Fluorides exist naturally in surface water, usually at levels in the range of 0.1–0.3 mg/l; the levels in groundwater are higher depending on hydrogeological conditions. Drinking water is the main source of fluorides intake for humans.
Although fluorides (naturally occurring or added) in drinking water may reduce the incidence of dental caries, they have the potential to cause adverse health effects, like dental and skeletal fluorosis, hip fractures, osteosarcoma and neurotoxic effects. New scientific evidence has suggested that there are significant risks and negligible benefits from floridation of drinking water.
Considering the wide use of toothpastes and other dental health care products containing fluoride, as well as the increase of fluoride exposure from a number of other sources, it is important that the health risk assessment takes into account total fluoride intake, not only fluoride intake from drinking water.