• This is the first report on the potential fluoride hazards in the entire coastal area of Bangladesh.
  • Fluoride concentration level of 840 coastal groundwater samples were measured.
  • About 55% samples have fluoride deficiency (<0.50 mg/L) that might lead to dental caries.
  • Almost 20% samples showed excess level of fluoride (>1.0 mg/L) might lead to fluorosis.
  • Epidemiological study is needed to find out the dental health scenarios in the study area.


Spatiotemporal distribution of fluoride in drinking water has been posing serious health concerns worldwide. However, in Bangladesh, to date, there is a very limited study reported the probabilistic health risks from fluoride content in drinking water. Therefore, we investigate the spatiotemporal distribution of fluoride concentration in drinking water and associated health risks in the coastal districts of Bangladesh based on randomly collected 840 groundwater samples (Dry-season = 302 and Wet-season = 538). Probabilistic health risk appraisal from fluoride was performed using the Monte-Carlo simulation and sensitivity analysis. Fluoride concentration in 11.89% (Wet-season) and 24.50% (Dry-season) of the samples exceeded the acceptable level of 1.0 mg/L, while 3.90% (Wet-season) and 7.28% (Dry-season) samples surpassed the maximum permissible limit (fluoride: 1.5 mg/L. The deficiency of fluoride content in groundwater (<0.50 mg/L) in Wet-season (60.41%) and in Dry-season (55.63%) was identified from the study area. The seasonality to the spatial change of fluoride concentration in drinking water has been explored. The mean non-carcinogenic risks e.g., hazard quotient (HQ) from the consumption of high fluoride-containing water for infants and children were mostly exceeded the threshold value 1 (HQ > 1) in both seasons. However, the risk of children and infants at the 95th percentile crossed the safe level (SL: 1) in the wet season and the risk of infants, children, teens and adults at the 95th percentile surpassed 1 in the dry season, indicating the potential adverse health effects. Apart from the high exposure, fluoride deficiency might be a severe problem in this region due to the very low concentration of fluoride (<0.50 mg/L) in drinking water. Sensitivity analyses indicate high fluoride-containing drinking water was the most contributing variables affecting the model outcome. Finally, the case-control study should be performed to examine further the health effects from the ingestion of high/low fluoride-bearing groundwater in the study area.