Title : Testing of water for arsenic in Bangladesh

Authors : A. Mushtaque R. Chowdhury, M. Jakariya

Abstract : The testing of water supplied by hand-pumps, of which there are more than 2.5 million, is itself a formidable job. BRAC, a local nongovernmental organization, has tested a method for large-scale, field-level arsenic testing by training village-based community health workers (CHWs) (2) using a field kit. The kit, developed by the Asian Arsenic Network of Japan, determines the presence of arsenic in water through chemical reactions and works in the following manner: in groundwater, arsenic usually occurs as arsenite (As-III) and arsenate (As-V), and the kit reduces arsenate to arsenite by potassium iodide (KI) and stannous chloride (SnCl2). The As-III is then reacted with zinc and hydrochloric acid (HCl) to produce arsenic gas. A color change from light-yellow to reddish-brown on bromide paper indicates the presence of arsenic in the water. Forty CHWs in a subdistrict previously known to be arsenic-affected were trained to use the kit. They then tested water from all 11,954 hand-pumps in 156 villages. Results showed that water from 93% of the hand-pumps was contaminated. A subsample of the water samples simultaneously tested in a government laboratory using a spectrophotometer confirmed the field testing in 92% of the cases. The cost of the testing was less than 50 cents per water sample, which is only a fraction of what it costs in a laboratory. This mass testing at the field level also aroused enormous awareness among the villagers about the arsenic problem. On the basis of this experience, BRAC is now working with the government and UNICEF to test the water supplied by all the 18,000 hand-pumps installed in the country in 1998

Journal : Science Volume : 248 Year : 1999 Issue :
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