ARSENIC PROBLEM IN BANGLADESH.
BACKGROUND:
Bangladesh is a small country with an area of 1, 47,570 square kilometers having a population of 130 million and it is very densely populated and it has an agrarian based economy and rural based human settlement. It is also a riverine country. Major part of the country is low lying and covered with fluvial, fluviodeltaic geomorphology; a large part of the country is being annually inundated and affected by devastating floods frequently. The country was famous from the ancient time for her water resources including the surface and near surface water. Before the advent of tube wells, the people used to depend on natural-surface water of rivers, cannels, lakes and man-made water reservoirs like ponds and ring wells. There are many water borne diseases for using surface water and tube well water has been thought to be safe for drinking and other domestic purposes. In Bangladesh nearly all the people are dependent on tube well water in the rural and small urban areas. Within two decades since 1970, people in Bangladesh have been found to be affected by arsenic toxication for drinking tube well water contaminated with arsenic. Arsenic contamination of ground water is now a hazard in Bangladesh. It has become a great concern for the people and the Government of the People’s Republic of Bangladesh as well as for the human communities abroad.
ARSENIC PROBLEM IDENTIFIED IN BAGLADESH
Although the cases of arsenic toxication and diseases have been known to physicians of the country since 1998, it was known in West Bengal of India since 1978 and specialists in Calcutta of West Bengal apprehended that similar problem of arsenic contamination of groundwater might occur in Bangladesh particularly in the areas adjoining to the areas of West Bengal. Presently, two theories about the arsenic poisoning in Bangladesh are known. In 1996, Dipankar Das, conducted a geochemical survey in the six districts of West Bengal bordering part of Bangladesh. These include Mulda, Murshidabad, Bardhaman, Nadia, North-24 Pargana and South-24 Pargana. They did a subsurface investigation, some laboratory analysis and observed the presence of arsenopyrite minerals in the sediments. They stated that the source of arsenic in groundwater and in the soil is form pyrite minerals containing arsenic. However, they did not discuss how arsenic is released in groundwater from arsenopyrite. A probable explanation may be that the changes of geochemical environment due to high withdrawal of groundwater might have resulted in the decomposition of pyrites to ferrous sulfate, ferric sulfate and sulfuric acid and thus arsenic in pyrites becomes available. In Bangladesh, a probable explanation is that the changes in geochemical environment due to the high withdrawal of groundwater resulted in the decomposition of pyrites to oxide of iron, arsenic, and sulfuric acid. The UK/DFID report mentioned that the oxidation of arsenic pyrite is not is a major cause of groundwater poisoning in Bangladesh rather they postulated an “arsenic adsorption and oxyhydroxide reduction” as the main cause of groundwater poisoning of Bangladesh. In Nawabganj, the clays near the surface are not enriched with arsenic to any greater extent than the clays below 150m. In other words, there is no evidence for the weathering and deposition of a discrete set of arsenic rich sediments at some particular time in the past. It is not clear yet how important these relatively arsenic rich sediments for providing arsenic to the adjacent, more permeable sandy aquifer horizons. There is unlikely to be a simple relationship between the arsenic content of the sediment and that of the water passing through it. The original source of arsenic probably existed as both sulfide and oxide minerals. Oxidation of pyrite in source areas and during sediment transport would have released soluble arsenic and sulfate. The sulfate would have been lost to the sea but the arsenic, as As(v), would subsequently have been absorbed by the secondary iron oxides formed. This is likely to be responsible for the greater contamination in the south and east of Bangladesh.
OFFSITE SOURCE OF ARSENIC CONTAMINATION
Bangladesh is located down gradient from West Bengal. During wet season the country receives huge amounts of surface water and pollution carried by rain water from the Indian subcontinent. The groundwater flow directions of major aquifers in the six districts of West Bengal are to the south and south eastern direction towards Bangladesh. Being located down gradient, Bangladesh receiving huge quantities of arsenic contaminated water from West Bengal. The migration of arsenic contaminated water from West Bengal to the Ganges delta of Bangladesh may have increased the concentration of arsenic in both soil and groundwater. A contribution factor to the groundwater arsenic poisoning in Bangladesh may have been India’s 23 years of unilateral diversion of water from the Ganges River due to the Farakka. In addition to the Farakka barrage, 17 dam/barrages that India has constructed may have significant influence on the arsenic and other environmental disasters in Bangladesh.
WHEN DID THE GROUNDWATER ARSENIC
POISONING IN BANGLADESH BEGIN:
During 1983 and 1987 Dr. K.C Shahs, Professor of Dermatology (retired) of School of Tropical Medicine, Calcutta conducted surveys in the seven districts of West Bengal of India. In 1983 Dr.Shaha identified patients poisoned by arsenic who had been drinking tube well water with concentration of arsenic range from (0.06-1.25) ppm and a mean concentration of 0.32ppm. According to Dr. Shaha’s survey the time required for the symptoms of arsenic poisoning to appear varies from six month to two years and is dependent on age.
In 1996 the Asian Arsenic Network (AAN) conducted skin examination on 167 people from the West Bengal of India who had drunk tube well water for a period of from 4 months to 45 years. Based on Dr. Shaha’s survey, the AAN estimated the beginning of arsenic contamination in West Bengal began around 1980-1981.No such survey is known to have been conducted in Bangladesh, however, in West Bengal we have seen evidence of poisoning after six months of drinking of arsenic contaminated water. A recent UK/DFID report states: There is clearly a very serious problem of arsenic in ground water in much of southern and eastern Bangladesh. In terms of population exposed Bangladesh has the most serious ground water arsenic poisoning problem in the world. There is little doubt that the origin of ground water arsenic poisoning in Bangladesh is geological but the UK/DFID statement on the age of the arsenic poisoning in ground water in Bangladesh contradicts the historical medical evidences. In 1999,Miah,M.A., University of Arkansas, U.S.A reported that prior to the 1970’s hundreds of thousands of people in 2800 villages of the Ganges Delta drink water from 280,000 hand-dug wells. If conditions were the same after the tube well were drilled as when the hang dug wells were used then the hang-dug well water would have been poisoning by arsenic in the same geologically contaminated areas where poisoning occurs today. If UK/DFID statement were true, then prior to 1965 the people who had been drinking hand-dug well water for hundreds of years would have certainly been poisoning by arsenic. Prior to 1975 there is no evidence that arsenic poisoning had affected people in Bangladesh, therefore, it appears that the ground water arsenic poisoning in Bangladesh is a recent environmental episode and began after 1975.The UK/DFID statement on the age of ground water arsenic poisoning in Bangladesh is not based on scientific facts but rather it is based on speculation.
AREAS OF ARSENIC CONTAMINATION IN
BANGLADESH:
It is reported that in the areas of forty four districts out of sixty four districts groundwater have been found to be affected by arsenic contamination. The districts are,
- : Rajshahi Division:
a) Nawabganj
b) Rajshahi
c) Natore
d) Pabna
e) Kurigram
- : Khulna Division:
a) Meherpur
b) Kustia
c) Chuadanga
d) Jenaidhh
e) Magura
f) Narail
g) Jessore
h) Satkhira
i) Bagerhat
j) Khulna
- : Dhaka Division:
a) Rajbari
b) Faridpur
c) Manikganj
d) Narayanganj
e) Narasangdi
f) Munshiganj
g) Madaripur
h) Shariatpur
i) Gopalganj
j) Netrakona
k) Gazipur
l) Kishoreganj
- : Barisal Division:
a) Pirospur
b) Jalakathi
c) Patuakhali
d) Bhola
e) Barishal
- : Chittagong Division:
a) Brahmanbaria
b) Comilla
c) Chandpur
d) Noakhali
e) Laxmipur
f) Feni
- Sylhet Division:
a) Sunamganj
b) Habiganj
c) Moulvi Bazar
d) Sylhet
It is important to mention the areas in West Bengal of India, which have been affected by arsenic contamination of groundwater. The arsenic affected areas are in districts of Malda, Murshidabad, Nadia, 24 Parganah North and 24 Parganah South.
OBJECTIVE:
The research I have conducted is aimed at determination of the level of arsenic in the groundwater and its impact on human health and environment (particularly soil and plants) in a village.
PURPOSE OF THE STUDY:
Arsenic problem in Bangladesh is a great natural and national calamity. It is a problem in the rural areas where about 80% of the people are living and where the tube wells supply water from the shallow aquifers has been found to be contaminated with arsenic. Day by day, the arsenic problem is increasing and one day the whole country will be affected and we will also see no arsenic free groundwater to drink. To highlight the fact to the related authority and take possible solution to overcome the problem I selected this matter. On the other hand, this matter also creating problem in the environment by,
a) Accumulation of arsenic on the surface soil decreasing soil fertility.
b) Accumulation of arsenic in plant
Because I deal with environment and protection of environment we should know the fact about arsenic.
BANGLADESH SCENARIO:
Contamination of groundwater in Bangladesh has already been accepted as the largest among the all incidents in the world and recognized as a worse disaster of this centaury for Bangladesh. Dhaka Community Hospital jointly with School of Environmental Studies (SOES), Jadavpur, West Bengal, India, randomly surveyed all 64 districts of Bangladesh. More than 25000 tube-well were tested by HG_AAS and detected more than 73% of the tube –wells contain arsenic more than 0.01 mg/l in 53 districts .About 23% of the tube-wells were containing arsenic more than 0.05 mg/l in 47districts.It is estimated that more than 50% million people are exposed arsenic more than 0.05mg/l of arsenic .Patients were identified by house to house visit from 32 districts. All though incidence of a arsenic induced manifestations were equally present in male and female but affected children were found about 1.75 in children were found about 17%. Much more tube-wells in Bangladesh are containing arsenic more than 1.00 mg/l than West Bengal.
In emergency arsenic mitigation program which is popularly known as Rapid Action Program (RAP) Dhaka Community Hospital surveyed 500 villages for identification of contaminated tube well and arsenic affected people along with some other information with the aim of mitigation. None of the villages were found arsenic free. Contamination of 5% to 95% was detected in the villages 0.3/1000 people were affected by arsenic. More than 97% of the Bangladeshi community is drinking water from about 9 to 10 million tube wells. Red ox condition of the Bangladesh soil has so far been made responsible for the contamination. So far nothing clear is known about its affect on human health and no known cure is available. Poor nutrition some times is made responsible to increase the susceptibility to inorganic arsenic but nothing is hundred percent. Only arsenic safe water can reverse symptoms at early stage. It is now essential for us to know the ill effect of arsenic effect human health and what could be possible rescue.
DESCRIPTION OF THE SITE:
Bangladesh has swiftly earned the reputation of being one of the most poisoned lands in the world as a result of arsenic contamination of groundwater. Tests have been carried out in almost all the districts of the country and no district or union has reported negative, meaning almost every district has at least some pockets which are arsenic affected. Out of the 64 districts, I selected the site which is situated in the PABNA district of the northern part of the country. A short description of my selected site is given below,
PABNA:
Administrator Location:
North: Natore and Sirajganj districts
South: Rajbari and Kustia districts
East: Manikganj and Sirajganj districts
West: Natore and Kustia districts
Area:
Total area is about 2, 37,150 square kilometers.
Environment:
The land of this district are classified into four part, those are,
a) Ganges delta plain
b) Korotoa delta plain
c) Jamuna delta plain
d) Barind tract
There are four rivers are present in this district, those are,
a) The Ganga
b) The Isamoti
c) The Gumani
d) The Hursagar
Metrological Data:
Average rainfall: 1872 mm.
Highest temperature: 33.90c
Lowest temperature: 9.60c
History:
Pabna district was formulated at 1832 and now is consisted of,
a) Upzilla: 9 (nine)
b) Pouroshova: 8 (eight)
c) Ward: 81 ( eighty one)
d) Moholla:191(one hundred ninety One)
e) Union: 72 ( seventy two)
f) Mouza: 1321 ( one thousand Twenty one)
g) Village: 1540 ( one thousand Forty)
Study Site:
My study site is situated in the “PABNA SADAR” Upzilla. A short description of “PABNA SADAR” is given below,
Administrator Location:
· Total area: 44,390 square kilometers
· North: Autghoria and Ishordi Upzilla
· South: Kustia sadar, Kumarkhali, Khoksha and
Pangsha Upzilla
· East: Sathia and Sujanagar Upzilla
· West: Ishordi Upzilla
Population:
· .24% Total: 4,31,531person
· Male: 51.76%
· Female: 48
Religion:
· Muslim: 97.10%
· Hindu: 2.85%
· Others: 0.05%
There is some other information which should be included,
*River: a) The Ganga
b) The Eshamoti
* Beel: Sonapatil
* Khal: Tarapasha
Location of the Site:
Administrative:
Village: Saradangi
Upzilla: Pabna sadar
District: Pabna
Geographical:
South: Raghunathpur (no arsenic)
North: Laxipur (no arsenic)
East: Brihispatipur (no arsenic)
West: Taziar para (no arsenic)
Socio-economic Condition:
A small scale socio-economic bench mark was carried out at the very first leg of my study. Majority of the households belong to a low cast Muslims. Some socio-economic parameters are highlighted below,
· Poor class: 170-200 family
· Middle class: 70-80 family
· Rich class: 40 family
These village people use surface and ground water for irrigation.
Population:
About 5000 (five thousands) people live in this village. The people of this village are involved in various professions, such as,
· Farmer
· Small trader
· Rickshwapuller
· Daylabour
· Service person
Religion:
· Muslim-98.25%
· Hindu-1.95%
· Others-0.80%
Sample Collection:
I have collected three types of samples. Those are water, plant and soil.
Water:
The water samples were collected in well-stoppered polyethylene containers and few drops of concentrated sulfuric acid were added into the sample for analyzing arsenic content. One photograph of water sample is given below,
Photo 1- Water sample
I have collected 10 (ten) samples of water from both of the arsenic affected and non affected areas that was previously tested by CCDB (Christian Commission of Development in Bangladesh).The CCDB conducted a survey on 161 tube wells at the Saradangi for the presence of arsenic during 2001. The CCDB found about 17 tube wells are affected out of 161. The 10 water sample I have collected are,
· 7(seven) from previously affected to determine if the affected level increase.
· 3(three) from non-affected tube well to find out
if these are newly affected.
Photo 2- An arsenic affected tube well (not use)
Laboratory Test:
The sample was send to the Intronics Technology Center (ITC) under the supervision of Dr. Mohammad Alauddin, Prof. Chemistry Dept., City Univ. of New York, USA. He applied different types of methods for examine the level of arsenic. Those are,
For Water:
The water sample was examined through the process of Hydride-Generation Atomic Absorption Spectrophotometry (HG-AAS).A simple description of the process is given below,
Diagram of HG-AAS
There are three bottles filled with sample, NH2OH and HCL. 5%KI or Ascorbic acid are mixed with the sample for pre-reduction of As5+ to As3+. The mixing substance of these three are than pass through a mixing coil and goes to a gas-liquid separator, where Ar (Argon) is inputted to produce Ash3 (Arsine gas).This gas is than pass through a Quartz-tube where C2H2 flame and air is given. The gas is than pass through Hollow Cathode Lamp to determine the arsenic level.
Result:
Water:
The result found in laboratory test of water from tube wells are given below,
| SL. NO. | SAMPLE ID | TUBE WELL OWNER | ARSENIC LEVEL (PPb) | ||
| 1 | S1 | Treated water | <1 | ||
| 2 | S2 | Abdul Aziz | 314 | ||
| 3 | S3 | Mr. Samad | 436 | ||
| 4 | S4 | Mr. Rafiq | 519 | ||
| 5 | S5 | Mobarok Sardar | 616 | ||
| 6 | S6 | Tasek Sarder | 216 | ||
| 7 | S7 | Moziuddin Khan | <1 | ||
| 8 | S8 | Riaj sarder | <1 | ||
| 9 | S9 | Mr. Mostofa | <1 | ||
Table1: Result of water sample
The S1 sample was collected from the treatment plant constructed by CCBD during 2001. The S2, S3, S4, S5 samples were collected form those tube wells that were affected (Previously tested by CCDB).Samples S7, S8and S9 samples were collected from those tube well that were not affected by arsenic tested by CCDB during 2001.
Analysis of water samples:
From the result we find that, arsenic is found in those samples which are already affected. That means the tube wells that were tested by CCDB in the year 2001 and found arsenic. In my testing I also found arsenic in those tube wells that are previously affected. No new affected tubes well are found.
Discussion:
From the above results we find that situation becoming worse because,
1) The level of arsenic is increasing day by day in the affected tube well though we did not find any newly affected tube well according to the CCDB report published in the 2001.
2) The number of person affected including visible and invisible is increasing day by day.
Groundwater concentration below 0.01 mg/l is considered safe according to World Health Organization (WHO) Drinking Water Guidelines. However, in the study area, the maximum permissible limit of arsenic in drinking water is 0.05 mg/l. we find that the arsenic concentration of tube wells were up to 616 ppb e.g. 0.6 mg/l which is very high and is becoming a major problem in that area day by day. So, we need to take some immediate steps for preventing the worse situation.
IMPACT OF ARSENIC ON THE SITE:
It is known that arsenic in soil and waters has some effects on plants and animals. The impacts mostly related to immediate effects following intake of bulk of arsenic at a time or long consumption of arsenic in smaller doses. Adverse effects of inorganic arsenic were better understood in nearly the end of 18th Century. Chronic intakes of arsenic in smaller doses were identified to produce skin pigmentation, hardening, cancer and other developmental damages.
Arsenic as a Toxic Element:
Arsenic (As) is a gray and brittle non-metal. It occurs in more than 250 arsenic minerals in the rocks. The red mineral realgar As2S2 and the yellow mineral orpiment As2S3 were known to the ancient (Olympiodors of fifth century).World Health Organization guide lines indicate safe level of arsenic content in the drinking water is 0.01 mg/l and Department of Environment of the Government of Bangladesh has suggested safe level of arsenic content is 0.05 mg/l in Bangladesh.
Biochemical effect of Arsenic:
Arsenic commonly occurs in insecticides, fungicides and herbicides. Among its compounds, those of As (III) are the most toxic.
As (III) exerts its toxic action by attacking SH group of an enzyme, thereby inhibiting enzyme action.
The enzymes which generate cellular energy in the citric acid cycle are adversely affected. The inhibitory action is based on inactivation of pyruvate dehydrogenase with As (III), whereby the generation of ATP is prevented.
By virtue of its chemical similarity to P, Arsenic interferes with some biochemical processes involving P. This is observed in the biochemical generation of the key energy-yielding substance, ATP (adenosine triphosphate). An important step in ATP generation is the enzymatic synthesis of 1, 3-diphosphoglycerate form glyceraldehydes 3-phosphate.Arsenite interferes by producing 1-arseno-3-phosphoglycerte instead of 1,3-diphosphoglycerte. Phosphorylation is replaced by arsenolysis which consists of spontaneous hydrolysis to 3-phosphoglycerate and arsenate.
Arsenic (III) compounds at high concentration coagulate proteins possibly by attacking the sulphur bonds maintaining the secondary and tertiary structures of proteins.
The three major biochemical actions of Arsenic are coagulation of proteins, complication with coenzymes and uncoupling of Phosphorylation.
The general antidotes for Arsenic poisoning are chemical having –SH groups capable of bonding to As (III), e.g.2, 3-dimercaptopropanol (BAL).
HSCH2—CH—CH2OH
Impact on Human:
In Bangladesh millions of people are drinking or will start drinking arsenic contaminated water and developing clinical manifestation leading to wide range of health hazard. Bangladesh incidence has already been recognized as the biggest incidence of chronic poisoning on the earth. Most of the cases have hypo or hyper pigmentation of skin and palmo-planter hardening (Keratosis). But cases of ulcers, gangrene, cancers and diseases of other systems are also there. It is quite alarming for our nation that about 7% children in our surveyed population had arsenicosis in comparison to 1.7% in a similar study in West Bengal. More than 90% of Bangladeshi community is drinking water from about 9 to 10 million tube wells. Red ox condition of the Bangladesh soil so far has been made responsible for contamination. Table below gives clinical manifestation of acute and chronic arsenic poisoning,
| System | Acute | Chronic |
| Dermatologic | Capillary flush, contact Dermatitis, hair-delayed loss | Melanosis, facial oedema, hyperkeratosis, palmoplanter, hyper pigmentation |
| Neurologic | Hyperpyrexia, disorientation | Headache, Axonal degen-eration |
| Gastrointestinal | Abdominal pain,Dysphagia vomiting and Diarrhea | Anorexia, weight loss, Jaundice |
| Renal | Tubular and Glomerular damage | Nephritic findings |
| Hematological | Anemia | Anemia Thrombocytopenia |
| Cardiovascular | ST-wave abnormalities arrhythmia | Acrocyacyanosis, Reynard’s gangrene |
| Respiratory | Pulmonary oedema, ARD,s, Bronchial pneumonia, Tracheobronchitis | Cough, Pulmonary fibrosis, Lung Cancer |
Table 2: Clinic-pathological findings in acute and chronic
Arsenic poisoning (Michael S. Gorby-arsenic in Environment)
The above table mentioned some name of the diseases that are happened because of arsenic poisoning. Some of these diseases are seen in my survey area. Table below indicate number of affected person and their symptoms in the study area,
| Owner of the
Affected tube Well |
Family
Member |
Number of
Affected Person |
Symptoms |
| Abdul Aziz | 8 | 1 | Skin rash in hand, weakness |
| Mr. Samad | 6 | 1 | Skin rash in hand and leg, ill health |
| Mr. Rafiq | 8 | 2 | Skin rash in whole body, the condition is severe; very weak |
| Mobarak
Sardar |
7 | 1 | Invisible symptoms but arsenic level in hair and nail are alarming according to the CCDB report |
| Tasek
Sarder |
6 | 2 | Skin rash in neck, hand and lower part of the feet; weak |
Table 3: Symptoms of the diseases due to arsenic
Source: Field Study
The photographs of the some affected persons are given below,
Photo 3- Tasek Sardar (arsenic affected person)
Photo 4- Hands of an arsenic person (skin rash)
IMPACT ON SOIL:
Soil is a major component of the environment. Because of presence of arsenic in the groundwater and its exposure to the surface of the earth soil become affected. The local people think that arsenic is distributed on their field because of throwing waste water of their bathing, washing and cooking. The local people also think that because of this arsenic, soil fertility is decreasing and according to their information every year the amount of production of crop is decreasing and they think that arsenic is responsible for this condition. Table is given below which shows the amount of crop production,
| Year | BR-11 per
Bigha (Mon) |
Aus per
Bigha (Mon) |
| 1998 | 17-16 | 8-9 |
| 1999 | 17-16 | 8-9 |
| 2000 | 16-15 | 7-8 |
| 2001 | 16-15 | 6-7 |
| 2002 | 15-14 | 6-7 |
Table 4: yearly crop production
Source: Field study
According to the interview with the local people they think that the shallow tube wells they are using for irrigation are arsenic affected. Because of the off season I was unable to collect water sample for testing. From my point of view we need more study about this matter to find out what actually happening.
IMPACT ON PLANT:
According to the laboratory test there are little amount of arsenic present in different parts of the collected plant. We need further study to find out what is the impact because of presence of arsenic in the plant.
MITIGATION MEASURE:
Arsenic is a poison in all its forms. Drinking water from tube wells, about 4 million, across Bangldesh, was once taken in good faith to be safe. Now this water has lead to a case of mass poisoning in view of the eventual wide spreading contamination of the country’s groundwater with arsenic. By one estimation, about 35 percent of the tube wells are unsafe, that is, they have arsenic concentration in excess of the current maximum contaminant level.
MITIGATION MEASURES TAKEN ON THE SITE:
In Bangladesh, a number of institutions, universities, government and non-government organizations and donor agencies are working on various aspect of arsenic contamination of groundwater. Several projects have been undertaken to understand the magnitude of the problem and adopt mitigation measures. Some of the projects are taken in my study site by CCDB as a mitigation measures for arsenic contamination. Two types of action are taken which are shortly describe below,
a) One water treatment plant was established in my study area by CCDB during the year of 2001 to provide arsenic free water for the people. The plant is Indian which cost about 70000(seventy thousands taka. The treatment plant provides arsenic free water for about 30 to 35 families of that area which are arsenic affected families. All the families are collecting only drinking water from this plant and for other purposes like bathing, dish washing they are using arsenic contaminated water.
b) The CCDB an non-governmental organization are providing some medical treatment by giving some medicines to the arsenic affected persons, such as, vitamin capsules and iron capsules etc.
Suggested Mitigated Measurer on the Study Site:
Though some mitigation measures are taken, from my point of view some other steps should be taken, for example,
a) Establishment of Standard Values for Arsenic in
Ground Water-
Since arsenic is found in all natural water, guideline values are needed to be established to delineate safe and unsafe water for water supply. Considering the wide spreading occurrences, scarcity of alternative safe water sources and technical capabilities in measurements and arsenic removal, the guideline values for Bangladesh may be recommended as follows:
Desirable Concentration———————- :< 0.01 mg/l
Maximum Allowable Concentration (MAC)–: 0.05 mg/l
Unsafe water————————————— :> 0.05 mg/l
b) Provision of Safe Drinking Water-
Supply of safe drinking water in the arsenic affected areas is urgently required to avoid further ingestion of arsenic and arsenic related diseases and to help recovery of affected patients. The possible options for the provision of safe drinking water include,
* Installation of tube wells in alternative aquifers producing water with low arsenic content. Sinking of deep tube wells is a promising option for water supply from uncontaminated deep aquifers having a protective overlying impermeable clay layer which is common in stratified aquifers in Bangladesh.
* Rainwater harvesting should be greatly encouraged as an alternative as well as supplementary water supply system in arsenic affected areas.
*Dug wells with adequate sanitary protection may be constructed for domestic water supply where aquifer and groundwater conditions permit such construction.
STRATEGIC PLAN FOR ARSENIC MITIGATION:
In the context of high prevalence of diarrhoeal diseases in Bangladesh, bacteriological quality received priority as a criterion for drinking water supply. Groundwater is free from pathogenic microorganisms and available in adequate quantity in shallow aquifers for the develoì¥Á5@
The magnitude of the problem is increasing as more information is pouring in. Arsenic in shallow tube well water has been detected in almost all districts in Bangladesh. According to the study conducted by the Department of Public Health Engineering and British Geological Survey(DPHE and BGS,2000), arsenic content of 46 percent of the shallow tube well water exceeds 0.01 mg/l( WHO guide line) and that of the 27 percent shallow tube wells exceeds 0.05 mg/l ( Bangladesh Standard). Extensive works would be required to understand the sources, causes, occurrences and distribution of arsenic contamination, health effect and health management, communication of health impact and finally development and implementation of safe water supply options in arsenic affected areas. Co-ordination of all initiatives in resolving this gigantic problem is needed for effective and efficient utilization of resources to attain the common goal. For example,
a) National survey-
The extent of arsenic problem is yet to be assessed. A national survey is required to understand the magnitude of the problem. A nation-wide survey should be conducted to achieve the following goals:
* Examination of the quality of water of all tube wells, starting with those in vulnerable areas in Bangladesh and identification of the tube wells producing water with high concentration of arsenic exceeding Bangladesh Standard and WHO Guideline value.
* Preparation of the maps showing the hot spots in respect of contamination of groundwater and prevalence of arsenic affected persons.
b) Awareness Building-
Awareness of the people about arsenic contamination of groundwater and related diseases is essential to combat arsenic problem in Bangladesh. People are to be made aware of,
* The possible health effects of drinking arsenic contaminated water as well as unsafe water from unprotected sources.
* Symptoms of arsenic contamination and possible places to seek help.
* Necessity of having the source of drinking water tested for arsenic and pathogens from a laboratory.
* Alternative sources of safe water and good hygienic practices to preserve quality of drinking water.
c) Building of Capacity through Training-
Appropriate and comprehensive training programs are to be developed with the following targets,
* Development of skills of the doctors and health workers to diagnose cases of arsenic poisoning.
* Enhancement of the knowledge and skills of the engineers, hydro geologist, NGO workers etc. to develop alternative safe water supply systems.
d) Establishment of National Database and information
Center-
Establishment of a national database and information centre for arsenic contamination of drinking water and resulting arsenic toxicity through proper documentation. It is considered as an effective tool for planning, designing and implementation of arsenic mitigation programs.
CONCLUSION:
Contamination of groundwater by arsenic is the product of complex geological and hydro geological processes and anthropological activities. Arsenic problem in Bangladesh is a great national and natural calamity. It is a problem in the rural areas where about 80% of the people are living and where the tube wells supply water from the shallow aquifers which have been found to be contaminated with arsenic. Many of the activities for arsenic mitigation plan are being implemented by the government and non-government organization, universities, research and training institutions and donor agencies under their own programs. Mobilization of concerted effort is needed to combat this public health problem of unprecedented magnitude. The Government of Bangladesh is yet to prepare a co-ordinated action plan and implement it for mitigation of arsenic problem in the country.
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