Reducing Arsenic Exposure in Bangladesh
A team of drillers test a new coring device in November 2005 in the village of Lashkardi, Bangladesh. Researchers at Columbia University are working to help the 30 million Bangladeshis who are at risk from arsenic-contaminated water.
The UN has called it the single worst case of mass poisoning in human history. Others have called it a tragedy of good intentions. Regardless of one's perspective, it is a problem with no easy answers. In Bangladesh, more than 30 million people are at risk of a wide range of health effects associated with arsenicosis, or chronic arsenic poisoning.
With much of Bangladesh situated over the Ganges-Brahmaputra-Meghna Delta, the country has ample supplies of clean groundwater that can be tapped by driving a pipe as little as 50 feet into the ground. In the 1970s, international agencies and private citizens began installing millions of simple, inexpensive tubewells. They were motivated primarily by efforts to reduce the Bangladesh's high infant mortality rate, which was driven largely by deaths due to diarrheal diseases that were the result of microbial contamination of surface water.
In 1993, it was discovered that some aquifers contained naturally occurring arsenic in concentrations as high as 500 micrograms per liter (μg/l) — 50 times the maximum acceptable level set by the World Health Organization (WHO).
As a result, nearly 30 million people are believed to be at risk of severe health problems associated wtih arsenicosis, including thickening and hardening of the hands and feet, skin cancer, bladder cancer, lung cancer, vascular disease leading to gangrene, and diabetes.
With visibly polluted ponds and streams the only alternative to the clear, arsenic-tainted water, however, more than 80 percent of the population continue to rely on public or private wells — and new tube wells are being installed at ever-increasing rates.
In 2000, a team of researchers from Columbia University composed of public health experts, geologists, sociologists and engineers arrived in Bangladesh to better understand the human health implications of arsenicosis as well as the geology and geochemical processes behind the arsenic contamination. Their aim was also to devise inexpensive ways to give people more reliable access to clean, arsenic-free water.
The team was initially funded by a five-year, $11 million grant from the Superfund Basic Research Program administered by the National Institutes of Environmental Health (NIEHS). The grant was recently renewed for six years at $16.9 million.
The team has focused on a district in southern Bangladesh known as Araihazar, in part because the region's complex geology has produced a mix of high- and low-arsenic wells near each other. In addition to collecting health data and blood and urine samples from local residents, the scientists also began studying people's knowledge of the arsenic problem and attitudes towards various mitigation methods. They have also helped install and are continuing to monitor 50 community wells in villages with no reliable access to safe water as well as test and label all the wells in the district.
One simple tool the team has developed is a well-tracking system that uses local cell phone networks to access a database cataloging the depth and arsenic concentration for half of the estimated 10 million wells throughout the country. The data was generated in the late 1990s by the Bangladesh Arsenic Mitigation Water Supply Program (BAMWSP), now known as the Bangladesh Water Supply Program Project (BWSPP), to better understand the magnitude and distribution of the arsenic problem. By accessing the network over an SMS-enabled cell phone, a well-drilling team in the field can quickly determine the minimum safe depth to low-arsenic water, thereby reducing the time and cost associated with installing a new well. Other tools the team has developed make it easier to obtain water samples while a well is being drilled.
Mark Becker, Center for International Earth Science Information Network (CIESIN)
Meredith Golden, Center for International Earth Science Information Network (CIESIN)
Andrew Gelman, Columbia University
Brian Mailloux, Barnard College