Banned in US, but sold in India, found in mineral water

In the recent expose by Centre for Science and Environment on bottled water, 28 out of 34 samples showed the presence of this insecticide. Most brands had 100 times more residue than the European Union standards would allow.

It obviously means the compound is seeping into the underground aquifers and the bottled water companies have not been able to clean it. The presence of chlorpyrifos in water is surprising experts as it is considered to be ‘‘mildly’’ soluble.

This insecticide is a neuroteratogen, an agent that causes malformation in foetesus by inhibiting DNA synthesis. Any chemical that acts during pregnancy to produce a physical or functional defect in the child developing in the womb is called a teratogen. It is known to cause sterility in mammals over long periods of time.

An organophosphorous compound — a white crystal-like solid with a strong odour — it is becoming increasingly popular for controlling termites, cockroaches and white ants in urban areas.

Since it does not mix well with water, it is mixed with oily liquids, making it more soluble than it really is. Apart from what is used in farms, large quantities are put in the foundation while a building is being constructed. Interestingly, in 1997, chlorpyrifos was voluntary withdrawn from most indoor and pest uses by the manufacturer, DowElanco, in the US.

The US Environment Protection Agency is trying to phase it out by 2005.

In India, it is a different story: The demand for chlorpyrifos sold under various brand names has gone up from 1400 metric tonnes in 1995-96 to 7,500 metric tonnes in 1999-2000.

No estimates have been made as to how much is used in urban areas but according to unoffical estimates it’s nearly 70 per cent.

D-Nocil, which has its own formulation of chlorpyrifos for using against termites in houses, says the market for this product has grown rapidly in the past one year.

According to Central Insecticide Board, there are about 100 companies authorised to manufacture formulations of this compound.

‘‘Like every other pesticide, it is also being used more than necessary,’’ complains microbiologist A P Dudani, who has written a book called Aternatives to Pesticides.

It’s the sheer volume that’s wreaking havoc: in a plot of 15,000 square feet, 30 litres of the pesticide is used during the time of construction.

Whereas in a field of 2 acres, 2 litres would be used. Post-construction, the quantities depend on the extent of pest infestation and this estimate is made by the pest control firms listed dime a dozen in the yellow pages.

At times, it is injected by drilling a hole in the ground into the foundation of the building while at other times it is just sprayed or put on the woodwork.

What are the chances that it would seep into the groundwater table from the foundation of your house? ‘‘It is marginally safer than Aldrin as it is insoluble. That means it will stick to the soil.

But if the soil is sandy, it will enter the groundwater table,’’ says Adarsh Kumar, chemical scientist with Indraprastha University.

Otherwise, it stays for 10-100 days in the soil after which it breaks down into harmless compounds.

‘‘It’s solubility is 1.4 mg per litre, which means that it is likely that it will percolate with rainwater into the groundwater,’’ said M. Gopal, scientist with Indian Agriculture Research Institute’s chemical and pesticide department.

It is approved by the Central Insecticide Board and the quantities are to be regulated By BIS, but it is well known that they do not have the manpower to keep a check on contractors and private pest control companies.

‘‘This was so far considered to be a pesticide which is not under restricted use like DDT and Lindane in the country but the traces found in groundwater show that this too has to be looked at closely,’’ said Pranay Lal from Centre for Science and Environment.