Monitoring and Health Risk Assessment of Fluoride in Drinking Water Based on Monte Carlo Simulation and Sensitivity Analysis: a Study in Rural Areas of East Azerbaijan Province, Iran

The presence of fluoride in drinking water sources at an optimal level is essential for public health and the prevention of tooth decay. The purpose of this study was to survey the fluoride level in drinking water in the rural areas of East Azerbaijan province in the northwest of Iran. Also, non-carcinogenic risk assessment, sensitivity, and uncertainty analysis for four age groups were performed using the Monte Carlo simulations with a probabilistic approach. In this descriptive cross-sectional study, fluoride concentration was measured in 1127 samples collected from rural areas of 20 counties of East Azerbaijan province (northwest of Iran) during warm (spring and summer) and cold (autumn and winter) seasons in 2017-2018. The results indicated that the average value of fluoride in drinking water varies between 0.26 and 0.59 and 0.30 and 0.59 mg/L in cold and warm seasons, respectively. The amount of fluoride in the hot and cold seasons was lower than the national standard of Iran and the guidelines of the World Health Organization in 66.00% and 63.91% of the samples, respectively. Also, the fluoride concentration in drinking water was less than the calculated optimal level using Galagan and Vermillion's equation. The order of health risks in the study groups was infants > children > teenagers > adults. The mean hazard quotient (HQ) for the four age groups, during both cold and warm seasons, was lower than one. Based on the sensitivity test, the amount of fluoride in drinking water was the most efficient agent in estimating the HQ index. According to our study, drinking water does not have a significant non-carcinogenic risk to consumers in rural areas. Therefore, more studies concerning other sources of fluoride intake will be conducted in the future and possible deficiency compensated with corrective actions such as using mouthwash and toothpaste.