Fluoride mainly enters the human body through drinking water; 96-99 per cent of it combines with bones, as fluoride has affinity for calcium phosphate in the bones. Excess intake of fluoride can lead to dental fluorosis, skeletal fluorosis, or non-skeletal fluorosis. Dental fluorosis is characterised by discoloured, blackened, mottled or chalky-white teeth. Skeletal fluorosis leads to severe and permanent bone and joint deformations. Non-skeletal fluorosis leads to gastro-intestinal problems and neurological disorders. Fluoride can damage a foetus, and adversely affect the iq of children.
Fluorosis can be detected in the neck, spine, knee, pelvis, shoulder and small joint of hands and feet. Gastro-intestinal symptoms include abdominal pain, diarrhoea, constipation, . Some neurological manifestations are nervousness, excessive thirst and tendency to urinate frequently.
In spite of all these symptoms, it is common for fluorosis to remain un-diagnosed for a long time. Also, patients often get misdiagnosed with arthritis, spondylitis, or non-specific backache. According to a 2001 study, "the occurrence of fluorosis can vary widely among different locations having almost the same fluoride concentrations in drinking water and can be affected by factors such as climate, individual susceptibility and biological response". The study also concluded that "poor nutrition also plays an important role in aggravating endemic fluorosis", thus explaining why poor people are often the worst affected.
Fluorosis is an irreversible disease and there is no cure.