United States Office of Pesticides and Toxic Substances
Environmental Protection • Office of Pesticide Programs (TS-766C)
Agency Washington, DC 20460
&EPA Pesticide
Fact Sheet
Name of Chemical: Methyl Bromide
Reason for Issuance: Registration Standard
Date Issued: August 22, 1986
Fact Sheet Number: 98
1. Description of Chemical
Generic Name: Bromomethane
Common Name. Methyl Bromide
Trade Names Brom-0-Gas*"; Celfume®; Dowfume®; Embafume®, Kayafume®;
Meth-0 Gas®; Terr-0-Gas 100®
EPA/OPP Pesticide Chemical Code: 053201
Chemical Abstracts Service (CAS) Number: 74-83-9
Year of Initial Registration 1961
Pesticide Type. Acaricide; Fungicide; Herbicide; Insecticide; Nematicide;
Rodentlcide
Chemical Family Halogenated Hydrocarbons
U.S. and Foreign Producers: Great Lakes Chemical Corporation;
Ethyl Corporation; Ameribrom, Inc.
2. Use Patterns and Formulations
Application Sites: Agricultural crops; ornamentals; soil, manure,
mulch and compost fumigation; stored commodities (both raw agricultural
commodities and processed foods/feeds); greenhouses; homes; grain
elevators; mills; ships and transportation vehicles.
Types of Formulations: Gaseous, liquid under pressure, or liquid.
Types and Methods of Application: Chisel application to field soil;
gravity distribution for smaller bins; forced (recirculation)
distribution systems, tarpaulin.
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Application Rates: For stored product pests infesting raw agricultural
commodities dosage rates are between 2-6 lbs/l000 Cu. ft. with exposure
times ranging from 12—24 hours for nuts and grains and from 2—4 hours
for other commodities; for processed foods, dosage rates are between
1—3 lbs/1000 cu. ft. with exposure times ranging from 12—24 hours
for soil fumigation uses, dosage rates are between 180—870 lbs/A
depending on the type of application with exposure times ranging from
24—48 hours; for structural pest control, dosage rates are between
1—3 lbs/1000 cu. ft. with exposure times ranging from 2—24 hours for
insects and 12—18 hours for mice and rats.
Usual Carriers: None
3. Science Find gs
Although methyl bromide has been widely used for many years, its
chronic toxicity has not been adequately characterized. Uncertainty
also exists in the areas of dietary exposure, applicator exposure,
and groundwater contamination.
Chemical Characteristics:
Physical State. Gaseous, liquid under pressure
Odor: Odorless
Boiling Point 4°C
Melting Point: —94°C
Flash Point Nonflammable
Unusual Handling Characteristics: Non corrosive to metal containers;
however, traces of water or acid may lead to corrosion of application
equipment
Toxicology Characteristics:
Acute Oral Toxicity: Toxicity Category II; ‘ so in the rat is 214 mg/kg
Acute Inhalation Toxicity: Toxicity Category I based on human experience
and use history; LD 50 is 2700 ppm for a 30 minute exposure in the rat;
in humans, 1,583 ppm (6.2 mg/i) was lethal to adults exposed for 10—20
hours while 7,890 ppm (30.9 mg/i) was lethal after 1 1/2 hours.
Primary Eye Irritation: Toxicity Category I; Corrosive
Primary Skin Irritation: Toxicity Category I; Corrosive
Major Route of Exposure: Inhalation
Problems which are known to have occurred with use of methyl bromide:
In California, methyl bromide ranks seventh in terms of systemic
poisonings, second in terms of number of people hospitalized and
first in terms of number of days hospitalized for 1982—1985.
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The chronic and subchronic toxicity data base is limited. A teratogenicity
study in the rat and several mutagenicity studies are negative. Under the
Data Call—In Program for Grain Fumigants, reproduction and oncogenicity
studies were required. Preliminary results of these studies indicate
that they are both negative. Mutagenicity, rabbit teratology, subchronic
inhalation in the rat and rabbit, and chronic feeding studies in the
rat and dog are required to complete the toxicology data base for
methyl bromide.
Physiological and Biochemical Behavioral Characteristics: N/A
Environmental Characteristics:
Bydrolysis data indicate that methyl bromide breaks down at a rate of
1.4 mg/liter water/day at 25°C. Methyl bromide is not expected to run
off fields to surface water because of application methods.
Ecological Characteristics:
Based on the registered patterns of use, no exposure to endangered
species is expected.
Efficacy Review Results: N/A
Tolerance Assessments:
Tolerances are established at §180.123 of 40 CFR for residues of
inorganic bromide (iBr) (calculated as Br) in or on a wide variety of
agricultural commodities which have been fumigated with methyl bromide
after harvest. Tolerances range from 5ppm — 24Oppm, with the majority
at 5Oppm or less.
Tolerances are established at §180.199 of 40 CFR for residues of
inorganic bromides (calculated as Br) in or on various raw agricultural
commodities grown in soil fumigated with combinations of chloropicrin
and methyl bromide.
Tolerances are established at §193.225 of 21 CFR for residues of
inorganic bromides (calculated as Br) in or on milled fractions derived
from cereal grains which have been fumigated with methyl bromide from
all fumigation sources, including fumigation of grain—mill machinery,
not to exceed 125 parts per million.
Tolerances are established at §193.230 of 21 CFR for residues of
inorganic bromides (calculated as Br) in or on corn grits and cracked
rice used in the production of fermented malt beverages which have
been fumigated with methyl bromide. not to exceed 125 parts per million.
Residues of inorganic bromides (calculated as Br) in the fermented
malt beverage cannot exceed 25 parts per million.
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Tolerances are established at *193.250 of 2! CFR for residues of
inorganic bromide (calculated as Br) in or on the following processed
food which have been fumigated with methyl bromide:
400 parts per million in or on dried eggs and processed herbs and
spices.
325 parts per million in or on parmesan cheese and roquefort cheese.
250 parts per million in or on concentrated tomato products and dried
figs.
125 parts per million in or on processed foods other than those listed
above.
Tolerances are established at *561.260 of 21 CFR for residues of
inorganic bromide (calculated as Br) in or on the following processed
feed which have been fumigated with methyl bromide:
400 parts per million for residues in or on dog food.
125 parts per million for residues in or on milled fractions for
animal feed from barley, corn, grain sorghum (milo), oats, rice, rye
and wheat.
Data gaps exist for storage stability and the metabolism of methyl
bromide in plant commodities fumigated postharvest. The requirements
for animal metabolism data and livestock feeding studies are reserved
pending the results of plant metabolism, storage stability, and plant
residue data.
Pending submission of the requested plant metabolism data (and the
conditionally required animal metabolism data), inorganic bromides
and methyl bromide p se (MeBr 2 L se) will tentatively be
considered the only residues of concern resulting from both preplant
soil and stored commodity fumigations. If the requested metabolism
data and residue data on feed items so indicate, livestock metabolism
and/or feeding studies involving iBr and MeBr se may be required.
Upon receipt of these studies, the Agency will determine the necessity
and magnitude of tolerances in animal products for iBr, MeBr se,
and perhaps other metabolites of concern if found in metabolism studies.
None of the iBr tolerances in or on raw agricultural commodities
(RACs) or processed products are supported due to the inadequacy of
available data (40 CFR 180.123 and 180.199; 21 CFR 193.225, 193.250,
and 561.260). In addition, data are required for each registered RAC
and processed product depicting the residues of MeBr se resulting
from stored commodity fumigation (and possibly preplant soil fumigation).
If both preplant and stored commodity fumigations are registered uses
on a given commodity, then data are required depicting both iBr and
MeBr se residues resulting from the combination of the two types of
treatment.
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No crop group tolerances, as specified under 40 CFR 180.34(f), may be
established at this time.
The ThRC for inorganic bromides is 25 mg/day based on a 1.5 kg diet.
The ADI is 1.1 mg/kg/day (set by FDA); currently the TMRC accounts
for 37.35 percent of the ADI.
4. Summary of Regulatory Position and Rationale
Methyl bromide is not being placed in the Special Review process at
this time. Although the Agency is concerned about the acute toxicity
risks associated with the use of methyl bromide, it believes that the
precautionary labeling measures required by this standard, monitoring
to establish safe levels for reentry to enclosed spaces and the
addition of chioropicrin to formulations as a warning agent will
significantly reduce these risks.
The Agency is requiring that chloropicrin at a concentration between
0.25% and 2.0% be present as a warning agent in all formulations,
except those used for commodity fumigation. Since methyl bromide is
odorless, the use of chioropicrin with its ability to cause painful
iritation to the eyes, producing tearing and its disagreeable pungent
odor at low concentrations will warn workers of methyl bromide exposure
and will promote its safe use.
Methyl bromide products that are restricted according to 40 CFR 162.31
will continue to be restricted. Additionally, the Agency will propose to
amend 40 CFR 162.31 to require restricted—use classification of all other
product containers of methyl bromide. The restricted—use classification
is necessary to protect users from the acute toxic effects of methyl
bromide.
Because of the limitations of space on labels and the complexity of the
precautions necessary to safely use methyl bromide, the Agency will require
the development of application manuals by the manufacturers.
The Agency will continue to require that enclosed spaces fumigated with
methyl bromide be aerated until the level of methyl bromide is below 5
ppm. This level was established under the Label Improvement Program for
Fumigants, PR Notice 85—6, August 30, 1985, because the Agency was concerned
about the possible inhalation exposure of workers.
Based on all available data, the Agency has determined that during soil
fumigation the concentration of MeBr in the working area will not generally
exceed 5 ppm as a time weighted average and will not require approved
respiratory equipment to be worn. Such equipment is required to be
available on the premises in case of a spill or leak.
The Agency will not impose a special label advisory statement for endangered
species at this time because there is no expected exposure ba8ed on the
registered patterns of use.
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The Agency will require the submission of supporting data to support the
current tolerances for mangoes, papayas, pomegranates, and cumin seed.
There are no registered uses for these commodities, but the tolerances
may be required for importation purposes. if the data are not developed,
these tolerances may be revoked.
Due to the inadequency of available data, the Agency is requiring
the submission of residue chemistry data to support all current inorganic
bromide tolerances and to establish tolerances for methyl bromide 2
se.
Since none of the current methyl bromide tolerances are supported by
data, no crop group tolerances, as specified under 40 CFR 180.34(f)
may be established at this time. When data are received, crop grouping
will be considered.
Since tolerances for methyl bromide 2 se are now being required, the
Agency will propose to delete 40 CFR 180.3(c), the section which
currently exempts the organic molecule from tolerances.
As soon as the required inorganic bromide data have been submitted, the
Agency will consider deleting all existing paragraphs in the 21 and
40 CFR concerning inorganic bromide tolerances and replacing them
with a single paragraph for raw agricultural commodities (40 CYR 180)
and processed products (21 CFR 193 and 561).
Because of the residue and toxicology data gaps for methyl bromide,
the Agency will not consider significant new food uses until the data
are submitted.
While data gaps are being filled, currently registered manufacturing—use
and end—use product containing methyl bromide may be sold, distributed,
formulated, and used, subject to the requirements of the methyl bromide
registration standard. The Agency does not normally cancel or withhold
registration for previously registered use patterns simply because
data are missing or inadequate. Data required under that Standard
will be reviewed and evaluated, after which the Agency will determine
if additional regulatory changes are necessary.
Unique Warning Statements: Restricted—Use for retail sale to and use
only by Certified Applicators or persons under their direct supervision,
and only for those uses covered by the Certified Applicator’s certification.
Applicators must wear loose cotton long sleeve shirts and pants, shoes
and socks that are cleaned after each wearing. Gloves and boots should
not be worn, as methyl bromide is heavier than air and may be trapped
inside and cause skin injury. Labeling for end—use products intended
for structural, transportation, space, or commodity fumigation require
the use of a self—contained breathing apparatus (SCBA) or combination
air—supplied/SCBA respirator If the concentration in the working area
exceeds 5 ppm (20 ing/m3). Labeling for end use products intended for
outdoor (soil fumigation) uses require approved respiratory equipment
to be available in case of emergency situations but do not require
SCBA under normal conditions of use.
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5. Suary of Major Data Gaps
Residue Chemistry:
Plant Metabolism: Due August 1987
Plant Residue Analytical Methods: Due February 1988
Storage Stability Data: Due February 1988
Magnitude of the Residue Studies: Due August 1989
Environmental Fate:
Photodegradation in Water: Due May 1987
Aerobic Soil: Currently under review
Anaerobic Soil: Currently under review
Leaching and Adsorption/Desorption: Currently under review
Field Dissipation Studies—Soil: Currently under review
Toxicology:
90—Day Inhalation—Rat: Due November 1987
90—Day Inhalation—Rabbit: Due November 1987
Chronic Toxicity—Rat (Gavage): Due October 1990
Chronic Toxicity—Dog (Gavage): Due October 1990
Oncogenicity—Rat (Inhalation): Due January 1987
Oncogenicity—Mouse (Inhalation): Due January 1987
Oncogenicity—Rat (Gavage): Due October 1990
Oncogenicity—Rat (Gavage): Due October 1990
Teratogenicity—Rabbit: Due November 1987
Reproduction—Rat (Inhalation): Currently under review
Reproduction—Rat (Gavage): Due November 1989
Mutagenicity: Due August 1987
Reentry:
Soil Dissipation: Due November 1988
Inhalation Exposure: Currently under review
6. Contact Person at EPA
Walter C. Francis, PM Team (32)
Registration Division (TS—767C)
Disinfectants Branch
401 M Street, S.W.
Washington, D.C. 20460
Telephone: (703) 557—3964
DISCLAIMER: The information present in this Chemical Information
Fact Sheet is for informational purposes only and may not be used
to fulfill data requirements for pesticide registration and
reregistration.
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