Twenty out of 27 districts in groundwater-dependent Assam are arsenic and fluoride contaminated. Two separate reports – one tabled in the assembly and the other following a survey – have established this.
Public health engineering minister Gautam Roy on Tuesday said arsenic content in groundwater ranged between 50 parts per billion (ppb) and 996 ppb in 19 districts. This translates into 0.05-0.996 milligram of arsenic per litre of water.
The permissible limit for arsenic established by World Health Organisation is 0.01 mg/l.
Prolonged arsenic contamination is known to cause cancer and skin diseases besides affecting reproductive health. Apart from Assam, arsenic-laced water is a serious problem in West Bengal, Uttar Pradesh, Jharkhand, Chhattisgarh, Bihar and Manipur.
A survey report by the Northeast Institute of Science and Technology also established high fluoride content in groundwater in six districts, five of which are also arsenic-affected. These districts include Kamrup Metro, where Guwahati is situated.
Groundwater in central Assam’s Karbi Anglong was found to have a fluoride content of 15-20 mg/l while in certain areas of Guwahati and outskirts it went up to 6.88 mg/l.
The WHO permissible limit is 1.5 mg/l.
Ingestion of 10-20 mg of fluoride per day for more than 10 years leads to crippling skeletal fluorosis, the report said. Inhabitants of at least half a dozen villages in Karbi Anglong district suffer from fluorosis in varying degrees.