NEW DELHI: With one-third of Delhi's groundwater laced with excessive fluorides, the number of people falling prey to fluoride poisoning is increasing. The problem has been detected in large parts of west Delhi including Dwarka sector 8, Poothkalan (near Rohini), Nangloi, Kakrola, Dichau and Rajouri Garden.

Even areas such as Kanjhawla, Pragati Vihar and Nizamuddin have as much as four to five times the permissible limit, which is 1.5 mg/l, the desirable limit being 1 mg/l.

According to doctors, there are three forms of fluoride poisoning or fluorosis, the most common being dental fluorosis. The other two forms are skeletal and non-skeletal fluorosis.

Dental fluorosis causes yellow, brown or black streaks or spots on the teeth. There is no cure for dental fluorosis. "It is this physical symptom which makes people aware, whereas skeletal fluorosis can go undetected for a long time," said Lady Hardinge Medical College's Pravesh Mehra. He receives about 2 to 3 patients of dental fluorosis every month.

The problem is more serious in outer Delhi. "A large number of people suffering from dental fluorosis have been found to be consuming ground water. Though not many people go in for cosmetic changes, due to the rural character of this area," said a doctor with Maharaja Balmiki hospital in Pooth Khurd. The hospital receives about 10 patients every month.

Executive director of Fluorosis Research and Rural Development Foundation, A K Susheela said a large number of patients are directed to the foundation since tests for fluoride were not part of the routine blood and urine tests conducted at government hospitals. Meanwhile, the non-skeletal fluorosis affects the soft tissues in the body and one may develop health problems in a very short interval.