One Solution to the Arsenic Problem

VERSION of June 11th 2005

ONE SOLUTION TO THE ARSENIC PROBLEM:

A RETURN TO SURFACE (IMPROVED DUG) WELLS

Sakila Afroz Joya, Bivash Chandra Barmon, Ariful Islam, Golam Mostofa, Altab Elahi, Jabed Yousuf , Golam Mahiuddin, Mahmuder Rahman, Quazi Quamruzzaman

Dhaka Community Hospital

Richard Wilson

Department of Physics

Harvard University

A brief history of Worldwide Arsenic Use

Arsenic has been used since 3000 BC [1]. In the United Kingdom, for example, it was used to extract iron from iron ore. It has long been known that arsenic is acutely toxic. Anyone who drinks arsenic in water at 60 parts per million (ppm) will soon die. Miners took particular precautions to avoid exposure. Arsenic was also used for criminal purposes to poison a rival and may, for example, have been used to poison Napoleon in his exile.

However, chemicals and substances are often only dangerous at high doses. Indeed at lower doses beneficial effects can often occur. Arsenic has been used for about 2 centuries for medicinal purposes. At fairly high doses it was successfully used as a cure for syphilis before antibiotics entered the pharmacopoeia 70 years ago. Arsenic in moderately high doses repeated over a month has been shown to assist in curing some leukemia[2]. In a 1% solution of arsenite[3] it was introduced in 1785 by Dr. Fowler, of Edinburgh, (UK) and was an imitation of a popular remedy known as "Tasteless Ague and Fever Drops." It was used as a “mild tonic for digestive disorders”.. That arsenic at low levels is safe seemed to be reinforced by animal studies that seemed to show that arsenic is beneficial (to animals) at low doses. Indeed, the fact that laboratory animals (mice, rats, cats, and dogs) could not be persuaded to develop cancer misled toxicologists throughout the world and greatly contributed to the present catastrophe in Bangldesh. One of the present autors (RW) contributed to this misunderstanding by arguing that the observed carcinogencity of arsenic was probeably due to inhlation exposure.[4] Others have written about other possible beneficial effects at very low levels.[5]

Thus a myth developed that while the acute effects of a large single dose are lethal, the chronic effects of a small repeated dose were either small or beneficial. But we now know that this perception is wrong.

Another myth is pervasive throughout society and across cultures. That the effect of an ingested or inhaled substance is either adverse or beneficial but not both. We now know that it can be both simultaneously, even at the same dose, with one medical outcome being beneficial and another adverse. For chronic exposures, the adverse effects of arsenic dominate.

A brief history of water use in Bangladesh

Water is life. Water for human consumptionshould be potable, which should be:

-Easily accessible

-Adequate in quantity throughout the year

-Free from contamination

-Clear

-Pleasant to taste

-Odorless

-Arsenic free

-Germ free

-Toxin free

-Acceptable

-Affordable

-Convenient

-User friendly

-Sustainable

People of Bangladesh in the past 40 to 50 years, have been abstracting this water from

ground water by sinking hand/shallow tube wells and deep tube wells for drinking and domestic water and also for irrigation. The water available in the saturation zone (pores completely filled with water) is known as ground water. Physically ground water is generally clear, colorless with little or no suspended solids. The water is also free from diseases producing microorganisms, which causes high prevalence of diarrheal diseases in Bangladesh. The only disadvantages seemed to be due to high iron content (the iron makes cooked food blackish in color) and hard.

Ground water is available in large quantities in shallow depths. The amount of ground water that can be obtained from an area depends on the characteristics of the underlying aquifer and the extent and frequency of recharge. Betweeen 1980 and 2000, Bangladesh achieved a remarkable success by providing 97% of the rural population with bacteriologically safe tube well water. This success led simultaenously to a disaster. Rural people were made aware of the importance of drinking bacteriologically safe water and rapidly developed their habit of drinking Tube Well water. Unfortunately arsenic in shallow ground water aquifers is at an unacceptable level. Data from the Brtish Geological Survey (BGS) were used to estimate that 30 million people in Bangladesh are living with arsenic at levels greater than 50 g/l [6] but 50 million people in Bangladesh are living with arsenic at levels greater than 10 g/l and are therefore under the threat of arsenic poisoning. However scientists at Dhaka Community Hospital estimate an even higher number - possibly 80 million people are at risk of arsenic poisoning in Bangladesh. Of these a large fraction – between 200,000 and 1,000,000 will develop skin lesions or internal cancers as estimated, for example by Harvey et al.[7]

Today possibly more than 3 million affected shallow tube wells are used for drinking water. Out of the total 64 districts of Bangladesh, in 50 districts arsenic has been found above 50 µg/l (the recommended level of arsenic in drinking water of Bangladesh) and in 60 districts above 10 µg/l (which is the World Health Organization (WHO) recommended maximum level of arsenic in drinking water).

Soon after the arsenic problem was discuvered, it was widely suggested that a simple option is to drill te wells deeper – to below a clay layer where the water is relatively arsenic free.

But in some areas the deep tube wells are found to be already contaminated with arsenic so that this is not a solution. Moreover it is feared that the deep aquifer may become contamitated with use.

In some villages 100% tube wells are contaminated with high level of arsenic. DCH and Dipankar Chakraborti, Jadovpur University, Kolkata, India, jointly surveyed on arsenic affected areas of Bangladesh and prepared the following maps (Fig. 1&2). Similar maps have been prepared by others such as the British Geological Survey[8]. A listing of tube wells and their measurement is available at NAMIC.[9]

Figure-1 Figure-2

Moreover in Bangladesh the water demand is increasing rapidly. 82% of the water supply system depends (in 2005) on ground water of which 95%goes for irrigation and only 5% used for drinking and cooking. In Dhaka continuous extraction of ground water is non rechargeable at the same rate of extraction, and has resulted in severe lowering of the ground water level. According to the WASA report 2003 [10], the ground water level that was 11m in 1970s went down to 20m in 1980s. It is estimated that it will go below 45m by 2016. Which, it is predicted, will create a severe crisis to meet future water demand. If reliance is placed on deep tube wells the same may happen elsewhere. So we have to reduce the load on ground water use and have to make alternative water supply options based on arsenic free surface water that is abundant in Bangladesh and was historically the source of water. Surface water is abundant in the wet season in Bangladesh. An estimated 795,000 million cubic meter of surface water is discharged per year through the Gangaes and Brahmaputra. This is equivalent to 5.52 m deep water over the land area of 144,000km2.

The Government of Bangladesh (GOB) in its national policy on arsenic mitigation[11] gave priority to surface water use among other options. Most of the people used dug wells along with other surface water sources before 1985 when tube wells were suggested and encouraged. The only problems of these surface water options are contamination with high level of bacteria along with few other contaminants (such as iron, and phosphate).

These can be overcome easily if the surface water can be treated and maintained properly. Due to poor management and improper investment, we are hardly utilizing the abundant surface water with which Bangladesh is blessed. Now time has come to protect our next generation from drinking arsenic poisoned ground water by proper management of surface water, which is an easily available and affordable water source for the people of our country, and it is also easy to keep safe. In the past years DCH has established 224 Dug Wells, 9 Pond Sand Filters, 5 River Sand Filters and 1,122 systems for Rainwater harvesting. The original 66 dugweels described in this paper have always been free oof bacteiaa, but about 18 dugwells dug later in the Sirajdikhan upazila had contamination after an unusually severe flood and had to be retreated by DCH and now all of them are safe and working. Pond Sand Filters (PSF), River Sand Filters (RSF), and the Rainwater Harvesting systems that are models of safe water provided by DCH are also working satisfactorily.

The worldwide mistake

Starting about 1980 it was suggested that Bengalis, both in Bangladesh and West Bengal, should switch from the use of the abundant, but unsanitary, surface waters, to the use of ground water using simple tube wells. This seemed to have the advantage of vastly improved sanitation, and hopefully a reduction in the incidence of cholera. This was particularly urged by a wide spectrum of western agencies: the World Bank, UNICEF and The British (UK) Geological Survey in particular. In retrospect it is curious that none of these agencies, and none of the “bystanders” insisted, or even seem to have suggested, that the ground water be tested for arsenic and other heavy metals. With 2,000,000 tube wells sunk by, or on behalf of, these agencies and another 8,000,000 sunk privately it is surprising that not even a small sample of these wells were so tested. Even if a sample of 100 wells had been tested in 1980, the agencies would have been alerted.

Early warning signs of chronic adverse effects

As early as 1888 Hutchinson[12][13] published data showing adverse effects on the human skin from prolonged use of Fowler’s solution. Lung cancers were attributed to inhalation of arsenic pesticides as early as 1897. Neubauer[14], among others, had described arsenical cancers in 1947 Skin pigmentation, keratoses and skin cancers were found by Tseng[15][16] in Taiwan among people who drank from arsenic contaminated wells (but no effect was seen below about 150 parts per billion (ppb), which might therefore be a biological threshold). Dr KC Saha in Kolkata (India) reported in 1980[17] that there were cases of arsenic poisoning in West Bengal. But these early warnings were ignored.

The world was finally alerted to unusual risks by the report of a very high incidence of lung, bladder and other cancers in Taiwan by Dr ChienJen Chen and colleagues[18]. It appears that there were, and are, no data on humans to contest the idea that prolonged exposure to low doses is dangerous. But even then it took 10 years for everyone to respond. It is now realized that the catastrophe is much worse than the well known catastrophes of the Chernobyl nuclear power plant accident, the Bhopal isothiocyanate leak or the Kuwait oil fires. Yet for 30% of the Bangladeshi communities, pure water is still a long time away.

Dhaka Community Hospital

Dhaka Community Hospital was founded in 1988 and have 40 clinics dispersed throughout the countryside. DCH became involved with the arsenic problem in 1996 when DCH doctors working at an annual health camp at Pakshi, Pabna District first detected patients suffering symptoms of arsenicosis. DCH lobbied extensively to establish this issue as a public health problem and went on to work with Jadovpur University, Kolkata, India, to survey by sample the whole of Bangladesh. Since then DCH has collaborated with various partners in research into the problem and solutions for mitigation as well as conducting its own arsenic projects.

The choice between solutions

At the first International Conference held by Dhaka Community Hospital in January 1998 held jointly with Jadovpur University, Kolkata, several solutions to the problems were discussed. Either arsenic must be taken out of the water or an alternate solution must be found. There seemed to be some important criteria that any solution must satisfy:

(1) A short term solution might be acceptable if it was implemented on a wide scale at once.

(2) A long term solution should fit into a national water policy

(3) There was no reason for delay; short term solutions should be implemented at once.

If there was delay, the short term quickly became a long term.

(4) A simple return to unsanitary surface waters is undesirable

The proposal that was made at once was to have a national survey of wells, and install temporary arsenic removal devices. However 7 years later, there are many villages still without pure water. The arsenic removal devices proved too hard for many villagers to use and many of them were unsatisfactory and were abandoned[19]. Accordingly DCH has since 2000 been emphasizing longer-term solutions.

Two facets of an overall elimination of the Bangladesh arsenic problem seem to be agreed.

(a) There is no one solution for all places and communities. In some cases purifying the water

may be preferred; in others use of arsenic free water is easier.

(b) It is vital to involve the local community in the choice involved in the decision and even

more important in the follow up and maintenance.

(c) The solution in any community and location must be based upon the best possible scientific

understanding.

(d) Both anecdotal evidence and a detailed survey suggest that villagers are very interested in

running water in our near their houses and according to a recent survey seem to be more

willing to pay for it than running water than for arsenic free water. This makes it preferable

to use a solution which provides running water at the same time as pure water.

The solutions which meet these criteria seem to be:

1) Drilling deep wells (150+ m) to a deep aquifer, below a clay layer. Many hydrogeologists suggest that this aquifer is replenished by water from the mountains rather than annually from rainfall. The arsenic contamination of this deep layer is at present much smaller than the arsenic contamination of the ordinary tube wells at a depth of 40 meters. Although it is unclear whether it will always remain so. [20]

2) Encouraging a return to surface (dug) wells (DW), but with a strict adherence to WHO

sanitary standards.

3) Use of sand filters to filter pond water (PSF) or river water (RSF)

4) Storage of rain water

DCH chose the second of these, the use of dug wells, for this demonstration facility in the Pabna district. This report describes three phases of the work, and some indication of further development. Other groups are actively studying other solutions and we make no premature claim on which is superior.

The DCH Dug well Demonstration (Pilot) Project

The project was made possible by charitable donations from a number of foreign individuals and from the OPEC fund supplemented by locally generated funds. Although the project has begun somewhat earlier, it started in full measure in April 2002. In the first phase 39 wells were dug, (or in some cases reconditioned) by February 2003. These wells supplied 631 families and serving 3,250 users. Careful measurement was made of the bacterial content of each well. These wells were of different shapes and sizes, but all had in common the general sanitation features. They were sited remote from latrines. They were covered to prevent the entry of foreign matter, (animals, feces etc) and a small tube well and hand pump on the side extracts the water. During construction the well was properly sealed, the well was carried above a possible flood level, and a conrete apron was put just below the top to reduce ingress of water. The fundamental aim is to prevent ingress of water into the well, except the water that has been filtered through 30 feet of the surrounding soil. Chemicals (lime) were used in the initial installation and subsequent maintenance. In general WHO requirements were followed.[21] (See Appendix 1 for the detailed requirements recommended by DCH)

Bringing running Water to Houses

DCH noted that the Bangladesh government electrification program had already brought electricity to 50% of all villages and has the aim of bring electricity to them all by 2020. This makes it easy to install an electric pump to raise the water to a storage tank, from which it is gravity fed to a number (6 or more) individual houses. This has proved very popular and is a major step toward the acceptability of this solution. It is interesting that another grouphas found by survey that the availability of running water is more important in public perception than the fact that the water is arsenic free. Already in phase 1 one well was installed with a storage tank. In phase 2 seventeen new wells were dug and all had the pipeline system installed. Another 518 families were supplied and 2,903 users were served. In phase 3, nine old wells were renovated (brought up to WHO sanitary standards) and one new one dug; all with electric pump, storage tank and pipeline. This supplied another 400 families with 2,400 users. We believe that the positive experience with a pipeline system is a most important part of the demonstarion, pilot, project and we suggest that it will be an important part any solution to the arsenic problem since a pipeline system can be added, for exaple, to a centrally located deep tube well. Another grouop, the Bangladesh Arsenic Mitigation Water Supply Project (BAMWSP) has stated its intention of providing 30 pipeline systems[22] .