| 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. |
|
| 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. |
| |
| As
per the decision taken by the Fluoride
Committee, a Rapid Assessment of Fluoride
Contamination in Ground Water has been
taken up with the assistance from UNICEF.
Under this work altogether 107
blocks in 12 districts have been identified
which includes blocks which appears vulnerable
to fluoride contamination and also some
adjoining blocks. |
| |
| As
per the decision taken by the committee,
from these blocks, representative water
samples have been collected at the rate
of one sample from each Gram Sansad.
So total volume of water
samples will be 18000 (approx.)
out of total 1,30,000 tube wells in 107
identified blocks. The water
samples will be tested in the B.E. College
laboratory and Birbhum district Water
Testing Laboratory. 5% of the water samples
will be cross checked at All India Institute
of Hygiene and Public Health. The
water samples are being collected by the
NGOs identified by the Zilla Parishad. |
| |
| A comprehensive
study report is expected to be completed
by 31st
August 2005. Future
course of action will be taken based on
this report.
|
