Published on Sunday, August 17, 2003 by the New York Times
Study Finds Atmospheric Decline in Pesticide Harmful to Ozone
by Andrew C. Revkin
Government scientists have measured a significant drop in atmospheric levels of methyl bromide, a versatile pesticide that is being phased out of use because it damages the planet's protective ozone layer.
The researchers, from the National Oceanic and Atmospheric Administration, describe the findings in yesterday's issue of the journal Geophysical Research Letters.
Methyl bromide, while less common than Freon and other restricted ozone-damaging substances, breaks down in the air and releases bromine, which disperses into the stratosphere and vigorously attacks ozone molecules.
But for decades methyl bromide has also been a popular, cheap means of sterilizing soils, grain silos and shipments of perishable goods.
Environmentalists welcomed the new findings but expressed concern about recent proposals by the United States and other countries to continue and expand certain uses of methyl bromide past 2005, when, under the Montreal pact, a ban is to take effect in industrialized countries.
This year the Bush administration is seeking exemptions to the ban on behalf of dozens of strawberry and tomato farmers, golf-course owners and other users of methyl bromide who say no inexpensive alternatives exist.
Federal agriculture officials also want to expand its use in fumigating imported wood packaging and shipping pallets that may contain Asian longhorn beetles or other pests.
But David D. Doniger, a policy director for the Natural Resources Defense Council, said the exemptions were unnecessary and would cause a rise in methyl bromide use after a steady drop. A variety of pesticides are listed by the federal government as substitutes for methyl bromide, Dr. Doniger said, adding that fumigation of imported goods could be ended if shippers were required to heat wood to kill pests or switch to other kinds of packaging.
The new study projects continued steep declines in methyl bromide in the air as long as use of the chemical continues to drop.
Those projections do not take into account the possibility of substantial use under exemptions to the Montreal treaty, said Dr. Stephen A. Montzka, the government chemist who led the study.
"Without continued worldwide adherence to the restrictions outlined in the protocol," Dr. Montzka said, "these trends could slow and delay the recovery of stratospheric ozone."
Copyright 2003 The New York Times Company