Public Health Interventions for the Arsenic Poisoning of Water Supplies in India and Bangladesh: A Critical Review
By Emily Phipps
As an effort to combat diarrhoeal disease in the 1970s, shallow tube wells were introduced to Bangladesh and West Bengal, India as an alternative water source. Whilst successful in reducing mortality from water-bourne disease, in some areas the new water source was discovered to be contaminated with arsenic. In developing nations, case reporting is typically very poor; therefore, the first confirmed cases of arsenic poisoning were recorded in the 1980s. Since then, one comprehensive study in 2002 has identified 300,000 individuals with signs of arsenicosis in West Bengal alone. Arsenicosis can produce a wide spectrum of symptoms from skin lesions to nerve damage, renal disease and cancer. In Bangladesh, it has been estimated to be responsible for approximately 1,908 disability adjusted life years, a measure of years lost to ill health.
In their search for a solution, the Indian government piloted several options including alternative water sources such as dug wells, pond-sand filters, rainwater harvesting, piped water supply and arsenic filtration. However, several of these alternatives carried the burden of water-bourne disease, an issue that had previously led to the digging of the tube wells. Today, the challenge remains of which water source holds the least risk to human health, and what can be done to ensure a clean and safe supply.
A wealth of research has been conducted to try and establish the solution to this pervasive and ever increasing problem. However, rather than clarify, the subsequent studies have in turn added more confusion. Howard et al advocate the digging of deep tube wells and rainwater harvesting; whereas Lokuge et al argue a cautious approach, suggesting only intervening in areas with very high arsenic levels, but can not conclude on the best intervention. Gosh et al advocates the use of any of the above interventions along with health promotion, recommending choosing the water source best suited to the community at risk and taking into account social influences. Michael and Voss advise caution in considering the use of deep aquifers, stating that it can only be regarded as a sustainable option if restricted to domestic use alone. Van Green et al highlight that switching water sources is highly dependent on social and cultural structures and may be an important barrier to which intervention can be chosen.
Despite the varying views, all presented information must be approached with caution. Lokuge et al used data from Taiwan to calculate the arsenic attributable disease fraction, highlighting issues of generalisability. Howard et al did not measure E.Coli levels when assessing microbe levels in water supply, thus excluding an important cause of diarrhoeal illness from their study. Van Green et al noted that GPS data is not collected by researchers investigating the problem; without such data, the assumption may be made that the problem is more pervasive that it actually is. Sarkar argued that any interventions attempted in the past have been fragmented, poorly coordinated and focused on a purely biomedical model, limiting their success; he also argued that researchers do not take into consideration that farmers drink a considerable amount of the water in the fields, taken from irrigation supplies rather than wells in their homestead. This, therefore, would leave a section of society still at risk of arsenic poisoning if irrigation sources were not reviewed as well. Policy makers therefore must be extremely cautious when deciding on proposing interventions, and must consult a variety of sources to develop their conclusions.
Henceforth, there are several key factors involved in this issue, all of which must be consulted by policy makers in the decision making process to ensure a sustainable and successful intervention. Primarily, and often most neglected, are the communities and individuals themselves that use the water supply. The success of a water supply system relies heavily on the involvement and agreement of these individuals, as well as the cultural and social context in which they live. Other factors to consider include private water supply, construction companies, national water regulation boards, international NGOs and the national government, each having a key stake in the development, introduction and maintenance of water supply systems.
Therefore, with so many opinions and stakeholders, what is the best course of action for developing policy for arsenic mitigation? For policy to be successful, it needs to be sustainable, while involving stakeholders of all levels and ensuring minimum impact on the environment and animal populations. The public health, economic, social and political consequences of the policy must also be taken in to account before implementation. In their 2007 piece Howard et al urges an exercise of caution stating, “proper consideration needs to be given to other factors…that cannot necessarily be captured in a simple spreadsheet model.” Local knowledge and expert opinion is often neglected, yet they are key to a solution that will have longevity and success. In the case of arsenic mitigation, it may appear that policy decisions have been made in a ‘knee jerk’ reaction, responding to pressure from the media and charity sector. Some of the evidence used by policy makers does not take into account the social influences on water source choice, and other health impacts of interventions, essential factors that should not be overlooked.
Howard et al concluded that deep tube wells and rainwater harvesting are the safest options in terms of reducing disease burden. However, this conclusion was made from a biomedical perspective, and in turn was at risk of failure due to not being sensitive to social and cultural factors influencing water source choice. Social and cultural factors play an important role in the choice of water source: an alternative source may be safer, but if it is further away from the household or in a neighbours’ yard, it will greatly influence whether the source is used. The impact of deep tube wells on the environment can also be detrimental, as hypothesised by Micheal and Voss, and must be considered in risk management. Attempting to compare risks of several arsenic mitigation strategies, Lokuge concluded that there was insufficient data available to support policy decisions, and made the controversial statement that on a national scale “arsenic is less important than other risk factors for disease that require attention.”
The conflicting arguments surrounding the issue of arsenic contamination makes decision making a difficult challenge for policy makers. Yet, despite inconclusive evidence, mitigation strategies have already been put in place. In association with the Bangladeshi Government, UNICEF has conducted arsenic mitigation projects throughout the country, presenting communities with a range of options (deep tube wells, dug wells, rain water tanks and arsenic removal systems) for them to choose from. The German government, in addition to countless other NGO and governmental organizations, have been involved in the development of 143 arsenic removal plants in West Bengal between 2003 and 2008.
By acting quickly, the various stakeholders have used the Precautionary Principle to address the issue of arsenic contamination. The Precautionary Principle states that when a threat to human health is suspected, precautionary measures should be put in place even without the support of scientific consensus. This is a “better safe than sorry” paradigm with a focus on precaution rather than reaction. In 2001, Kriebel and Tickner described components of the Precautionary Principle as “exploring a wide range of alternatives to possibly harmful actions” and “increasing public participation in decision making.” This can be seen in the case of arsenic mitigation where a wide range of alternative water sources and water cleansing systems have been explored and put in to use, and organizations from the local, governmental and international levels have all been involved in the process of finding a conclusive solution. The human impact of arsenic poisoning is clear, and stakeholders have acted aggressively to show a quantifiable reaction that in accordance with the Precautionary Principle can be refined and adapted as more evidence comes to light.
Currently, two strategies that are proving to be the most popular with the government and NGOs are arsenic removal systems and dug wells. However, arsenic removal systems are very expensive and incur running costs on the local community. Sakar interviewed local stakeholders in one area supplied with a arsenic removal system, who stated that the system “frequently breaks down…has suboptimal filtration efficiency…[and] the highly toxic sludge is discarded in open fields.” This is clearly an unacceptable and poorly planned arsenic mitigation strategy that is not serving the community as it should. Therefore, this must serve as a lesson to illustrate that operations and management of a water supply system are as vital as providing it in the first place. In regard to dugwells, Sakar found “objection [to the] chlorine odor…lack of community ownership…[and] risk of water-bourne diseases due to poor maintenance.”
There is a sense that the basic rules of water and sanitation provision (community engagement, sustainability, environmental impact assessment) have not been considered in the case of arsenic mitigation in this area. Therefore, it is clear that a key element of the success of arsenic mitigation strategies lies not in academic research, but in engaging with the communities being aided.
Arsenic contamination is a problem that is far reaching across Asia, but is not an issue that can be solved with a universal solution. Some communities are affected to a greater extent than others, and the option that is suitable for arsenic mitigation in each case will vary according to the community’s needs and expressed requirements. A cautious approach must be taken when making decisions based on conflicting academic research, engaging with a wide variety of stakeholders at all levels before making a decision.
Emily Phipps is a medical student from the UK currently taking time out from my course to undertake a MSc Public Health at The London School of Tropical Medicine.
Works Cited
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