Background: Fluorine is an essential element for dental and skeletal health which is obtained paimarily from drinking water. However, large doses of flourine can lead to dental and skeletal fluorosis. Fluorine intake is affected by local climate conditions, air temperature, and water consumption. Symptoms of dental fluorosis were observed in the residents of Souri. Since a bibliographic survey showed that no study has been undertaken so far in this area with regard to fluoride, the aims of this research was to determine fluoride concentration in drinking water, and to estimate an optimum fluorine dose level as well as the daily exposure dose among distinct age groups in Souri region, Lorestan.
Materials and Methods: To determine fluorine concentrations in drinking water and assessment of probable risks in Souri region, Lorestan, in total 19 groundwater samples, including 4 samples from springs and 15 from wells (one sample per sampling location) were collected in December, 2016.
Results: The average content of fluorine was 1.26 milligram per liter with a range of 0.67 to 1.9 milligram per liter.  The optimal dose of fluorine was calculated to be 0.79 mg/L., The estimated fluoride intake from drinking water in the three different age groups of adults, children and infants was 0.6, 1.86 and 4.13 times highher than the current minimum risk of 0.5 mg per kg per day. In order, infants, children and adults are highly exposed to the risk of developing dental fluorosis disease.
Conclusion: Fluorine concentration exceeded the standard level of 1.5 mg/l recommended by World Health Organization in 42% of the water samples. This phenomenon has led to the increased incidence of dental fluorosis among the residents of the investigated region. The rise of fluoride intake, particularly when the residents of the investigated region are unaware of the consequences, leads to the high risk of developing dental fluorosis.