While residues of banned pesticides in the atmosphere are declining around the world India continues to have exceptionally high levels, a new study shows.
Portable samplers using chemically treated resin and deployed at several sites on seven continents from 2005 to 2008 showed that ‘organochlorine’ or chlorine-containing pesticides such as DDT (Dichloro-Diphenyl-Trichloroethane), chlordanes and endosuplhans (that also contains sulphur) are declining in most regions, suggesting the effect of worldwide bans.
But levels of organochlorine pesticides in India remain “exceptionally high”, researchers from the University of Toronto at Scarborough, Canada, reported in this month’s (September 2010) issue of Journal of Environmental Monitoring, published by the Royal Society of Chemistry.
For example, while the concentration of the pesticide ‘gamma HFC’ (hexachlorocyclohexane) is 0.3 nanograms (a nanogram is one-billionth of a gram) at Cape Grim in Australia, it is 800 nanograms in Delhi in India.
The findings suggest that though several harmful pesticides that persist in the air have been banned in the western world, there is still significant use in developing countries. An estimated 11 billion tonnes of pesticides are used each year worldwide.
Debi Sharma, senior scientist at the Indian Institute of Horticultural Research, Bangalore, told SciDev.Net that “it is common knowledge that in India the use of DDT is banned in agriculture but not for public health purposes.’’ Other pesticides such as aldrin, used against termites, conform to a ban imposed six years ago, he said. Studies by scientists at the National Institute of Occupational Health, Ahmedabad, published in the Bulletin of Environmental Contamination and Toxicology in 2004, showed that pesticides released into the environment entered living organisms, causing health problems. For example, endosulfan exposure delayed sexual maturity in boys and interfered with the production of male hormones.