SESSION 1 - Extent, severity and nature of Arsenic contamination
(1) The largest identified man-made environmental catastrophe
Richard Wilson, D Phil., Harvard University
The problem of arsenic in South East Asia, particularly Bangladesh is the largest identified man made environmental catastrophe. The catastrophe demands three simultaneous actions.
(1) Understanding the causes of the catastrophe;
- why was arsenic present;
- why was it made available in drinking water?; and
- why did no one recognize what was happening in time to avert the catastrophe?
(2) What exactly is the effect on humans of arsenic in the amounts present in the drinking water?
(3) How can one rapidly bring pure water to the population to avoid further damage?
and a fourth question which is less urgent but crucially important.
(4) How can the world avoid such catastrophes in the future whether from arsenic or from some presently unknown cause?
The first three were posed at an International meeting in Dhaka in 1998. I will review the appalling lack of progress in these, especially in item (3) with which I am most familiar.
(2) Predicting the Global Distribution of Natural Arsenic Contamination of Groundwater
Department of Geography, Cambridge University
Over two hundred instances of arsenic contamination of groundwater due to natural causes have been recognised from 60 countries in five continents. Arsenic is mobilised into groundwater through four common mechanisms: reductive-dissolution, alkali-desorption, sulphide oxidation, and geothermal action. In terms of impact, by far the most important is reductive dissolution, while alkali-desorption is the second most important. Evaporation may increase concentrations of arsenic initially generated by any of these mechanisms. Two main compensatory processes, adsorption and sulphate reduction, act to remove arsenic from groundwater. The mobilisation mechanisms operate in systematic geological-climatic associations. Two geological associations dominate the occurrence of arsenic. The first is with alluvial aquifers, and the second is a spatial association with recent mountain building (foreland basins). In alluvial basins, the occurrence of arsenic can be related to weathering, transportation and depositional conditions, which are reflected in the sand mineralogy and chemistry of the rivers. Although local factors may act to prevent arsenic contamination at individual locations, these associations allow regional and global predictions of where encountering arsenic-contaminated groundwater is most likely. Classified by mobilisation mechanism and geological-climatic association, the present distribution of arsenic-contamination appears irrational, with entire continents apparently lacking examples of some mechanisms. Such predictions have led to the identification of arsenic in alluvial and glacial aquifers on three continents. Regions judged to be at high risk, as opposed those merely lacking data, are identified. Testing groundwater in these regions should be a high priority.
(3) Arsenic and Manganese Contamination of Drinking Water Resources in Cambodia: Coincidence of Risk Areas with Low Relief Topography
Dr. Johanna Buschmann, Chemist, Eawag email@example.com
Mr. Michael Berg, Chemist, Eawag
Mrs Caroline Stengel, Lab Technician, Eawag
Mr. Mickey Sampson, Chemist, RDIC
The extent and severity of arsenic occurrence in Bangladesh is well-known. Although various initiatives have been taken since 1993, only a small proportion of the exposed population have access to a safe water option. Deep tube wells supply more than 90% of the safe water in arsenic affected areas; risk assessments and functionality surveys confirm that that this option has lowest risk, and is most sustainable. The Department of Public Health Engineering (DPHE) has initiated the development of a national deep aquifer database with preliminary maps. Although hundreds of thousands of deep tube wells are in operation, availability of good quality borelogs is very limited. Creation of the database is a step forward towards sustainable management of the deep aquifer. We shall critically review the concept of deep aquifer in Bangladesh; outline how the deep aquifer database was established; present preliminary deep aquifer maps; and discuss the major issues related to the sustainable management of the deep aquifer both for arsenic mitigation and as a vital natural resource for Bangladesh. We shall also highlight the existing policy and regulations regarding the deep aquifer and outline a management strategy to secure this strategic water resource for the future.
(4) High concentrations of arsenic in drinking water result in the highest known increases in mortality attributable to any environmental exposure
Allan H. Smith, Craig Steinmaus, Yan Yuan, Jane Liaw, Meera M Hira-Smith
Arsenic in drinking water continues to surprise. Invisible, tasteless and odorless, yet in the long term 1 in 10 persons with high concentrations of arsenic in their drinking water will die from it. Other environmental exposures do not result in commensurable mortality risks.
The major long term health impacts of arsenic in drinking water surprisingly occur in the lungs. And arsenic provides the first clear-cut evidence that early life exposure to an environmental toxin can result in marked increase in mortality in young adults from lung cancer.
Cancer is not the only long-term pulmonary outcome. In India subjects with arsenic-caused skin lesions have a 10-fold increased prevalence of bronchiectasis compared with subjects who did not have skin lesions (RR=10; 95% confidence interval 2.7-37). In Chile young adults aged 30-49 have a more than 40-fold increase in mortality from bronchiectasis if they had in utero exposure to arsenic in drinking water (RR=46.2, CI 21.1-87.7, p<0.001).
Most countries have some water sources with increased arsenic concentrations. The marked increase in long term health risks which greatly exceed those from any other drinking water contaminant mean that all drinking water sources in the world should be tested for arsenic.
(5) Expertise and environmental justice
Peter J. Atkins*, M. Manzurul Hassan† and Christine E. Dunn*
* Department of Geography, University of Durham, Durham DH1 3LE
† Department of Geography and Environment, Jahangirnagar University, Savar, Dhaka - 1342, Bangladesh
This paper will address the problem of arsenic in groundwater in the context of debates about expertise and legal geographies. The case of Sutradhar v NERC, which was tested recently in the British courts, is taken as a starting point for a commentary on the notion of 'proximity' between science/technology and its clientèle in the global south. In legal terms there was an alleged 'tort' - a damage and a liability - resulting from a regime of environmental monitoring that did not pick up the presence of arsenic in groundwater. The House of Lords decided that there was no case to answer but there are broader points about expertise, consultancy and 'duty of care' that remain, particularly for countries such as Bangladesh where much foreign aid is devoted to understanding and mitigating its many environmental hazards. Although torts have a long history in Anglo-Saxon common law, there is little precedent for international litigation of this sort and new styles of legal argument are required.