Assessing fluoride and nitrate contaminants in drinking water resources and their health risk assessment in a semiarid region of southwest Iran

Spatial and temporal variability of fluoride and nitrate in groundwater resources of rural area of Saravan county, Iran were analyzed 2013-2017 using GIS (V10.3). The results were used for human health risk assessment, using probabilistic techniques. The annual mean concentration of fluoride during 2013 to 2017 in villages of Saravan county was 0.42, 0.62, 0.67, 0.57, and 0.55 mg L-1, and the maximum values were 1.1, 1.42, 1.76, 1.46, and 1.3 mg L-1, respectively. Also, the annual mean concentration of nitrate during 2013 to 2017 in Saravan county villages were 12.53, 14.1, 15.43, 14.34, and 14.02, and the maximum values were 66.1, 80, 35.6, 76.12, and 40 mg L-1, respectively. Spatial, temporal, and spatiotemporal variability of fluoride and nitrate in groundwater resources were relatively not constant over the years. The calculated HQ value of fluoride was for groups of infant (0.013-0.235), children (0.035-1.83), teenagers (0.067-1.1), and adults (0.053-0.94). The maximum HQ value was >1 for children and teenagers during the study period. Meanwhile, the HQ values of nitrate were (0.005-0.4) for infants, (0.035-2.69) children, (0.025-2) teenagers, and (0.02-1.6) for adults. Hence, the maximum HQ value was >1 for children, teenagers, and adult during the study period. This study showed that children, teenagers, and adult are vulnerable groups at risk of non-carcinogenic hazards for being exposed to drinking water with high fluoride and nitrate concentration.