National Fluorosis Day is observed on September 9 to focus attention on preventing and controlling fluorosis. The condition results from long-term excessive fluoride intake, mainly through contaminated drinking water, and can damage teeth, bones and joints. The Bureau of Indian Standards (BIS) prescribes a safe fluoride limit of 1–1.5 mg per litre in drinking water. The National Programme for Prevention and Control of Fluorosis (NPPCF) handles surveillance, prevention, early diagnosis and management of the disease.