Methyl Bromide - Chemical Fact Sheet 8/86
CHEMICAL FACT SHEET FOR:
FACT SHEET NUMBER: 98
DATE ISSUED: AUGUST 22, 1986
1. DESCRIPTION OF CHEMICAL
Generic Name: Bromomethane
Common Name: Methyl Bromide
Trade Names: Brom-O-Gas-TM; Celfume-TM; Dowfume-TM; Embafume-TM;
Kayafume-TM; Meth-O GasTM; Terr-O-Gas 100TM
EPA Shaughenessy Code: 053201
Chemical Abstracts Service (CAS) Number: 74-83-9
Year of Initial Registration: 1961
Pesticide Type: Acaricide; Fungicide; Herbicide; Insecticide;
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.
- Application Rates: For stored product pests infesting raw
agricultural commodities, dosage rates are between 2-6 lbs/1000 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
3. SCIENCE FINDINGS
- Physical State: Gaseous, liquid under pressure
- Odor: Odorless
- Boiling Point: 4 degrees C.
- Melting Point: -94 degrees 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.
- Acute Oral Toxicity: Toxicity Category II; LD50 in the rat is 214
- Acute Inhalation Toxicity: Toxicity Category I based on human
experience and use history; LD50 is 2700 ppm for a 30 minute
exposure in the rat; in humans, 1,583 ppm (6.2 mg/1) was lethal to
adults exposed for 10-20 hours while 7,890 ppm (30.9 mg/1) 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
- 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
- Hydrolysis data indicate that methyl bromide breaks down at a rate
of 1.4 mg/liter water/day at 25 degrees C. Methyl bromide is not
expected to run off fields to surface water because of application
- Based on the registered patterns of use, no exposure to endangered
species is expected.
Efficacy Review Results
- 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 - 240ppm, with
the majority at 50ppm 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 Br 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
- Tolerances are established at 193.250 of 21 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
- 325 parts per million in or on Parmesan cheese and Roquefort
- 250 parts per million in or on concentrated tomato products and
- 125 parts per million in or on processed foods other than those
- 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 per se (MeBr per 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 per 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 per 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 per 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 per se residues resulting from the
combination of the two types of treatment.
Problems Known to Have Occurred with Use of the Chemical
- 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
Summary Science Statement
- 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.
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 chloropicrin 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 chloropicrin with its ability to cause painful
irritation 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
- 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
- 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
based on the registered patterns of use.
- 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 inadequacy 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 per
- 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 per se are now being required, the
Agency will propose to delete 40 CFR 180.(((3c))), 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 CFR 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
- 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 mg/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.
5. SUMMARY 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
- 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-Mouse (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
- Soil Dissipation: Due November 1988
- Inhalation Exposure: Currently under review
6. CONTACT PERSON AT EPA
Walter C. Francis
Product Manager Number 32
Registration Division (TS-767C)
401 M Street, S.W.
Washington, DC 20460
DISCLAIMER: THE INFORMATION PRESENTED IN THIS CHEMICAL INFORMATION FACT
SHEET IS FOR INFORMATIONAL PURPOSES ONLY AND NOT TO BE USED TO FULFILL
DATA REQUIREMENTS FOR PESTICIDE REGISTRATION AND REREGISTRATION.