4 Water/Wastewater
Arsenic Contamination of Groundwater in Bangladesh
The contamination of groundwater by arsenic is a vast and urgent public health issue for Bangladesh and West Bengal. The problem began approximately 30 years ago when well-intentioned international aid organisations made a strong financial push to install tube wells across much of rural Bangladesh. These efforts were motivated by the desire to reduce the outbreak of waterborne illnesses, such as diarrhoea, amebiasis, and typhoid. In addition to these public health goals, the installation of tube wells also reduced the daily and domestic workload of the households in the regions. Tube wells saved time and labour spent to capture water at more distant sources and then transport the water to the home. Since the 1970s and 1980s, the deployment of these tube wells has been linked to several positive public health outcomes, including reductions in the outbreaks of waterborne disease epidemics and reductions in infant mortality rates.
Exposure to arsenic can lead to a number of harmful effects on an individual’s health.
In spite of these improvements, during the time when tube wells were being installed across Bangladesh, the presence and the extent of arsenic-contamination in the groundwater was not known. By the early 1990s, more than a decade after the first tube wells were installed, the first cases of arcenicosis were diagnosed and linked to arsenic- contamination of groundwater.
Recent estimates of the scale of the arsenic contamination problem suggest that as many as 35 million individuals are exposed to arsenic contamination levels that exceed Bangladeshi standard for arsenic of 50µg/L. As many as 57 million individuals may be exposed to levels that exceed the arsenic guideline established by the World Health Organization level of 10µg/L. As much as 13% of the population of Bangladesh may be currently relying on water supplies contaminated with arsenic. In addition to causing human health problems from direct exposure to arsenic-contaminated waters, arsenic has been detected in soils that are irrigated with contaminated water as well as in agricultural products such as rice and leafy vegetables.
While isolated occurrences of the arsenic-contamination in Bangladesh and West Bengal may be due to anthropogenic activities, the large geographic scope of the problem suggests that the most probable source is more likely to be geological. Sediments deposited during the Holocene era about 12,000 years ago contain Arsenic, which then leached into and contaminated the water of the aquifer. Once in the aquifer, the contaminated water was extracted using tube wells and then put to use extensively for domestic and agricultural purposes.
Health impacts of arsenic Author Details:
Andrew J. Leidner Ph.D. Student and Research Associate Department of
Agricultural Economics Texas A&M University
College Station, Texas 77801 Email:
andrew.leidner@gmail.com
Exposure to arsenic can lead to a number of harmful effects on an individual’s health. Arsenic contamination has been linked to skin cancer and a list of internal cancers that includes liver, lungs and bladder cancers. In addition to being linked to cancers, arsenic has also been linked to problems of the respiratory system, cardiovascular disease, strokes, diabetes, skin pigmentation abnormalities, and keratosis.
The full scope of the public health impacts in Bangladesh associated with this arsenic-contamination event is unknown and may remain so for many years. Cancers linked to arsenic-contamination may be latent for up 20 years. Other impacts from ongoing arsenic exposure may also take time to manifest themselves as observable and recorded health impacts. Most studies agree that the outlook for this environmental tragedy is grim.
Map of Bangladesh Monitoring arsenic
Efforts to monitor the arsenic concentration are important for at least two primary reasons. First, these efforts, when conducted on existing wells, give perspective to the arsenic-contamination problem and can provide guidance for the targeted implementation of contamination mitigation strategies, such as the installation of arsenic-removing filters. Secondly, when monitoring efforts are applied to wells sites that are under consideration or under construction, the public health problems caused by exposure to arsenic may be reduced or forgone entirely.
Several water quality tests are available for use in the laboratory to estimate the level of arsenic in a water sample. In addition to proper laboratory procedures, proper sample collection and transportation are important for any of the laboratory tests to generate reliable results. Several mobile water quality testing kits are available, but the development of even more reliable and user-friendly field testing techniques are an ongoing enterprise. Relative to laboratory tests, some of the advantages of field testing include the ability to avoid problems
AET Annual Buyers’ Guide 2012
www.envirotech-online.com
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