| 1. First Detection |
Fluoride
contamination of ground water in the State of West
Bengal was first detected during 1997 at Nasipur
area of Nalhati-I Block in the district of Birbhum.
Very quick action was taken to provide an alternative
water supply arrangement based on river bed tubewells
(River Tripita).
|
| |
| 2. Occurrence of Fluoride in Ground Water |
| Fluoride is present in water
and higher concentrations are usually associated
with ground water. Highest natural level concentration
reported being 38.50 mg/l in Haryana. In India occurrence
of fluoride in ground water has been detected in
many places of Andhra Pradesh, Haryana, Jharkhand,
Tamilnadu, Karnataka, Gujarat, Rajhasthan, Maharashtra,
Madhya Pradesh, Chattisgarh, Punjab, Haryana, Uttar
Pradesh, Kerala, Orissa, Jammu & Kashmir, Bihar
and Delhi. In the recent past West Bengal and Assam
have been added in the list. Sporadic incidences
of high fluoride content in ground water have been
reported from China, Sri Lanka, West Indies, Spain,
Holland, Italy, Mexico, North and South American
countries also. |
| |
| 3. Health Effects |
India is among
23 Nations where health problems occur due to consumption
of fluoride contaminated water. Fluorine has been
found to be an essential element for animal species.
Once incorporated into teeth, fluorine reduces the
solubility of the enamel under acidic condition
and thereby provide protection against dental caries.
The incidence of caries decreases as the concentration
of fluoride increases to about 1 mg/l. Skeletal
fluorosis has been evidenced in persons when water
contains more than 3.60 mg/l of fluoride depending
on intake from other sources. Considering the climatic
condition and other related parameters, Bureau of
Indian Standards has prescribed fluoride concentrations
of 1 mg/l and 1.50 mg/l as desirable and permissible
limits respectively in respect of drinking water.
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|
| 4. Findings of GSI |
| As a follow up of the
reported very high incidence of fluoride contamination
of tube well waters of Nasipur area in Nalhati Block-I
of Birbhum District, GSI undertook a study during
1999-2000 covering an area of about 600 sq.km. with
the objective of finding out the extent of contaminated
ground water/surface water and possible source of
fluoride, if any, in different parts of the area.
It has been observed by GSI in its report (2002)
that the fluoride contaminated water occurs mostly
within tube wells tapping ground water within the
basaltic rocks of Rajmahal trap. Fluoride concentration
shows a wide range of variation between adjacent
areas or in nearby localities. The dug wells, ponds
and tube wells tapping water from alluvium sediments
are generally free from contamination beyond 1.50
mg/l. Thus, it is evident that geology, chemical
weathering and composition of bed rocks/soils/sediments
play a major role in fluoride contamination of ground
water, GSI has also observed in its report that
the Precambrian terrain with fractured/shear zones
are possible locale for fluoride contamination in
ground water in parts of Purulia and Bankura Districts. |
| |
| 5. Water
Quality Survey by PHED, West Bengal |
|
The Habitation Survey 2003
conducted by PHED reveals that occurrence of fluoride
in ground water beyond 1.50 mg/l in 46 Blocks in
8 districts is in a rather sporadic manner than
following a definite pattern. There are 166 Piped
Water Supply Schemes (PWSS) in these Blocks. Fluoride
concentration in excess of 1.50 mg/l has so far
been reported from :
(i)
Agacha Water Supply
Scheme in Kumarganj Block &
(ii)
Dhiltail Water Supply
Scheme in Bansihari Block of Dakshin Dinajpur District;
(iii)
Purandarpur Water Supply
Scheme in Suri-II Block &
(iv)
Matpalsa Water Supply Scheme in Sainthia Block of
Birbhum District. |
|
| 6. PHED
Actions so far |
| It has been possible
to sink new tube wells free of excess fluoride for
the first two schemes in the district of Dakshin Dianjpur
at suitable locations. For the last two schemes in
the district of Birbhum, water is being drawn from
riverbed tube wells (Bakreswar and Mayurakshi respectively). |
| |
| Some spot tube wells
of Rajpur-Sonarpur Municipality have shown excess
fluoride. The Municipality will receive water from
the South 24 Parganas Surface Water Project of PHED
as soon as the Municipality is ready with its infrastructure
to receive such water. |
| |
| 7. Plan of Action |
| A Fluoride Committee consisting
members from various organizations has been constituted
under the Public Health Engineering Department, Govt.
of West Bengal vide G.O. No. PHE/3241/3D-27/2003 dated
30.12.2003 with the objectives : |
| |
| 1. To co-ordinate and monitor
the different activities undertaken or being undertaken
by various authorities/organizations in the matter
or control of fluoride pollution in ground water. |
| 2. To draw up a master plan in
close liaison with the authorities/organizations and
to advise the State Govt. from time to time. |
| 3. To suggest for further research
if necessary. |
| 4. To recommend such other measures
as are considered necessary for removal of Fluoride
Contamination in drinking water derived from ground
water. |
 |
| The Fluoride Committee,
which comprises of experts from different Govt.
Organizations and Professional Institutes, decided
to conduct a Rapid Assessment of fluoride contamination
in ground water of West Bengal, to have a first
hand knowledge of the actual spread of the problem.
Accordingly, a list of 105 blocks in 12 districts
was prepared based on the previous test results
and the hydro-geological condition of vulnerable
areas. Water samples were collected from the designated
areas on random basis keeping due regard to the
geographical condition. As per the decision taken
by the Fluoride Committee, a Rapid Assessment of
Fluoride Contamination in Ground Water was taken
up with the assistance from UNICEF. Under this work
altogether 107 blocks in 12 districts were identified
which included blocks that appears vulnerable to
fluoride contamination and also some adjoining blocks. |
| |
| As per the findings of the
Rapid Assessment, 43 blocks of 7 districts namely
Birbhum, Bankura, Dakshin Dinajpur, Uttar Dinajpur,
Purulia, Malda and South 24 Paraganas were found
to have fluoride content beyond the maximum concentration
of 1.5 mg/l. A Joint Plan of Action in consultation
with the Fluoride Committee has been taken up with
UNICEF which encompasses complete testing of all
the public tubewells in the affected blocks and
take mitigation measures which may be summarized
as below : |
| |
| 1
Provision of alternate safe source in place of unsafe
sources. |
| 2.
Surface Water based Water Supply Schemes. |
| 3.
Hand Pump attached Fluoride Removal Plants. |
| 4.
Big Dia Tube well based Piped Water Supply Schemes. |
| 5.
Supply of water from traditional sources. |
| 6.
Rain Water Harvesting. |
| 7.
Household treatment. |
| 8.
Identification of Flurosis cases at early stage and
remedial measures. |
| 9.
Communication and awareness generation. |
| |
| Accordingly, the process of screening
tubewells in the 43 identified blocks have been initiated
by setting up of 9 new laboratories and strengthening
of 14 existing laboratories. |
| |
| As
water supply schemes based on sources other than ground
water is the best remedial action for mitigation of
fluoride contamination, a number of piped water supply
schemes have been identified wherever alternative
water from surface/ sub-surface flow is available
in the most vulnerable districts namely, Purulia,
Bankura, Birbhum and Dakshin Dinajpur. |
| 2004-2005 |
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