Order Code RS20863
Updated December 15, 2004
CRS Report for Congress
Received through the CRS Web
Stratospheric Ozone Depletion and
Regulation of Methyl Bromide
Wayne A. Morrissey
Science and Technology Information Analyst
Resources, Science, and Industry Division
Summary
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, post-
harvest, 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
Congressional Research Service ˜ The Library of Congress

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levels (about 62,000 metric tons), and ceasing its manufacture by January 1, 2001. In
1999, Congress extended U.S. production allowances until January 1, 2005 (§764(a) of
P.L. 105-277). Since then, prompted by H.R. 4125 and S. 2504, introduced in the 106th
Congress, the EPA issued a notice of proposed rulemaking to ban all domestic uses of
MBr by January 1, 2015.1 The rule would also halt manufacture by 2005, except for small
quantities for export to Article 5(1) countries,2 and for what they anticipated would
eventually be approved for “critical uses” under the Montreal Protocol on Substances That
Deplete the Ozone Layer.3 Presently, the CAA comports with international regulations
of MBr under the 1987 Montreal Protocol, as amended in 1992 and adjusted in 1997.
At a March 2004 meeting of Montreal Protocol parties, conflicts arose between
European Union negotiators, committed to a January 1, 2005, phaseout of MBr
production, and 13 industrialized countries that had requested allowances to produce
tonnage of it for “critical uses” after 2004. The United States requested the largest
allowances, including 39% (of 1991 production levels) for 2005, and 34% for 2006.4
Domestic concerns about regulating MBr as an ozone-depleting substance (ODS) have
included whether there is a need for stronger or less stringent controls of MBr emissions;
why production cutbacks scheduled under P.L. 105-277 were not met; and when, if ever,
effective alternatives for “critical uses” of MBr will be developed cost-effectively for U.S.
agricultural producers. Common questions have included:
! Do the economic benefits of MBr for U.S. produce growers outweigh its
potential danger to the ozone layer and health of humans and the environment?
! Is scientific evidence about MBr and stratospheric ozone depletion compelling
enough to justify stronger regulation, or any regulation at all?
! Were phaseout schedules under the CAA realistic, given the time it could take
to develop, approve, and market feasible alternatives?
! Can suitable chemical substitutes or alternative treatments be found for all of
its applications?
! Will it be necessary for farmers to stockpile MBr for “critical uses,” in case
Montreal Protocol parties cease allowances after 2006?
! Are there policy actions that can be taken now to reduce MBr emissions that
would minimize their potential depleting effects on the ozone layer?
Over the past two decades, the United Nations Environmental Program (UNEP) and
the U.N. World Meteorological Organization (WMO) have co-sponsored scientific,
technical, and economic studies containing in-depth analysis relating to the costs and
benefits of using MBr as an agricultural pesticide. These studies have attempted to
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).
4 Juliet Eilperin, “U.S. Gets Another Reprieve on Use of Pesticide by Farms,” Washington Post,
Nov. 27, 2004, p. A10.

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answer the questions above, and have been conducted at the request of Montreal Protocol
parties. Global government officials, science and agricultural agencies, chemical industry
producers of MBr, and agricultural consumers have advised such studies.
Scientific Research. Many scientists believe that diminishing ozone in Earth’s
stratosphere that traps UV-B radiation could increase incidences of skin cancer in humans
and animals, and produce genetic damage in terrestrial plants and marine phytoplankton,
possibly disrupting the natural food chains.5 Laboratory experiments conducted since the
discovery of the Antarctic Ozone Hole in the early 1980s showed that chlorine molecules
released from CFCs (chlorofluorocarbons), found in some industrial solvents and
refrigerants, and bromine molecules released from some fire extinguishing agents (halons)
were extremely effective at breaking down ozone molecules. They deduced that those
chemical reactions have serious implications for Earth’s stratospheric ozone layer.
On January 1, 1996, most manufacture and trade of CFCs and halons were banned
globally; however, CFC emissions are believed to remain in the atmosphere for 70-150
years, accounting for their high cumulative ozone depleting potential (ODP). Long before
then, scientists had turned their attention to methyl bromide, because of its suspected high
ODP.6 Research on MBr’s chemical reaction in the stratosphere was first reported outside
of the professional scientific literature in the UNEP 1991 Scientific Assessment of Ozone
Depletion. Some scientists cautioned that eventually MBr could become as significant
an environmental threat as CFCs and halons. Montreal Protocol parties and the EPA
accepted scientists’ estimates that MBr had a particularly strong ODP of 0.7.7 The 1994
Scientific Assessment of Ozone Depletion urged more stringent control on MBr emissions.
Although scientists had reported that the maximum ozone-depleting effects from
breakdown of a single MBr molecule occurred within two years, and had re-estimated its
ODP to fall within a range of 0.3-0.6, it continued to be regulated as a Class-I ODS.8
Four years later, UNEP’s 1998 Scientific Assessment of Ozone Depletion reported
about the findings of some scientists who suggested possible environmental benefits (e.g.,
quicker recovery of pre-ozone hole condition and lesser long-term exposure to UV-B
radiation) if concentrations of all ODSs in the stratosphere could be stabilized at 1999
levels. Reaping those benefits, UNEP noted, would require expeditious implementation
of the1997 “adjustments” to the Montreal Protocol, which included a more ambitious
phaseout schedule for MBr than in previous regulations. Under previous international
agreements, maximum ozone loss from all man-made ODSs emitted into the atmosphere
was projected to peak around 2030, and then slowly decline. However, by 1998, some
scientists observed concentrations of ozone in the upper stratosphere begin to increase,
5 “Surface UV Radiation,” Global Ozone Research and Monitoring Project — Report No. 37,
Scientific Assessment of Ozone Depletion: 1994 (WMO: Geneva, Feb. 1995), p. 9.1.
6 Class-I ozone-depleting substances have an ODP greater than 0.2, vis-a-vis CFC-11, which has
an ODP of 1.0.
7 Susan Solomon, A. R. Ravishankara, et al., “Atmospheric lifetimes and ozone depletion
potentials of methyl bromide (CH3Br) and Dibromoethane (CH2Br2),” Geophysical Research
Letters (19), Oct. 23, 1992, pp. 2059-2062.
8 “ODPs, GWPs and Cl-Br Loading,” UNEP/WMO Scientific Assessment of Ozone Depletion:
1994, p. 13.17.

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which many attributed to the 1996 global ban of CFCs and halons under the Montreal
Protocol. Many UNEP scientists were optimistic that concentrations of ODSs in the
stratosphere might actually peak as early as 2010, and pre-ozone hole conditions return
by 2050. Also, they theorized that if man-made emissions of MBr could cease, full
recovery could possibly occur 10 years sooner. Those findings had inspired some
Montreal Protocol parties to seek even more stringent regulations of MBr. Nevertheless,
the adjusted treaty would allow Article 5(1) countries to consume small quantities of MBr
until 2015. The possibility of an earlier peak of maximum depletion and evidence of a
recovering stratospheric ozone layer was viewed in some circles as evidence that the
Montreal Protocol (and CAA) was working.
In the 2002 UNEP Assessment, scientists reported difficulties in fully accounting for
all man-made and natural sources of and sinks of MBr emissions. They found that actual
quantities and apportionment of MBr in the environment were difficult to estimate,
because long-term measurements at probable sources were limited, or did not exist.
However, UNEP continued to sanction 1994 Assessment estimates that global agricultural
use accounted for nearly a third of all MBr emissions; other human-induced sources of
MBr, including biomass burning and automobile exhaust, might account for another third;
and out-gassing from the ocean was responsible to a lesser extent. Also, UNEP scientists
projected that by 2010, bromine released from MBr would constitute 30%-60% of ODSs
in the stratosphere; and, as concentrations of chlorine from CFCs and bromine from
halons declined, that of bromine release from MBr would increase 3% annually.
Economics and MBr Alternatives Studies. In 1994, the Montreal Protocol’s
Methyl Bromide Technical Options Committee released MBTOC-1, a report examining
possible alternatives for MBr in a number of different uses.9 That study mainly focused
on agricultural applications. It has since informed international negotiations regulating
emissions of manufactured MBr by suggesting possible options for global policy makers
to comply with the 1992 amendments to the Montreal Protocol that govern MBr
emissions. In addition, MBTOC-1 reviewed ongoing experimental studies of chemical
substitutes and alternative agricultural practices for its different applications. MBTOC-1
assumed that Montreal protocol parties would seek a rapid production phaseout, but also
considered possible exemptions for “emergency uses” of MBr, and recommended that
QPS treatments be exempted from regulation, pending longer-term studies of substitutes.
In 1998, MBTOC-2 was released. It urged Montreal Protocol parties to (1) identify
future critical uses of MBr; (2) inventory the quantities of MBr produced and consumed
globally; and (3) aggressively research alternatives for MBr’s use as a “soil fumigant, a
fumigant of durable commodities and structures ... and of perishable commodities.” Also,
it featured Article 5(1) country perspectives about a MBr phaseout; cited non-uniform
responses of pathogens to alternative treatments, geographically; and suggested possible
courses of action policy makers might take in the near term to reduce emissions, including
conservation and control measures, user fees, and research funding.10
9 U.S. interests on MBTOC are represented through such agencies as EPA, the National Oceanic
and Atmospheric Administration, the National Institute for Standards and Technology, the
National Aeronautics and Space Administration, and the USDA Agricultural Research Service.
10 EPA lists a range of substitutes for a variety of uses of methyl bromide on its website at
(continued...)

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MBr Regulations
Scientific findings about MBr’s possible potent ODP, presented in the UNEP’s 1991
Scientific Assessment of Ozone Depletion, spurred on the Natural Resources Defense
Council, Environmental Defense Fund, and Friends of the Earth to jointly petition EPA
to regulate MBr as a Class-I ODS under the CAA. (See “Scientific Research,” above.)
In March 1993, the EPA issued a notice of proposed rulemaking to add MBr to the CAA’s
lists of Class-I, under a new “schedule H,” created for MBr, which would require
regulation of its production and use.11 The EPA proposed to cap U.S. production of MBr
at 1991 levels by January 1, 1994, and to cease its manufacture December 31, 2000.12
In December 1995, parties to the 1985 U.N. Vienna Convention on Protection of the
Stratospheric Ozone Layer, the progenitor of the 1987 Montreal Protocol, convened for
the 10th meeting of Vienna Convention parties. Many were encouraged by news that the
atmospheric lifetime of MBr might be as short as two years, making it an easy target for
eradicating some ODSs in the stratosphere. They evaluated MBr’s existing phaseout
schedule and considered what actions would be necessary to stabilize concentrations of
MBr in the atmosphere.13 Over the following two years, Montreal Protocol parties
negotiated treaty text to “adjust” international regulations of MBr and expedite phaseout
of its production and use, globally. In September 1997, at the ninth meeting of Montreal
Protocol parties, a “final treaty text” was adopted whose terms obligated industrialized
countries to phase out production of MBr by January 1, 2005 — except for “critical uses”
under the MBTOC’s study. Interim reductions, based on 1991 production levels, were
scheduled for 25% by 1999, 50% by 2001, and 70% by 2003. Also, Article 5(1) countries
were obligated to cut 20% of average 1995-1998 consumption, beginning in 2005, and
cease its use by 2015.
Many U.S. produce growers and some U.S. lawmakers became concerned about
different phaseout requirements for MBr in industrialized and developing countries under
the adjusted Montreal Protocol, and under the CAA. Of particular concern were
consumption allowances for developing countries (some of which compete directly with
U.S. produce markets) that were granted until 2015, while domestic supplies declined.
Congress amended Title VI of the CAA in 1998, and extended the U.S. production
deadline for MBr to January 1, 2005, thereby securing parity with other industrialized
Montreal Protocol parties. In addition, it granted production allowances to U.S.
10 (...continued)
[http://www.epa.gov/docs/ozone/mbr/casestudies/index.html], visited on Dec. 13, 2004. The
Agricultural Research Service has its research results on alternatives for MBr on its website at
[http://www.ars.usda.gov/is/np/mba/apr04/], visited on Dec. 13, 2004.
11 “Protection of Stratospheric Ozone: Notice of Proposed Rule Making (Environmental
Protection Agency, 40 CFR Part 82),” Federal Register, v. 58 (Mar. 18, 1993), 15014-15038.
12 “Protection of Stratospheric Ozone, Final Rule Making (Environmental Protection Agency,
40 CFR Part 82),” Federal Register, v. 58 (Dec. 30, 1993), 69235-69238.
13 The original MBr regulations envisioned by Vienna Convention parties were not implemented.
For a summary of original terms, see “Statement by Nicholars Burns, Spokesman,” U.S.
Department of State, Office of the Spokesman, Press Release (Washington, DC: Dec. 7, 1995).

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manufacturers of MBr of up to 15% annually for export to Article 5(1) countries through
2015, thereby domestically implementing terms U.S. negotiators agreed to under the 1997
“adjustments” to the Montreal Protocol. Those regulatory changes discouraged
environmental groups that wanted an expeditious ban of MBr globally.
On January 3, 2003, EPA issued a final rule exempting quantities of MBr produced
for QPS treatment of agricultural commodities from regulation until January 1, 2005.14
In March 2003, the EPA solicited comments on a proposed rule to establish exemptions
for farmers’ “critical uses” of MBr beyond 2004.15 EPA initiated its “nomination of
critical uses” (NCU) in May 2003, having received 57 petitions from domestic consumers
who anticipated no economically feasible replacements for MBr by 2005. EPA either
approved, returned for additional information, or rejected them outright.16 It concluded
that about 23,000 lbs. of MBr would need to be manufactured for “critical uses” in the
2005 growing season alone.17 In November 2003, EPA submitted its final NCUs to
Montreal Protocol parties, requesting production allowances of 39% of 1991 tonnage for
2005 and 36% for 2006; decisions on NCUs were deferred until March 2004, however.
Uncertain about approval of its NCUs, some U.S. lawmakers threatened to withdraw
from the international treaty,18 when some parties questioned whether “what was being
sought was truly essential.”19 In June 2003, the House Science Energy and Air Quality
Subcommittee held a hearing on H.R. 3403, to amend the CAA and allow production of
MBr for “critical uses” after 2004, at EPA-approved levels, and extend 2005 allowances
annually through 2015.20 The bill saw no further action. In November 2004, Montreal
Protocol parties exempted 13 industrial countries from a 2005 MBr production ban. Final
U.S. allowances were 37% of 1991 tonnage; however, some parties warned that those
could be reduced to 27% in 2006, or the equivalent of 17,000 lbs.
14 “Process for Exempting Quarantine and Pre-Shipment Applications of Methyl Bromide:
Interim Final Rule.” Federal Register, v. 66 (Jul. 19, 2001), 37752-37769; Federal Register, v.
68 (Jan. 2, 2003), 237-254.
15 “Process for Exempting Critical Uses of Methyl Bromide ... Proposed Rule,” Federal Register,
v. 69(Aug. 25, 2004), 52366-52402.
16 “U.S. Government Nominates Critical Use Exemptions for Methyl Bromide,” Environmental
News, Feb. 7, 2003, at [http://www.epa.gov/spdpublc/mbr/], visited Dec. 10, 2004.
17 BNA, Inc., “Methyl Bromide Production for Export Can Continue Until 2005 under EPA
Rule,” Daily Environmental Report, vol. 82 (Apr. 29, 2002), p. A-6.
18 The Senate Committee on Foreign Relations considered Treaty Doc. 106-32, which restricted
international trade of MBr among Montreal Protocol parties by requiring a license for exporting
and importing, and approved that provision Oct. 2, 2002. U.S. withdrawal from the treaty would
result in loss of exporting privileges to other industrialized and Article 5(1) parties.
19 Andrew Revkin,”U.S. Seeks Exemptions for Pesticide, European Union Leads Critics as Ozone
Talks Open in Nairobi,” New York Times (Nov. 11, 2003), p. 3.
20 U.S. House Committee on Science, Subcommittee on Energy and Air Quality, Status of Methyl
Bromide under the Clean Air Act and the Montreal Protocol, hearing, June 3, 2003, available at
[http://energycommerce.house.gov], visited Dec. 10, 2004.

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