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US pushes limits on ozone destroyer

December 2, 2005 By Charlotte Schubert This article courtesy of Nature News.

It seems that methyl bromide cannot be phased out as a pesticide yet.

The United States is spearheading calls for the continued use of methyl bromide as a pesticide. Methyl bromide is the last ozone-depleting chemical remaining in widespread use and it was due to be phased out completely in developed countries this year.

Under the terms of the 1987 Montreal Protocol, countries agreed to remove from use several chemicals that attack the ozone layer. But when parties to the treaty meet on 12 December in Dakar, Senegal, delegates will consider a US request to use more than 6,500 tonnes of methyl bromide during 2007. North America uses more of the substance than anywhere in the world, mostly as a pesticide on strawberries, tomatoes and other crops.

Other countries, including Australia and Japan, have also asked for exemptions in the past, but the United States has led the pack: its requests for 2005 use are more than all others combined.

Under pressure

It's the first serious effort to break out of the treaty.
David Doniger
policy director at the US Natural Resources Defense Council
To some, such outsized requests reflect US capitulation to pressure from farming groups and methyl bromide manufacturers.

"It's the first serious effort to break out of the treaty," says David Doniger, a policy director at the Natural Resources Defense Council (NRDC) in Washington DC. Doniger is heading a lawsuit against the US Environmental Protection Agency for failing to comply with parts of the treaty.

But representatives of the farming industry counter that the huge value of the crops, and the efficiency of methyl bromide as a pesticide, means that its continued use is reasonable.

"There just are not perfect substitutes at this point," says James Elkins, an atmospheric physicist at the National Oceanic and Atmospheric Administration in Boulder, Colorado. "But we could use the decrease to help the atmosphere recover and so it's kind of a tug of war."

Clearing skies

Methyl bromide is particularly damaging, says Elkins. In the stratosphere, it breaks down and releases bromine, which destroys ozone and allows the Sun's ultraviolet rays to penetrate the atmosphere more easily. Bromine is 45 times more damaging than chlorine, which is released from infamous ozone-depleting substances such as chlorofluorocarbons (CFCs).

But methyl bromide persists in the atmosphere for only a year, compared with 50-100 years for CFCs. Consumption of methyl bromide has been cut by more than half since 1991, the baseline year for the treaty, and Elkin says that these measures have already had a detectable effect on the atmosphere.

Unfair claims

This year, US exemption requests went down a few percentage points after negotiation, and they are decreasing overall. But the country is still riling others at the table.

"We are very concerned that the playing field is not level between the United States and other parties," says Tom Batchelor, a policy officer at the European Commission in Brussels. He says the United States had requested permission to use more methyl bromide in 2005 than it consumed in 2003, "in effect a phase-in rather than a phase-out."

Europe was given permission to use 4400 tonnes of methyl bromide in 2005, but according to Batchelor an internal review got the actual amount used to less than 3,000 tonnes. "We don't see the United States going through the same rigorous evaluation system."

Claudia McMurray, the US deputy assistant environment secretary, admits there has been friction. "But the US is getting very good at making its technical case," she adds.


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