Home / Industry / IIT Madras develops nanoparticles to fight pesticide residues

Bangalore: In being one of the largest pesticide producers in Asia, India has made some mark in controlling pests, but in return has ruined its water resources. Even though nationwide data does not exist, isolated studies have started showing how groundwater and river systems are contaminated with pesticide residues, not removable by standard water filters.

Now, a team of researchers from IIT-Madras has developed nanoparticles that can eliminate one of the most difficult-to-remove class of chemicals in pesticides called organochlorine. Almost every organochlorine studied has been seen to cause some environmental or human health hazard and includes notorious pesticides like DDT, endosulfan, dioxin, HCH (hexachlorocyclohexane) and aldrin.

“Even though some of these pesticides have been banned, they are very much present in the environment. For instance, endosulfan has an environmental lifetime of 100 years," says T. Pradeep, professor of chemistry at IIT Madras. His nanoparticles, mostly from gold, silver, copper and several oxides, are effective on endosulfan even at very low concentration. “Efficient chemistry at low concentration is important so that even if one molecule of the pesticide passes by, it gets removed by the nanoparticle," adds Pradeep.

With an Indian and US patent in hand, Pradeep has licensed part of his work to Eureka Forbes Ltd, makers of vacuum cleaners and water purifiers, which in June 2007 introduced a novel nanosilver filter in some brands. “We wanted to productize and demonstrate our technology and create some excitement. So we took up initial industrial development at IIT," notes Pradeep. But any technology of this kind, he believes, needs to go the “real sufferers in rural areas". His current nanoparticles are effective on four most common organochlorine pesticides (OCPs) – DDT, endosulfan, malathion, and chlorpyrifos.

More than 40% pesticides used in India belong to the organochlorine category, known for their resistance to environmental degradation. There has been no national study yet but some patchy studies are being undertaken. For instance, a study by the Industrial Toxicological Research Centre (ITRC) in Lucknow published in the international journal Bulletin of Environmental Contamination and Toxicology in May 2007 shows high level residues of OCPs in fish from the Gomti River.

Another Council of Scientific and Industrial Research-commissioned study on groundwater sources by ITRC in Kanpur shows beyond permissible levels of DDT, HCH and endosulfan, according to Kunwar P. Singh, one of the lead researchers. A 2005-study on Ludhiana and Muktsar districts of Punjab, now expanded to other neighbouring regions, by the National Geophysical Research Institute (NGRI) in Hyderabad showed WHO-exceeding levels of OCPs like endosulfan, DDT, malathion and others. “We do not have national data; it’s only recently that the Department of Science and Tehcnology has initiated such studies," said Gurunadha Rao, a scientist at NGRI.

Ground efforts

Eureka is interested in taking this technology to rural population but the high cost of manufacturing could hinder the outreach for some time. “We intend to take this up as a no-loss, no-profit venture but that will have to wait until production goes up (and cost comes down)," says Abhay Kumar, general manager of water technologies division at Eureka in Bangalore. A community water purifier prototype, using nanotechnology filter, is under construction. It is scheduled to be installed in Kasargod district, one of the endosulfan-affected areas in Kerala, by March.

“This effort has to multiply, through all possible channels – industry, non-governmental organization and most importantly, government machinery," says Pradeep, whose interaction with the Central water resources ministry turned out to be a one-way affair. Under the US Clean Water Act of 1972, the extent of contaminants in a glass of water is decreasing, but the number of contaminants entering potable water is increasing, says Pradeep.

Experts believe eventually nanomaterial is the way to purify not only water but even ambient air indoors. “Many of these organics are extremely stable in the environment. Hence, chemistry of novel materials is the need," argues Pradeep.

Given India’s poor global ranking in drinking water quality (a 2003 UN report ranked India 120 among 122 nations in quality of water), the international aid agency World Vision India (WVI), headquartered in Hyderabad, is involved in some water purification progammes. “We are keen to find out how we can adapt this nanotechnology for rural masses," says Franklin Joseph, director, Humanitarian and Emergency Affairs.

WVI, which has a collaboration with Eureka, is now entering into an agreement with the Water and Process Technologies division of General Electric Company to use their reverse osmosis technology, suitable for removing salt and fluoride from water.

Pradeep’s group has also developed a pesticide test kit, slated to enter the market this year. One of the early proponents of nanotechnology for water purification when he came to IIT Madras 14 years ago from Purdue University in Indiana, US, Pradeep now has a slew of new nano materials that could free water from heavy metals like lead and mercury and other OCPs.

But his worry is: How do we develop a mechanism to take such technologies to the masses?

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