For over 40 years health authorities stated that in order to develop crippling skeletal fluorosis, one would need to ingest between 20 and 80 mg of fluoride per day for at least 10 to 20 years.
The risk for developing skeletal fluorosis, and the course the disease will take, is not solely dependent on the dose of fluoride ingested. Indeed, people exposed to similar doses of fluoride may experience markedly different effects. While the wide range in individual response to fluoride is not yet fully understood, the following are some of the factors that are believed to play a role:
- Impaired kidney function
- Polydipsia (Excessive thirst)
- Dietary deficiencies
- Acidosis (gastric acidity, rental tubular acidosis, etc)
- Repetitive physical stress