Stratospheric Ozone Depletion and Regulation of Methyl Bromide

In the mid-1980s, some scientists became concerned that emissions of methyl bromide (MBr), a pesticide widely used in agriculture, could become a major source of bromine and thus could contribute to depleting the Earth's stratospheric ozone layer.The ozone layer shields the Earth's surface from harmful forms of ultraviolet radiation.MBr plays an important role in U.S. agricultural commerce because of its effectiveness in killing insects and plant pathogens.It is used extensively for pre-planting, postharvest, quarantine, and pre-shipping treatments.Production, consumption, and trade of MBr is regulated globally under the 1987 Montreal Protocol (on Substances That Deplete the Ozone Layer), amended in 1992 and adjusted in 1997, and domestically under Title VI of the U.S. Clean Air Act, amended in 1993 and in 1998.This report discusses regulation of MBr as an ozone-depleting substance and addresses possible concerns for Congress such as (1) the timing of a production phaseout, (2) "critical use" allowances, and (3) the search for alternatives.It will be updated as warranted.About 76,000 metric tons of methyl bromide (MBr) were manufactured globally in 1991 for agricultural uses.MBr is effective at killing molds, other fungi, insects, and worm (nematode) infestations of crops.About 80% of that tonnage is used as a fumigant to treat soils prior to planting.Another 20% is used to treat post-harvested commodities such as fruits, vegetables, dried foodstuffs, stored grains, cut flowers, and timber.Quarantine and pre-shipment (QPS) treatments for import/export account for about 1% of total tonnage produced.The profile of emissions differs for the various uses.About 50% of MBr is emitted into the atmosphere during pre-planting applications, while 80% can be emitted from QPS and post-harvest applications, if not in a contained environment.U.S. consumers of methyl bromide have petitioned Congress to amend the Clean Air Act (CAA) and extend its production phaseout from January 1, 2005, to January 1, 2015.They foresee higher costs, diminished supplies, lack of viable alternatives, and possible future restrictions on trade of U.S. agricultural products, if those cannot be treated with MBr.Congress extended the phaseout date once before.Acting under the authority of §604 of the CAA, on December 10, 1993, the U.S. Environmental Protection Agency (EPA) issued a final rule, freezing domestic production and consumption of MBr at 1991 CRS-2 1 "Protection of Stratospheric Ozone: Incorporation of CAA Amendments for reduction in Class-I, Group IV Substances (Environmental Protection Agency, 40 CFR Part 82), " Federal Register, v. 65 (Nov.28, 2000), 70795-70804.2 Article 5(1) refers to developing countries that consume less than 0.3 kg of ozone-depleting substances per capita.Non-Article 5(1) countries are industrialized or developed countries.Consumption equals tonnage for domestic uses plus imports of MBr, minus exports.3 For a definition of critical uses, see U.N. Environmental Program Ozone Secretariat, Draft Decision IX/1, "Further adjustments and amendments to the Montreal Protocol," and Decision IX/2: "Critical-use exemptions for methyl bromide" (UNEP/OzL.Pro.9/6,June 10, 1997).

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