Despite stringent criticism directed at its safety standards, DDT still rules as the major pesticide used by India's health sector
Pest of a problem
MALARIA, the dreaded killer disease, is
staging a comeback with a vengeance.
Thought to have been controlled to a
large extent if not eradicated altogether,
its recurring presence today, has put a
formidable question mark on the methods used to eliminate it. The spotlight
has returned to the well-known but
controversial organochlorine pesticide
- dichloro diphenyl trichloro-ethane
(DDT) - which has been the mainstay of
the malaria eradication pi ogramme initiated by the states apart from malathion
and benzene hexachloride (BHC).
Although use of certain pesticides
are banned, withdrawn or
restricted in foreign countries, these very chemicals are
being used in India with little
thought to their safety
Aspects. DDT is one such insecticide whose use has been
enmeshed in controversy.
These insecticides have
been banned in most of the
developed countries, including UK, Australia, USA, Brazil,
Denmark, France and Sweden. The reason: it is virtually
non-degradable and therefore, highly stressful on the
environment. It is known to
settle in the far tissues in the
human body, and also cause
skin rashes and allergies. The
after-effects of this compound on the humanbody
include tremors, burning or
itching sensation, convulsions, joint pains, and liver
damage. Further, organo-chlorines are known to leave
residues in various living
organisms for prolonged
periods of their life spin.
Besides, it is known to have
disrupted reproductive systems of 'non-target' living
things found in remote parts
of the earth, like penguins in
M Antartica to deep ocean fish.
In India, around 1948, DDT -
whose properties as in insecticide well
discovered in 1939 by Paul Muller -
was introduced primarily as a deterrent
to crop pests. Other pesticides used for
crop protection include malathion, BHC,
endosulphan, aldrin and dicifol. DDT
made its entry in public health, specifically for the control of malaria Under
the National Malaria Control
Programme (NMCP) in 1953, This was
later extended towards the total eradication of malaria unclear the National
Malaria Eradication Programme (NMEP)
in 1958. When subsequent findings
on the ill-effects of DDT as a crop pesticide was made public, the Banerjee
Committee under the ministry of agriculture, in 1984 recommended its ban
in agriculture stating that while it could
be used in public health programmes,
its consumption should be limited to
10,000 metric tonnes per annum, subject to review. Eventually, the Use of DDT
in agriculture was banned from 1989.
Another high-level committee which
met in 1991, decided to maintain the
status quo on the use of DDT in the agricultural sector.
Despite the ban on DDT'S Use, it is
still widely being used in controlling
Pests like cotton pests in Andhra
Pradesh. This has alarmingly led to its
entry into the food chain and subsequent deposition in the adipose tissues of humans.
Haughtily dismissing this as
a matter for concern, A D
Pawar, secretary, Central
Insecticide Board and
National Registration Committee on pesticides, Faridabad, Says "DDT is banned in
agriculture and we have
washed our hands of it."
But this does not certainly cap the much-debated
issue. Malaria is still rampant
in many parts of the country.
A plethora of reasons can be
attributed to its strengthened
existence. The tropical climate of India offers an ideal
breeding ground for a host of
insects, mosquitoes and pests
which act as carriers of the
parasite protozoa. The problem is compounded with the
general lack of hygeine
among our people, especially, the poorer class.
Anopheles calicifacies proliferates in rural areas. Heaps of
uncollected rotting garbage
dotting the urban landscape,
poor drainage systems in
almost every state, water-
logged areas which exist even
after the monsoon is over
add to the misery. The urban thirst for more water storage Lanks,
coolers, wells and pumps have furthered
the growth of malarial vectors like
Anopheles stephensi. Says V P Sharma,
director, Malaria Research Centre, New
Delhi, "All these factors have caused the
malarial cases to increase radically."
There are serious doubts whether in
this existing scenario, DDTs usage is justified. "Definitely not,, argues P S
Sindbu, professor with the department
of chemistry, Delhi University,
"Though used for curbing
malaria, it has a negative effect
on the environment. After it
gets into the human food
chain, it harms the enzymes in
the liver." DDT has also outlived its usefulness as carrier
mosquitoes in several regions
have become immune to it.
Argues Sharma, "Malaria can
only be eradicated when there
is total people's participation.
As for DDT, it is the cheapest
and safest insecticide which
has saved millions of people
front death and all, made
development possible."
But the cost factor seems a
little too stretched to defend
the case of DDT. A T Dudani
- formerly with the
Voluntary Health Association
of India says a strict "no"
to the pesticide's use.
Staunchly anti DDT, Dudani
says that pest control should
involve only natural methods.
Echoing his view, Sharma
opines, "My first choice
Would be to practice biological-environemental methods like using
fish and bio-larvicides which will reduce
the bleeding of vectors, cleaning drams,
and chemical-impregnated bednets".
But since that these methods have yet to
actually take off, he recommends DDT
for the time being.
Hindustan Insecticides Limited
(UN) - the only public sector organisation manufacturing DDT in the country
is all for maintaining the status quo.
They still reckon the pesticide to be the
safest alternative for curbing malaria
vis-a-vis other substitutes,. Says a HIL official when asked to comment on
DDTs deleterious effects, "it has only
caused the thinning of the egg shells of
birds. How does that matter?" However,
tile NMEP which is facing flak for its
malaria eradication programme
going limp, is seeking to use the latest in the
market -- synthetic pyrethroids -
much to HIL's discomfort. These
pyrethroids, already used abroad, are
not only potent but also need to be used
in smaller doses. Recently, Maharashtra
switched to using delta metharine, a
synthetic pyrethroid replacing the Conventional DDT.
Says S Saluince, director
of the public health department in the
state, "If DDT needs to be sprayed once
every fortnight, delta metharine needs
to be sprayed only once every 12 to 14
weeks and has proved to be far more
effective than DDT in controlling the
mosquito menace."
Officials of HIL who were initially
tight-lipped over tile issue, said that the
change to synthetic pyrethroids will not
last long as cost-wise they are very
expensive. These chemicals are four
times more costlier than DDT. "How
long would the nearly Its 100-150 crore
budget to eradicate malaria last if only
synthetic pyrethiroids were to be used?,
questions P K Joshi, public relations
officer of HIL. Added S N Deshmukh,
chief, product development, HIL "Resistance development is a phenomenon
common to all pesticides and it will not
be long before mosquitoes develop
resistance to this also." Officials of the
Hoechst company who are pushing for
tile replacement of DDT with delta metharin, say that the pyrethroid need be
used only in small doses unlike DDT, and
will still prove to be more effective. Although the cost will be higher, Hoechst
officials vouch for the high degree of
safety that is attached with delta
metharie's application and speak highly of its potency and eco-friendly traits.
Another twist to The whole
story lies in the speculation
which is rife over DDT's carcinogenic properties. While
tests on mice revealed that it
could cause tumours, tests on
rats which have chromosome
patterns more similar to the
human physiological system
drew a blank. Lack of cogent
data on DDT's carcinogenic
tendencies shows that it is
pushed forward as the only
effective insecticide to curb
malaria by companies like
HIL. At the same time, it is
derided by the pro-synthetic
pyrethroid lobby consisting
mainly of chemical multinational giants like ICI-Zeneca,
Hoechst and Bayer.
But K Kanungo, joint
director, medical toxicology,
Central Insecticides Laboratorv, Fariclabad, says that "as
conducting human tests is not
possible, taking a chance by
Using DDT is not advisable'.
He advocates banning the pesticide and adopting synthetic
pyrethroids for, unlike DDT, "they are
easily bio-degradable and are safer".
According to him the main aim behind
the application of any pesticide should
be to prove toxic and fatal for the carrier insects, but least toxic to human
beings. Pyrethroids suit these specifications comfortably.
Meanwhile, the Union ministry of
health and family welfare has yet to
make Lip its mind over the possible
switch to synthetic pyrethroids. Resource crunch is cited as the main reason
for delaying the decision. But, saving
tile HIL from possible closure should not
be a criterion to persist with DDT's
usage, when the primary concern
should be to safeguard the health of the
people.
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