Playing with poison

It is better to act early, than wait for ddt to take its toll on humans

 
Published: Sunday 31 October 1999

-- why haven't we banned ddt as yet. There are reasons enough to do so. Therefore, it is indeed surprising that the 115 nations that sat down to negotiate a ban on pesticides failed to ban ddt (dichloro diphynel trichloroethane). Perhaps, it is because ddt is used to fight malaria, a poor man's disease. Does this reflect a lack of concern on the part of the rich for the poor? Should the poor be only given cheap, but dangerous, alternatives in life?

Health, as stated by the World Health Organisation ( who ), is "not merely an absence of disease but a complete physical, social and political well-being". It is the physical and social well-being which ddt is directly going to affect, the reason why it has fallen out of favour in many countries across the world.

Classified as a "solid organochlorine insecticide" and a persistent organic pollutant because of its non-biodegradable properties, ddt concentrates in the fat tissues of the body from where it is slowly metabolised. Although the body slowly detoxifies and excretes them to the intestines, it gets reabsorbed because through enterohepatic circulation -- a mechanism by which the body conserves certain salts which are used to eliminate toxic materials.

But when ddt enters the food chain, its level keeps increasing through bioamplification . Gradually, it affects the nervous system by interfering with the neuronal membrane, and causes violent convulsions, uncontrollable seizures or may be just limited to myoclonic jerking (contraction of a group of muscles).

One of the functions of the liver is to maintain the internal milieu of the body, which it does by metabolising various hormones. ddt induces faster metabolism, thus producing an imbalance. That is not all. Various metabolites (any substance produced during metabolism) of ddt like ddd and dde also have far-reaching affects. It has been reported that though the ill-effects of dde is at a much lower concentration that ddt , it has a longer lifespan. It remains in the soil for over 190 years. The other metabolite, ddd, gets selectively concentrated in the adrenal glands where high level has inhibitory effect on the cells.

ddt also belongs to the family of pesticides, which mimic, block or interfere with the function of hormones. The human body has a very delicate chemical balance, which is maintained by the various hormones produced by endocrine glands. These glands control the functions of many other organs.

Studies have shown that, in rats, ddt disrupts the function of the male hormone, androgen, and have far-reaching effects on the development of a foetus. Also, there are confirmed reports of ddt adversely affecting animals. There have been several reports of ddt being responsible for the masculinsation of fishes, feminisation of birds, decrease in sperm count and infertility in rats.

Studies conducted in the us show that premature and underweight babies are likely to be born to mothers who are exposed to ddt . It has also been found that the length of lactation is inversely related to the level of ddt in the body.

ddt has also been shown to affect the immune system. Higher levels are associated within lower levels of white blood cells (the infection-fighting components of the blood). It reduces the ability of the cells to fight foreign microbes. Research has shown some of these effects to be transgenerational, that is it may even effect the foetus even though the father may not be exposed to the chemical.

Keeping all these things in mind it becomes all the more imperative to act at the earliest than wait for the effects to take its toll on us. We have to weigh our economic constrains against the health of our people. We are so many times accused for copying the West to our own peril, but some times it can be to our benefit.

There is no doubt that it is extremely difficult to label any chemical a carcinogenic substance, and this process takes decades. But the very fact that the who qualifies ddt to be a probable carcinogen should be taken note of by any country, including India, that has not banned the chemical use as yet.

The writer is a Delhi-based medical practitioner.

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