Behzad Mohammadi - Department of Environmental Health Engineering, School of Public Health, Tabriz University of Medical Sciences, Tabriz, Iran.
Maryam Farajzadeh - Department of Environmental Health Engineering, East Azerbaijan Province Health Center, Tabriz University of Medical Sciences, Tabriz, Iran.
Gholam Hossein Safari - Department of Environmental Health Engineering, School of Public Health, Tabriz University of Medical Sciences, Tabriz, Iran.

Background: The overall purpose of this study was to estimate the health risk of nitrate (NO۳-) concentration in the drinking water of Tabriz County. Methods: This research is a descriptive cross-sectional study that was performed on Tabriz drinking water in ۲۰۱۶-۲۰۱۷. The concentration of NO۳- in one hundred - ninety drinking water samples was determined in the water and wastewater laboratory of the provincial health center using spectrophotometry. Results: The results showed that the average levels of NO۳- (as nitrate ion) in drinking water of urban and rural districts were ۱۴.۶ ± ۱۲.۸ and ۱۳.۱ ± ۱۲.۸ 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 ۱ in ۱۵.۲۰% of urban and ۱۰.۷% of rural samples. Conclusion: The non-carcinogenic risk of NO۳- in drinking water does not threaten the exposed population, but the children presumably are at risk of NO۳-. Hence, the continuous control of the concentration of NO۳- was recommended to prevent its possible risk for water consumers, especially children.

Risk assessment, Nitrate, Water pollution, Hazard quotient, Tabriz