) concentration in the drinking water of Tabriz County.<span dir="RTL"></span><br> <strong>Methods:</strong> This research is a descriptive cross-sectional study that was performed on Tabriz drinking water in 2016-2017. The concentration of NO₃^-in one hundred - ninety drinking water samples was determined in the water and wastewater laboratory of the provincial health center using spectrophotometry.<br> <strong>Results:</strong> The results showed that the average levels of NO₃^- (as nitrate ion) in drinking water of urban and rural districts were 14.6 &plusmn; 12.8 and 13.1 &plusmn; 12.8 mg/L, respectively, which are lower than the national standard of Iran and WHO guidelines. The average hazard quotient (HQ) for four age groups of infants, children, teenagers, and adults was less than one in both urban and rural zones. However, HQ values for the children were more than 1 in 15.20% of urban and 10.7% of rural samples.<br> <strong>Conclusion:</strong> The non-carcinogenic risk of NO₃<s>^-</s> in drinking water does not threaten the exposed population, but the children presumably are at risk of NO₃^-. Hence, the continuous control of the concentration of NO₃^-was recommended to prevent its possible risk for water consumers, especially children.</span></span></div> <gdiv></gdiv> Risk assessment, Nitrate, Water pollution, Hazard quotient, Tabriz, 15 21 http://jhehp.zums.ac.ir/browse.php?a_code=A-10-423-1&slc_lang=en&sid=1 Behzad Mohammadi behzad.khangahi@gmail.com 100319475328460011138 100319475328460011138 No Department of Environmental Health Engineering, School of Public Health, Tabriz University of Medical Sciences, Tabriz, Iran. Maryam Farajzadeh farajzadehm699@gmail.com 100319475328460011139 100319475328460011139 No Department of Environmental Health Engineering, East Azerbaijan Province Health Center, Tabriz University of Medical Sciences, Tabriz, Iran. Gholam Hossein Safari hsafari13@yahoo.com 100319475328460011140 100319475328460011140 Yes Department of Environmental Health Engineering, School of Public Health, Tabriz University of Medical Sciences, Tabriz, Iran.