Excessive fluoride intake in areas where the water fluoride level is above 3 mg/L can result in fluorosis , in which there is infiltration into the enamel of the teeth, producing pitting and discoloration.
Fluorosis is a crippling and painful disease caused by intake of fluoride. Fluoride can enter the body through drinking water, food, toothpaste, mouth rinses and other dental products; drugs, and fluoride dust and fumes from industries using fluoride containing salt and or hydrofluoric acid.
In areas where the level of fluoride in drinking water is less than 1 p.p.m. (0.7-1.2 mg/L), dental caries is relatively more prevalent. Fluoridation of the water provides 1-2 mg daily, resulting in a reduction of about 50% of tooth decay in children.
There is little fluoride in food except for seafish and tea, the latter providing 70% of the daily intake. Fluoride-containing toothpaste may add up to 2 mg a day.
A child may face the condition called enamel fluorosis if he or she gets too much fluoride during the years of tooth development. Too much fluoride can result in defects in tooth enamel.
Skeletal fluorosis is a bone disease caused by excessive consumption of fluoride. In India, the most common cause of fluorosis is fluoride-laden water derived from borewells dug deep into the earth.
Dental fluorosis is an irreversible condition caused by excessive ingestion of fluoride during the tooth forming years. It is the first visible sign that a child has been overexposed to fluoride.
According to recent estimates, dental fluorosis now effects an average of 48% of children in fluoridated communities (York Review 2000), marking an almost 5-fold increase in fluorosis since the 1940s. (In the 1940s, dental fluorosis rates in fluoridated areas averaged 10%.)