A review on fluoride induced organotoxicity and genotoxicity in mammals and zebrafish

Abstract

Fluorine is a highly reactive electronegative element and naturally found in a combined form with other elements. In water, it remains as fluoride. It can be present in soil and air also. Beside the natural abundance, anthropogenic activities e.g. use of pesticides, fertilizers, sewage, coal burning etc. can increase the fluoride concentration in the environment. According to the World Health Organization, Permissible limit of fluoride in drinking water is 1.5\xa0ppm (mg/L). When presence of fluoride in drinking water is within the permissible limit, it exerts beneficial effects on teeth, preventing dental caries; while, chronic exposure of fluoride beyond the permissible limit causes mild to severe form of dental and skeletal fluorosis. Apart from these hard tissues, chronic fluoride exposure beyond the permissible limit causes detrimental effect on soft tissues e.g. liver, kidney, spleen, gastrointestinal tract, reproductive organ etc. Studies also indicate that fluoride induces significantly genotoxic effect both in vivo and in vitro. Although various techniques have been developed for defluoridation of water but each one has limitations. Unfortunately, till date, there is no effective strategy of fluorosis treatment. In order to develop an effective therapeutic strategy, thorough understandings on the molecular mechanism of fluoride induced toxicity should be unravelled. This review enlightens both beneficial and toxic effects of fluoride emphasizing its molecular mechanism of action.