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Columbia University Scientists Propose
Well-Switching as Key to Mitigating Bangladesh Arsenic Poisoning
Surprising finding of arsenic study provides opportunity to save lives
Researchers at the Earth Institute at Columbia University will announce in the September issue of the World Health Organization Bulletin the surprising results of a field survey of arsenic-poisoned drinking water in Bangladesh: 88 percent of people living in the researchers' survey area are less than 100 meters away from safe wells, even though these good wells account for only fifty percent of all the wells in their study area.
That means, according to the WHO Bulletin paper, it should be possible for millions of people currently drinking contaminated water to find water whose arsenic content falls within Bangladeshi health standards of 50-µg/l, if social and other barriers to sharing good wells can be surmounted.
This approach, coined"well-switching," by the Columbia scientists, has some practical drawbacks that need to be overcome. The vast majority of wells are privately owned, and there are considerable social barriers to women from one household fetching water from a well outside the family compound. Still, the Columbia team has anecdotal evidence that the population in their study area has responded by well-switching even more than expected. Therefore, the Columbia team feels that well-switching should be encouraged systematically throughout Bangladesh through public information campaigns.
The team's finding was based on a project in which water samples and household data were collected over a period of 4 months from 4,997 contiguous tube wells serving a population of 55,000. The position of each well was determined using Global Positioning System (GPS) receivers, a relatively inexpensive technology that could be used more frequently as part of the current blanket well-testing campaigns in Bangladesh. In this study, arsenic concentrations were determined by graphite-furnace atomic-absorption spectrometry in the laboratory, rather than using less-reliable field kits. In addition, groundwater samples were collected every 2 weeks for an entire year from six tube wells and analysed for arsenic by high-resolution inductively coupled-plasma mass spectrometry, to determine whether there were seasonal fluctuations in the arsenic levels (there were not).
Earth Institute Scientist Alexander Van Geen is also developing various field testing procedures to help local drillers to determine the depth and location of safe aquifers when digging new wells in the future. Many wells will have to be re-installed since approximately one third of the estimated 11 million wells in the country supply water containing unhealthy levels of arsenic.
Van Geen believes that market forces might offer a more effective way to mitigate the arsenic crisis in Bangladesh than a centralized government approach, which has been bogged down by various difficulties for several years.
Columbia has been central to a five year, $11 million grant with seven interdisciplinary research projects aimed at understanding and addressing the multiple facets of the arsenic problem. The Earth Institute aims to increase understanding of the Earth to enhance sustainability.
Download the World Health Organization Bulletin in PDF Format:
Promotion of well-switching to mitigate the current arsenic crisis in Bangladesh
News Release - 10/31/01:
Van Geen Wins NSF Grant for Arsenic Testing Device
News Release - 04/14/00:
Addressing the Arsenic Crisis in Bangladesh