Arsenic is an element with metalloid property and is known for its toxicity. It is relatively soluble in water and occurs naturally in the environment. There are several hypotheses about the sources of arsenic contamination in groundwater of the Ganges delta region, and like most countries, it is thought to be geological. Studies have shown a high level of arsenic in pyrite (a type of rock) in the alluvial regions of Bangladesh. When groundwater is extracted, the pyrite is exposed to air and the arsenic becomes free and contaminates the water table. Thus, a high rate of water withdrawal by humans causes the problem of contamination.
Arsenic occurs in different forms, organic and inorganic, with different toxicity. Humans are exposed to arsenic mainly through eating, drinking and breathing. The World Health Organisation (WHO) has set 0.05 mg/L as the upper permissible limit for arsenic in drinking water. An excess of arsenic leads to serious human health problems. It may take 8-14 years after starting to drink arsenic-contaminated water for symptoms to appear. This period depends on the amount of arsenic ingested, the length of exposure and immunity level of the person. People with poor socio-economic and nutritional statuses are also more vulnerable to arsenic poisoning. Although arsenicosis, the disease caused by arsenic contamination, is not an infectious, contagious or hereditary disease, but it creates many social problems for the victims and their families.
In Bangladesh, the arsenic problem was first detected in 1993 at Barogharia union of Chapai Nawabgonj district and has been found to be quite extensive affecting most regions of the country. Most of the cases of arsenic poisoning appear to be caused by contamination of the tubewell water. More than 90 per cent of both rural and urban populations in Bangladesh depend on groundwater as a source of drinking water and are thus exposed to risks associated with arsenic contamination.
The issue of arsenic poisoning in groundwater in Bangladesh has received considerable attention from the media, government, non-governmental organisations and international agencies. BRAC works closely with the poor in improving their health, education and economic well-being. For example, BRAC has encouraged the use of sanitary latrines and hand tubewells as a source of drinking water. The discovery of arsenic in groundwater indicates that drinking tubewell water is no longer safe, particularly in areas where arsenic contamination is severe.
BRAC has initiated a programme on arsenic mitigation. It conducted two testing programmes to determine the nature, extent and magnitude of the problem. Firstly, tubewells in all of BRAC's 802 field offices were tested. Secondly, all the tubewells in one thana that was thought to be highly affected were tested. The testing programme was implemented in collaboration with the Department of Public Health and Engineering (DPHE) of the Government of Bangladesh.
The overall purpose of the BRAC arsenic programme is to mitigate the arsenic problem in any of the villages served by it that are affected. The broad objective of the testing programme was to determine the level of arsenic concentration in hand tubewells of all BRAC field offices across the country and all tubewells of Hajiganj thana, in order to develop a simple, inexpensive and rapid arsenic testing methodology.
The specific objectives of the testing programme were to: a) assess the capability of BRAC-trained village health workers in testing the tubewells in their own villages; b) test the reliability of the field kits used in ground water testing; and c) assess the capacity of BRAC in undertaking a large scale testing programme through its countrywide network.
Materials and Methods
For testing the tubewell water, Health Programme Organisers of BRAC and Shasthya Shebikas (village health workers or VHWs) were given two-day training on how to operate the field testing kit. The POs visited the field offices closest to their own stations and tested the tubewells located in those office premises. The VHWs based in the Hajiganj thana of Chandpur district tested water of all the tubewells in their own villages. VHWs are illiterate women who had earlier been trained by BRAC to treat selected common illnesses in the village. All the 156 villages of Hajiganj thana were distributed among the 40 VHWs who identified and tested all tubewells in their villages. They were also trained on what to advise the villagers if they tested any contaminated tubewells which included:
* Arsenic cannot be removed from water by boiling or by using normal filter.
* Arsenic cannot produce an infectious, contagious, or hereditary disease.
* Arsenic poisoning can be reversed by drinking arsenic-free water and by eating nutritious and vitamin-rich food.
* Increased use of surface water from rivers, ponds, canals, lakes, and rain water for all daily needs including those for agriculture should be encouraged.
* In areas where arsenic-free tubewell water is not available, river/pond/lake/dugwell water can be used for drinking after proper boiling. Or alternately, 70 per cent of the arsenic can be removed by keeping the arsenic-contaminated water in a pot for a least 12 hours and stirring the water three to four times with a piece of alum and then taking the upper 2/3 portions of the water.
Field kits promoted by National Institute of Preventive and Social Medicine (NIPSOM) in Dhaka were used for testing. This kit costs Tk 1,000 and can test up to 100 water samples. It was claimed to be user-friendly and able to detect arsenic contamination as low as 0.01 mg/L. Different reagents are used in the field kit procedure and the test is based on chemical reactions.
A total of 802 tubewell water samples were tested from BRAC offices and 11,954 were identified and tested in Hajiganj thana. From the latter, 193 water samples were selected randomly for further testing at the laboratories of the DPHE, Comilla, using spectrophotometre, and the results from two tests (viz, the field kits and spectrophotometre) were subsequently matched.
The Tubewells of BRAC Field Offices: Of the 802 field offices of BRAC, tubewell water of 94 offices (12 per cent) were found to be contaminated with arsenic. Examination of the status of arsenic in tubewells of BRAC offices by region shows that proportion of tubewells found contaminated was more in the south of the country. Out of 61 districts from which data was available, arsenic was found in 34 districts.
The Tubewells of Hajiganj: Out of the total of 11,954 tubewells at Hajiganj thana, arsenic concentration in 859 tubewells were found to be within the acceptable limit set by WHO. The remaining 11,096 or 93 per cent tubewells were found to be contaminated with arsenic concentration greater than the acceptable limit. In two of the 11 unions, over 99 per cent of the tubewells were contaminated. When the test results were examined by village, the percentage of villages where all tubewells were contaminated was 53. In other words, 53 per cent of the villages had no access to safewater.
A strong relationship was found to exist between depth of the tubewell and arsenic contamination. Very deep tubewells (100 feet or more) and shallow tubewells (less than 50 feet) were less likely to be contaminated.
A total of 193 randomly selected water samples from Hajiganj were analysed
by spectrophotometre to determine the validity of the field kit results
and they were found to agree in 178 of the cases or 92 per cent. Results
of arsenic testing by spectrophotometre indicated the presence of a high
level of arsenic concentration in the hand tubewells of Hajiganj thana.
Only 8 per cent had arsenic content which is considered safe (<- 0.05
mg/L). Sixty four tubewells (33 per cent) had contamination of over 0.25
mg/L, which is alarmingly high.
|Summary of test results from Hajiganj thana|
|Total population of the thana||254,057|
|Number of unions||11|
|Number of villages||156|
|Number of tubewells tested by field kit||11,954|
|Number of tubewells contaminated with arsenic||11,095 (93 per cent)|
|Number of villages with all tubewells contaminated||83 (53 per cent)|
|Number of samples tested by spectrophotometer||193|
|Field test results confirmed by spectrophotometer (per cent cases)||92|
Time and Cost: The fieldwork in Hajiganj was undertaken between 23 November and 23 December 1997. A total of 45 VHWs and volunteers took part in the operation, each testing 20-25 tubewells per day.
An important objective of this programme was to accomplish the testing at an affordable cost. An average of Tk 18 was spent to test each tubewell for arsenic contamination. VHWs and volunteers were paid Tk 50 per work day.
The source of arsenic contamination is considered to be geological, and a result of high withdrawal of underground water. In Bangladesh most of the drinking water is tapped from groundwater with deep and shallow tubewells. There are more than 2.5 million such tubewells in the rural areas, covering 95 per cent of the total population. The indiscriminate use of groundwater for irrigation, lack of proper water management, and inadequate recharge of the aquifer is believed to have led to the progressive decline of ground water all over the country. As a result, the arsenic problem in Bangladesh is growing very rapidly and appears to be a threat to public health, and was confirmed by this study. It is a matter of grave concern particularly for specific affected areas such as Hajiganj. To mitigate this problem in Bangladesh, rapid detection of arsenic-contaminated tubewells, provision of safewater, treatment of affected persons and health awareness in the community is essential. There is a no user-friendly, low cost, and simple method available for arsenic removal. The detection of arsenic contaminated tubewells and provision of arsenic related information appear to be critical in the present situation.
The number of tubewells to be tested is very large, necessitating development of a simple, low cost, low key, and community acceptable system of tubewell testing. BRAC has shown that rural illiterate women can effectively be trained to carry out testing of tubewells in their own villages very quickly and at a reasonably low cost.
The other advantage of involving the community in this task is the creation of awareness about the problem, as a by-product of the testing programme itself. It is expected that a mitigation programme, if implemented following such testing, will have high success rate.
Several field kits for arsenic testing are available in Bangladesh. The field kit used in the present research was cheap, easy-to-handle and gave reasonably accurate results. Continuous monitoring of the kit itself and the reagent used in this process must, however, be ensured.
NGOs are working closely with community people, meeting and interacting on a regular basis to implement various programmes and disseminate related messages. For example, BRAC workers meet with 2.2 million women, representing the same number of families, every week. Messages on arsenic and arsenic hazards can easily be transmitted through such network. These networks also offer the potential for effective implementation of any mitigation programme. BRAC has worked with the Department of Public Health and Engineering (DPHE) of the government in this testing experiment which shows that effective collaboration between the government and NGOs can be forged to address a huge problem such as the arsenic contamination in tubewell water in Bangladesh.
The authors are staff members of BRAC. They are grateful to a large number of individuals for help in this work, particularly Mr. Aminul Alam, Dr. KMA Aziz, Ms. Emma Child and other staff members of BRAC in the field.