Arsenic contamination and Mitigation in Bangladesh

Arsenic contamination and Mitigation in Bangladesh: Role of DPHE

Introduction

Water supply in Bangladesh is predominately based on groundwater sources. In the context of very high prevalence of diarrhea 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 development of low cost tubewell based water supply for scattered rural population. Bangladesh achieved a remarkable success providing 97% of rural population with bacteriologically safe tubewell water. This was considered as the largest population coverage by safe water supply in the region. Water is universal solvent and capable of dissolving almost everything to a certain extent but the possibility of having arsenic at high concentration had never been considered seriously in the past. Unfortunately, arsenic contamination of shallow aquifers in many parts of the country has made shallow tubewell water unsafe for drinking.

Fundamental of Arsenic:

• Arsenic is widely distributed throughout the Earth’s crust, most often as arsenic sulfide or as metal arsenates and arsenides. It is the 20th most abundant element in the earth’s crust.
• Arsenic is introduced into drinking-water sources primarily through the dissolution of naturally occurring minerals and ores.
• Most important route of exposure is through the oral intake of food and beverages. There are a number of regions where arsenic may be present in drinking-water sources, particularly groundwater, at elevated concentrations.
• Arsenic in drinking-water is a significant cause of health effects in some areas, and arsenic is considered to be a high-priority substance for screening in drinking-water sources.
• Concentrations are often highly dependent on the depth to which the well is sunk.

Identification of Arsenic in Bangladesh:

• Arsenic in Tubewell water was first Identified in 1993.
• At Present Prevalence of Arsenic in Drinking Water has been identified in 61 out of 64 Districts of the Country. (Except, Hilly Districts)
• However the Degree of Contamination varies from 1% to over 90% with an average contamination of 29%.
• Arsenic in drinking-water is a significant cause of health effects in some areas, and arsenic is considered to be a high-priority substance for screening in drinking-water sources.
• In 268 (at present 271) out of 463 Upazilas of the country the Problem identified from the Survey of DPHE-UNICEF & DPHE-BGS (British Geological Survey). Survey of DPHE–UNICEF in 198 safe Upazilas identified 12 more Upazilas having arsenic problem.

Health Effect:

• Excess amount of Arsenic intake above the permissible limit in Human body makes Arsenicosis diseases.
• Maximum permissible limit for Bangladesh 0.05 mg/l
• WHO guideline value = 0.01 mg/l

Fact from WHO Guidelines

• Provisional guideline value 0.01 mg/litre (10 µg/litre). The guideline value is designated as provisional in view of the scientific uncertainties.
• Occurrence Levels in natural waters generally between 1 and 2 µg/litre, although concentrations may be elevated (up to 12 mg/litre) in areas containing natural sources.
• Basis of guideline: There remains considerable uncertainty over the actual risks at low derivation concentrations, and available data on mode of action do not provide a biological basis for using either linear or non-linear extrapolation
• Limit of detection 0.1 µg/litre by ICP/MS; 2 µg/litre by hydride generation AAS or FAAS
• Treatment achievability: It is technically feasible to achieve arsenic concentrations of 5 µg/litre or lower using any of several possible treatment methods. However,this requires careful process optimization and control, and a more reasonable expectation is that 10 mg/litre should be achievable by conventional treatment, e.g., coagulation.

Scale of the Problem:

• Mostly Shallow Tubewells are contaminated 29% of the sampled Tubewells are found contaminated nationally.
• Deep Tubewells (>150m depth) are generally safe.
• Survey findings indicated that irrigation is not the major cause of the Ground water Arsenic Problem (DPHE-BGS Study, 2000).
• 30-35 millions people are expected to be exposed to Arsenic contamination.
• The worst affected Districts:

Chandpur(90%), Noakhali(69%), Shriatpur(65%) , Munsiganj(83%),

Satkhira(67%), Meherpur(60%), Gopalganj(79%), Comilla(65%),

Bagerhat(60%), Madaripur(69%), Faridpur(65%), Laxmipur(56%)

Arsenic Mitigation activities by DPHE

• AwarenessBuilding.
• Testing of Tube well Water.
• Marking of Contaminated and Uncontaminated ube wells.
• Providing Alternative Water Supply Options.
• Patient Identification & Management

Awareness Building :

Disseminate Knowledge about arsenic posioning through multi-media channels.

• TV
• RADIO
• POSTER
• LEAF LET
• Inter Personal Comm.
• It is not contagious

National Screening Summary

Four Steps of Mitigation:

Alternate water supply option

The following option were identified as Arsenic mitigation option. These are categories as two group:

 a) Non Chemical

 b) chemical.

Non Chemical Option

Pond Sand filter : Treat pond water :

Oldest method to abstract water by digging a hole and using bucket with rope. Now it is upgraded by setting hand pump and covering the top of the well.

Mostly suitable in shallow depths above the contaminated aquifer. But it has a secondary risk of bacteriological contamination.

Dug well should be installed with safety from sanitation where deep tubewells are not successful.

Village Piped Water Supply

Surface water or Ground water source will be used. Existing Irrigation well which is arsenic safe can also be used where available .

Chemical option:

Surface water or Ground water source will be used. Existing Irrigation well which is arsenic safe can also be used where available.

Rapid Assessments of Arsenic Mitigation Option

• ITN-BUET conducted a health risk assessment of different non-chemical alternative options with the assistance of APSU, a DFID funded government project.
• Four options namely Dug well, PSF, Rain water Harvester and Deep Tube well were
• Microbiological contamination was very high in Dug wells and PSFs.
• More than 90% dug wells and PSFs were found to contain TTC
• Microbiological contamination was least in Deep tube wells.
• Only 8% Deep tube wells were found to contain TTC
• Microbiological contamination was found moderate in rain water harvesters.
• 40% – 60% rain water harvesters were found to contain TTC.
• No or very low chemical contamination was found in Rain water harvesters

DPHE Laboratories

Water quality testing is one of the major activities required before supplying safe water to its consumers. On this ground establishment of laboratories has been gaining increased attention day by day. The Development of laboratories in DPHE are summarized below:

1) In the early eighties, 4 Zonal laboratories were established at Rajshahi, Khulna, Comilla & Mymenshing with Dutch assistance.

2) One laboratory at Noakhali has been established with Danish assistance.

3) One laboratory at Jhenaidah has been established with Danish assistance.

4) Existing 4 zonal laboratories have been strengthened by renovating the physical infrastructures and supplying sophisticated equipment like Atomic Absorption Spectrophotometer (AAS) under the Bangladesh Arsenic Mitigation Water Supply Project (BAMWSP) funded by IDA and SDC.

5) 5 more Zonal Laboratories are being established at Dhaka, Barisal, Sylhet, Bogra and Rangpur with modern infrastructure facilities and sophisticated equipment liks AAS under the BAMWSP funded by IDA and SDC.

6) JICA has come up to establish a central laboratories for DPHE by constructing a modern laboratory building and equipping it with sophisticated facilities for water testing, which will act as coordinating & reference laboratory for all the laboratories of DPHE and will also administer training functions for the laboratory personnel.

7) JICA has also come up to renovate/Upgrade the two existing laboratories at Noakhali & Jhenaidah as Zonal Laboratories.

Policy and Strategy

Rural Water Supply

• Communities shall be the focus for all water supply activities; all other stakeholders including the private sector and NGOs shall provide coordinated inputs into the development of the sector with DPHE as the lead agency.Local government bodies in village, union and thana level shall have a direct role in planning, implementation and
• maintenance of rural water supply and the activities of public and private sector agencies will be coordinated accordingly.
• As water is increasingly considered to be an economic good as well as a social good, water supply services shall be provided based on user demand and cost-sharing. In the near future concerned communities shall share at least the following portions of costs: (a) 50% for hand tubewells in shallow water table areas, (b) 25% of hand tubewells in low water table areas, (c) 20% for deep hand tubewells and other technologies for different areas.
• User communities shall be responsible for operation and maintenance of water supply facilities and shall bear its total costs.
• Women shall be encouraged and supported to actively participate in decision making during planning, operation and maintenance.

The rural water supply program shall support and promote a range of technology options.

Urban Water Supply

• In order to make the water supply system sustainable water would be supplied at cost. However, educational and religious institutions will be provided with water as per existing government rules.
• In the future water tariff shall be determined on the basis of the cost of water production, operation and maintenance, administration and depreciation.
• Water supply and Sewerage Authorities (WASAs) shall be responsible for sustainable water supply in the metropolitan areas where WASAs exist while in other urban areas the Pourashabhas with the help of DPHE shall be responsible for the service.
• WASAs and Pourashabhas shall improve their operational efficiency including financial management.
• Private sector participation will be promoted.
• Monitoring of water quality for the purpose of ensuring an acceptable standard will be the responsibility of DPHE, DOE, BSTI, Atomic Energy Commission (AEC) and CBOs and they will send their reports to the water quality control committee in the Local Government Division.
• WASAs and relevant agencies shall support and promote any collective initiative in slums and squatters in accessing water supply services on payment.
• WASAs, DPHE, BUET and AEC shall conduct research and development activities for the development of appropriate technologies and other developments with special emphasis on difficult and under-served areas. They shall share the results of research and development and provide technical support to the private sector.
• Efforts shall be made to upgrade the capacity of the Pourashabhas and WASAs for planning, designing, implementation, management and human resource development and the DPHE shall have appropriate institutional linkage for this purpose.