Methyl bromide, a fumigant that kills soil and food pests, is due to be phased out by developed nations by January 1, 2005, under the 1987 Montreal Protocol to protect the atmosphere.
The George W. Bush administration last year attempted to exempt farmers from the 2005 ban. Negotiations on how much should be exempted for critical uses deadlocked last November at a U.N.-sponsored negotiating conference in Nairobi. Delegates hope to reach an agreement on the figure at a Montreal meeting this week.
The United States, the European Union and Japan have cut the use of methyl bromide to 30 percent of 1991 levels, but now the United States wants to increase its use of the chemical to 37 percent over previous levels over the next two years and by an unspecified level in the year after that.
The protocol requires more than 180 signatory states to phase out the use of nearly 100 chemicals that damage the ozone layer, the part of the atmosphere that protects the Earth from ultraviolet radiation.
U.S. growers say they are concerned about a rule in the protocol that allows developing nations an extra 10 years, until 2015, before they have to phase out use of the pesticide.
\"The 50-acre grower in California may be competing with a multinational corporation based in China who gets to use the product 10 years longer,\" Rodger Wasson, president of the California Strawberry Commission, told Reuters in an interview.
Wasson said that puts U.S. growers at an unfair advantage because Chinese growers are now exporting frozen strawberries to the United States. Other U.S. growers say the chemical is necessary to compete with farmers in developing countries, such as Mexico, where labor costs for ridding crops of pests are much cheaper.
Environmentalists say giving exemptions to the Montreal Protocol could lead to a blow to widening global cooperation on other green pacts.
\"We need to see a commitment to a declining trajectory for methyl bromide. Otherwise we\'re left with a job unfinished,\" said U.N. Environment Program spokesman Nick Nuttall.
\"If this happens it may send the wrong signal and so other aspirations and goals like delivering safe and sufficient drinking water (in the Third World), reversing the loss of the world\'s wildlife, and fighting global warming can also be put on hold,\" he said.
Others say alternative fumigants that do not damage the ozone layer - including ProFume and Telone, both made by Dow AgroSciences, a subsidiary of Dow Chemical Co. - can be used in tomato and strawberry farms.
David Doniger, policy director at the U.S.-based advocacy group Natural Resources Defense Council, said methyl bromide is the most dangerous ozone-depleting chemical still in widespread use and also a cause of prostate cancer.
Other countries in the European Union are also asking for exemptions, but the U.S. is seeking more exemptions that the other countries combined.
(Additional reporting by Alister Doyle in Oslo)