Neurological menifestations of fluorosis occur , when the duration of ingestion is:
The fluoride dosage necessary to produce pathological skeletal fluorosis is estimated to be 20-80 mg/day for a period of 10 to 20 years. In India, it is most commonly seen in Punjab. Neurological Manifestations of fluorosis occur if the duration of ingestion is more than 20 years.
10 years
15 years
20 years
25 years.