By 1967, endemic malaria was eradicated in developed countries and many subtropical Asian and Latin American countries. The 22nd World Health Assembly in 1969 ended the campaign because of lack of infrastructure to support Global eradication. Moreover, mosquitoes were becoming resistant to DDT.

During the 1970s, DDT was banned in many countries (Sweden 1970, USA 1972, UK 1986) mainly on the basis of ecological reasons like persistence in the environment and sufficient bio-accumulation and toxic effects that interfere with reproduction in pelagic birds. However toxic effects in human beings did not have a role in these bans. Adverse effects on human beings have been reported including neurological, carcinogenic (cancer causing), reproductive and developmental effects.

DDT is a very stable chemical compound. In the environment it breaks down to p,p/ – DDE which is an extremely stable compound that resists further environmental breakdown or metabolism by organisms. DDE is the form generally found in human tissue in the highest concentration. People are exposed to DDT mainly through food. Moreover DDT sprayers often wash their equipments in rivers and ponds. It is a dangerous practice since fishes consume large amount of DDT and by eating such fish, as well as by using the contaminated water, human beings consume it in high quantities too. On entering the body some amount of DDT is converted to DDA (Dichloro diphenyl Acetic Acid) and is excreted. But large amounts of it are  metabolised and the non metabolised DDT as well as any DDE produced is stored in fat since they are highly soluble in lipid.

The shelf life of DDE is about 7-11 years. Thus, over the years, DDT and DDE accumulates in the body to become permanent members of the system. The concentration of these two compounds increase with age.

DDT and DDE are transferred from women’s bodies to their children. Also the milk produced in their breasts contain high amount of these chemicals and the babies are exposed to it through breast milk too.

Health Risks :

Various studies have linked DDT with health problems. DDT is classified as a possible carcinogen (cancer causing substance) by the International Agency for Research on Cancer (IARC) and the US National Toxicology Program. Various studies done in India and abroad have established relationship between breast Cancer and p p/ - DDE (a metabolide of DDT). Some studies also link it to pancreatic cancer. DDT also affects human reproduction system. In women it is found to cause early menarche, early menopause and other problems related to menstrual cycle. It is also found to lower the probability of pregnancy. Data from the US Collaborative Perinatal Project as well as other studies indicated that DDE is correlated with the risk of spontaneous abortion. Spontaneous abortion (SAB) is the most common adverse pregnancy outcome and it affects around 15 % of all pregnancies. We have already mentioned the presence of DDT and DDE in breast milk. High DDE concentration in breast milk is found to be associated with shortened duration of lactation.

The program for International Student Assessment Study showed that high DDT concentration in human milk could be inversely associated with mental capacities at 15 years of age.

In May, 2001 the Stockholm Convention on Persistent Organic Pollutants (POPs) under the united Nations Environment Programme (UVEP) banned the use of nine internationally produced POP chemicals, mainly organochlorine pesticides, including DDT. However, it contains a condition in Annex B part II, a condition under which governments can be exempted from the ban on DDT use for the exclusive purpose of vector control. The ultimate goal of the convention is the complete elimination of DDT production and use, once affordable and effective alternatives are available. Partly due to six decades of excessive spraying resulting in physiological resistance, DDT has lost its effectiveness in malaria control. By the end of the Global Eradication campaign, some mosquito species had developed resistance to DDT, especially in India and Sri Lanka.

However, DDT is still widely used in India for malaria control.  In 1953 when 70 million cases and 0.8 million malaria death occurred, the National Malaria Control Programme was created. It was renamed the National Malaria Eradication Programme in 1958. Although NMEP believed that it can eradicate malaria in seven to nine years, the disease started re-appearing in 1965. Since then malaria rates in India rose gradually India to focus on control rather than eradication and in 1977 the modified plane of operation (MPO) was taken up which also comprised of the P. Falciparum Containment Programme (PFPC). The PFPC aimed to control falciparum malaria, the most commonly resistant and most deadly strain of the disease. However, there has been more epidemics and malaria deaths in the 1990’s. In 1994 there were large scale epidemic of Malaria throughout India.

Despite all the harmful effects and the proven ineffectiveness of DDT, it continues to be used for malaria control in developing countries like India. Currently 70% of all insecticides used in India are DDT and BHC (benzene hexachloride). Their use is increasing at a rate of 6 % a year in the country.

The argument mainly put forward in support of DDT is that in developing countries like India, alternatives to DDT are very costly and damages done by it are negligible compared to the lives it saves from malaria. But overwhelming scientific evidence says otherwise. We have already learned the harmful effects as well as extent of resistance shown by vectors against it. In this regard, we can consider what Dr. Walter J. Rogan and Dr. Aimin Chen of US National Institute of Environmental Health Sciences have to say – “Indoor residual spraying of DDT could be effective in some settings; the procedure is unlikely to lift the entire malaria mortality burden in infants and children. Additionally, if continuous DDT spraying does cause increased pre-term births and shortened breast-feeding duration, infant deaths will occur, perhaps to the same extent as the deaths spraying would potentially prevent. Mothers would also carry a body burden of DDT and even if they were to leave the malaria-protected house, they would still have raised risk of pre-term birth and early weaning. Other risks, such as neurological and reproductive effects in spraying staff, might also apply. (Health Risks and Benefits of DDT, Lancet 2005 ; 770)

Is there no other alternative to DDT in control of Malaria and other vector borne diseases? Scientists have found out that traditional health practices among some ancient tribes are very powerful against Malaria. We should also focus on proper research on such techniques.

It is unfortunate that despite its ineffectiveness in controlling malaria as well as its harmful side – effects, DDT is still the blue eyed boy of our policy makers. The same is the case with other harmful chemicals. According to an estimate of 1991, 13000 people die every year in India because of pesticides. While the tolerable limit of DDT in human body is 1.0 ppm, the usual average amount of DDT found in India people is 12.8 ppm to 31 ppm. According to a report of Indian Veterinary Research Institute the amount of DDT found in various food products in 1984-85 was 1 ppm to 8.01 ppm in India. While the US and other developed countries have banned DDT, the WHO has recently given a clean chit to the use of DDT in India. This turnaround is widely criticized all around the world.

Over reliance on any chemical is harmful for the environment. Many of the harmful chemicals banned in the developed countries are, however dumped in the developing countries. There are people in developed countries whose mantra of development for the developing countries is – ‘If trees are felled, the GDP will increase. If more people fall ill, sale of medicine will increase and it will eventually increase the GDP’. Such theories have some ardent buyers in the developing world. For these people environmental balance in something that is insignificant and unnecessary. High rise buildings and a roaring stock market is the only criteria for development for them. As most of our political leaders have little knowledge about environmental issues, there is not much emphasis on them. Besides, the governments of poor and developing countries. WHO’s clean chit to DDT for India and NMEP’s attempts to cover up the truth about DDT is indeed suspicious. Is there any secret pressure from big powers on the Indian policy makers ? This is question only time can answer. At the grassroot level, however, the people, especially those in media can create awareness about such things.

But the people of our country are not aware to such issues in general. The need of the hour, however, is to think seriously about alternatives to DDT as well as other harmful pesticides used in our country. Introduction of biopesticides or other environment friendly, modern alternatives can be expensive. It may increase the government expenditure and eventually can affect the lavish lifestyle of the elite. But again, don’t elites live in the same ecosystem that we do ?