Fluoride is used to prevent tooth decay by its addition to municipal water supplies and dental products (such as toothpaste). Fluoride is also used in consumer products (such as cleaning supplies) and industrial applications. People are primarily exposed to fluoride from drinking water and use of fluoridated products. Water fluoridation represents 30% to 70% of an individual’s total exposure. Workers in some occupations may be exposed to fluoride by inhaling fluoride compounds at their place of employment.
NTP is undertaking a programmatic activity to look at potential health outcomes from exposure to fluoride. As part of this activity, NTP has completed a systematic review of the published animal literature (rats and mice) looking at neurobehavioral effects of exposure to fluoride during development and adulthood. NTP’s assessment found a low to moderate level of evidence that the studies support adverse effects on learning and memory in animals exposed to fluoride in the diet or drinking water. The evidence was strongest in animals exposed as adults and weaker in animals exposed during development.
No studies evaluated developmental exposure to fluoride at levels as low as 0.7 parts per million, the recommended level for community water fluoridation in the United States. Additional research is needed. NTP is conducting laboratory studies in rodents to fill data gaps identified in the systematic review of the animal studies. The findings from those studies will be included in a future systematic review to evaluate potential neurobehavioral effects from exposure to fluoride during development with consideration of human, experimental animal, and mechanistic data.