Double indemnity
The US and other
developed countries banned the use of DDT in the ’70s because of its alarming
toxicity and possible carcinogenicity.
Despite the ban, India sprayed 7,000 tonnes of DDT in
2001-2002.
India has consumed 350,000 tonnes of DDT since 1985,
mainly for agricultural and public health purposes.
Studies reveal Indians have one of the highest body DDT
concentrations.
Intensive use of DDT has made mosquitoes resistant to the insecticide.
Dichlorodiphenyltrichloroethane (DDT) remains for the past three decades the
preferred method of malaria control in India. This is despite its ineffectiveness and
despite conclusive proof of mosquitoes showing triple resistance to the
insecticides–DDT, benzene hexachloride (BHC) and malathion.
Doubts remain over DDT’s safety and impact on the environment. In the
international arena, the DDT debate continues. In December 2001, the Stockholm convention
banned the use of the "dirty dozen", the 12 deadliest and most persistent
chemicals in the environment. DDT proved to be the most volatile and vexing
issue. Some countries demanded the immediate banning of DDT on account of its harmful
environmental and public health effects, while others supported its use in the control of
vector-borne diseases, particularly malaria.
Although the ineffectiveness of DDT is known, it is still being promoted. In countries
where DDT is effective, not banning its usage is understandable, but in the case of India
it is not. Arguments from pressure groups and malaria experts in India suggest that in
defending DDT’s continued usage, it is better to save people now from malaria than
worry about the deaths due to the poisonous insecticide in the long-run.
But need countries like India buy such an argument? Pro-DDT
groups push for its usage wherever malaria occurs. Others believe that persistent organic
pollutants (POPs) like DDT should be banned because they do not degrade easily, kill other
insect populations indiscriminately, and affect animals -- possibly humans -- as well.
Medicare or Malignancy?
During World War II, DDT was credited with having saved the
lives of 25 million soldiers by protecting them against malaria and typhus. This led to a
dramatic increase in the use of DDT after the war. World Health Organisation (WHO) and the
donor communities began depending on this stand-alone miracle compound to virtually
eliminate malaria, dengue fever and filariasis. Until resistance was observed, DDT helped
save millions of lives, especially in South East Asia, Latin America and India. In India,
the decline in deaths caused by malaria was very evident, from 10 million in 1953 to
2,85,962 in 1961.
 DDT’s tremendous promise in
controlling infectious diseases was questioned following the publication of Rachel
Carson’s book, "The Silent Spring", which startled the world on the
long-term effects of DDT. At a hot DDT debate in 1965, called the Madison Conference,
evidence was presented that pigeon and eagle populations were declining because birds
exposed to DDT were laying infertile and thin-shelled eggs. Resistance to DDT was also
observed in insects. In fish, the chemical was found to be highly toxic. Its chemical
stability and solubility in fat worsened the problem. DDT is not metabolised very rapidly
by animals. Instead, it is deposited and stored in the fatty tissues. If steady ingestion
continues, DDT builds up in the animal over time. In humans, the best indicator of
bioaccumulation is breast milk. Even Inuit mothers in the pristine Arctic environment have
traces of DDT in their breast milk and body fat!1
POP and India’s
stand
On May 23, 2001, India signed the convention banning the
use of 12 most dangerous Persistent Organic Pollutants (POPs). The convention decided that
the use of DDT would remain restricted to public health and be phased out once safer and
more viable alternatives are found. According to T R Baalu, union minister of environment
and forests, an urgent need to review the implications and ill effects of DDT is required.
Following the convention, a grant of $50,000 from the Global Environment Fund was provided
for the United Nations Industrial Development Organisation (UNIDO) to prepare a plan
within 6 months to tackle POPs. |
A Toxic trail
DDT persists in the environment long after killing insects,
and remains unaltered for years. Several studies, including one conducted by the Indian
Council of Medical Research (ICMR) in 1993, found alarmingly high levels of DDT,
hexachlorocyclohexane (HCH) and other extremely toxic pesticides in vegetables, fruits and
milk in Delhi, Maharashtra, Punjab, Andhra Pradesh and Uttar Pradesh. The average Indian
diet contains 0.27 mg of DDT.2 High levels of the pesticides have also been found in the
carcasses of buffaloes, the main food of vultures. This possibly may have contributed to
the disappearance of the ultimate scavenger.
DDT has in some cases been linked to the early onset of puberty.3 Studies indicate a
causative link of endocrine disruptors such as DDT to sexual precocity. In recent years,
elevated concentrations of diclorodiphenylethylene (DDE), a breakdown product of DDT, have
been associated with reduced lactation by mothers. Studies by K Senthil Kumar show that
the elusive dolphin in the Indian Ocean and other fish in the Ganga river have
extremely high concentrations of DDT and other pesticides (see box: Unholy Ganga).
But despite the mounting evidences, the joint
director of the National Anti Malaria Programme (NAMP), BR Thapar, maintains that DDT has
no ill effects. "No adverse effects on the human health have been observed so
far," he says. In 1994 (the year DDT was slated to be phased out of use in
agriculture), 300 Indian scientists proclaimed that DDT remains the best option for
control of pests.
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