It is now a well established
fact that some widely used man-made chemicals are destroying
the stratospheric ozone layer which shields the Earth
from dangerous ultraviolet radiation from the Sun. Depletion
of this vital shield will have grave consequences for
human health, for our food production systems, and ultimately
for the entire earth ecosystem.
Fortunately, a strong international consensus
on protection of the ozone layer has developed and has
been given form in the Montreal Protocol on Substances
that Deplete the Ozone Layer. The Montreal Protocol, which
came into force in January 1989, provides a legal basis
for the worldwide effort to safeguard the ozone layer.
Under the terms of the Protocol, the signatory countries
(called Parties for the Purposes of the Protocol) agree
to phase out production and use of identified ozone-depleting
substances (ODS) according to time scales fixed by the
Parties. Methyl Bromide has been identified as one of
the chemicals depleting the ozone layer. First brought
under the Montreal Protocol by the Copenhagen Amendment
of 1992, its phase out is now considered a very important
Although methyl bromide is hardly a household word, it
is widely used in some countries to control pests which
could reduce crop yields, and infest our food, buildings,
and transport vehicles. Around 97 percent of all of the
methyl bromide produced and sold is used as a fumigant
for pest control. It is this use which is covered by this
Since methyl bromide is used to control
a wide range of pests, there is no single substance which
can replace it in every case. This is not to say that
alternatives do not exist. In fact, UNEP’s Methyl
Bromide Technical Options Committee has identified alternatives
for the vast majority of uses of methyl bromide, often
combining several treatments to control the same range
of pests as methyl bromide. Furthermore, it is worth bearing
in mind that virtually every type of crop is being produced
commercially somewhere in the world without methyl bromide.
This booklet explains the general background
to ozone depletion, the Montreal Protocol , examines the
health effects and uses of methyl bromide, and describes
alternatives currently in use or under development.
OZONE LAYER DEPLETION
The earth’s stratosphere contains
a layer of ozone molecules, which is commonly referred
to as “the ozone layer”. These molecules are
made up of three oxygen atoms (O3) and are naturally broken
down into oxygen (O2 and O) by ultraviolet radiation (UV-B)
from the sun and by certain chemicals such as bromine
from methyl bromide. Ozone molecules are continually re-forming,
a process that once kept natural levels of stratospheric
ozone fairly constant. Most of the UV-B that reaches the
stratosphere is absorbed in this process by ozone molecules.
In recent years, however, scientists realized that ozone-depleting
chemicals such as methyl bromide (MB) and chlorofluorocarbons
(CFCs) have led to significant reduction in the total
amount of ozone in the stratosphere.
Methyl bromide and CFC molecules exert their
destructive effect upon ozone by breaking down into reactive
chlorine and bromine when they reach the stratosphere.
These molecules then react with ozone, breaking it down
into oxygen. CFCs (which are slowly degraded to produce
chlorine atoms) have a half-life of 40 to 70 years in
the stratosphere (Makhijani and Gurney, 1992), while methyl
bromide (which releases bromine atoms) lasts less than
2 years. In that time, however, one bromine atom can break
down about 50 times as much ozone as chlorine (UNEP et
al.,1994). The short halflife of methyl bromide in the
stratosphere means that benefits from methyl bromide control
would be rapidly attained-over a few years- in contrast
to CFCs where effects are apparent only over decades.
Methyl Bromide is a broad spectrum pesticide
used in the control of pest insects, nematodes, weeds,
pathogens, and rodents. A very high proportion of methyl
bromide is used for fumigation. This process is thus considered
the most significant source of man-made emissions to the
atmosphere. Depending on the process and methods employed,
emission can vary from 30 to 95% of the methyl bromide
used. In 1994, the UNEP Methyl Bromide Technical Options
Committee (MBTOC) estimated that the average emission
for all types of fumigation processes using methyl bromide
was 64% worldwide. Emissions occur mainly at three stages
in the fumigation process:
• During treatment, due to leaks.
• Immediately after treatment, when fumigation spaces
are vented or plastic sheeting is removed from soils.
• Following treatment, when methyl bromide absorbed
by soil particles or by commodities and structures is
DIRECT EFFECTS ON HUMAN HEALTH
Aside from its effect on the ozone layer,
methyl bromide also has adverse effects on human health.
If inhaled or absorbed through the skin, high concentrations
of methyl bromide can cause a variety of acute problems,
including chest pain, difficulty in breathing and congestion
of the lungs. After a short amount of time, neurological
symptoms such as headaches, nausea, shortness of breath,
muscle tremors and visual disturbances occur. Exposure
to high levels of the fumigant can lead to seizures or
even death hours or days after the exposure (WHO,1991).
Toxicology studies indicate that when pregnant animals
are exposed to methyl bromide, their unborn fetuses can
suffer birth defects (California Department of Pesticide
Regulation, 1994). The United States Environmental Protection
Agency (EPA) classifies methyl bromide as a Category 1
acute toxin, a label reserved for the most dangerous category
of substances (U.S. EPA, 1986).
The World Health Organization (WHO) reports
that human exposure to methyl bromide (through inhalation
and skin contact) is primarily occupational, particularly
during soil or bulk fumigation, although the general population
in the vicinity of fumigated fields or buildings may also
be exposed (WHO, 1994b). After absorption, methyl bromide
or its metabolites are rapidly distributed to many tissues
including the lungs, adrenal glands, kidneys, liver and
the brain (WHO,1994b). Fatal poisonings results from exposure
to relatively high concentrations of methyl bromide vapor.
EFFECTS OF OZONE DEPLETION ON HUMAN
HEALTH AND THE ENVIRONMENT
UV-B radiation affects human health in a
variety of ways. It weakens the immune system, which defends
the human body against disease, and has been shown to
cause skin cancer and damage eyesight (Environmental Effects
Panel, 1994). Scientists estimate that a 1% increase in
ozone depletion may be associated with a 0.6% to 0.8%
increase in eye cataracts, a leading cause of blindness
(Environmental Effects Panel, 1994). Ozone depletion is
also directly linked to skin cancer. UNEP estimates that
a sustained 1% decrease in stratospheric ozone will result
in an increase in non-melanoma skin cancer incidence of
approximately 2% (Environmental Effects Panel, 1994).
Probably the most serious consequence of
excessive UV-B exposure is direct suppression of the human
immune system, which reduces the body’s ability
to combat infection. Immuno-suppression can in turn increase
the number and severity of bacterial and viral diseases,
as well as decrease the immune response to skin cancer
and infectious diseases. Excessive UV-B exposure may also
activate the HIV virus, hastening the onset of full-blown
The effect of increased levels of UV_B
upon plants and the earth’s ecosystems may turn
out to be even more significant than the effect on humans
and other animals. The earth’s food chains rely
on the conversion of sunlight into food by terrestrial
plants and microscopic marine phytoplankton. Studies have
shown a direct reduction in phytoplankton production due
to increases in UV-B radiation; one estimate indicates
that phytoplankton populations beneath the Antarctic ozone
“hole” have declined as much as 12% in recent
years (Environmental Effects Panel, 1994). Phytoplankton
serve as the base of the marine food chain-at the top
of these food chains are people, who will ultimately suffer
from UV-B’s adverse effects on terrestrial and marine
Scientists are just beginning to understand the negative
effects of UV-B on tree growth, aquatic ecosystems and
possible adverse impacts on world food production (UNEP,1992).
For example, UNEP’s Report on the Environmental
Effects of Ozone Depletion notes that solar UV-B radiation
has been found to damage the early developmental stages
of fish, shrimp, crab amphibians and other animals; the
most severe effects are decreased reproductive capacity
and impaired larval development (Environmental Effects
Panel, 1994). Researchers do not know all the effects
of increased levels of UV-B, but current studies indicate
that the impacts on human health and natural ecosystems
are likely to be serious.
AND METHYL BROMIDE
THE MONTREAL PROTOCOL
The Montreal Protocol is the spearhead
of the international effort to protect the ozone layer.
The Protocol came into force in January 1989. By 1998
it had been ratified by more than 160 countries. Ratification
means that the signatory countries agree to be legally
bound by the Protocol’s requirements.
Protocol Parties (governments) discuss and
agree on commitments to limit production and consumption
of ozone-depleting substances, known as “controlled
substances” for the purposes of the Protocol. Originally,
control measures were introduced on eight substances five
CFCs and three halons. However, as scientific investigations
progressed, further ozone-depleting substances were identified.
It became clear that if protection of the ozone layer
was to be effective, substances depleting it would have
to be phased out altogether. Methyl bromide was officially
listed as a controlled substance under the Copenhagen
Amendment to the Montreal Protocol in 1992. Since then
the necessity for faster action on phase out has been
The Parties to the Montreal Protocol recognize
that developing countries should be given additional time
to phase out methyl bromide, given the special circumstances
they face. A grace period of ten years for implementation
of the measures required by the Protocol was therefore
generally agreed for developing (Article 5) countries.
Article 5 countries are developing countries which consume
less than 0.3 kg per capita per annum of controlled substances.
They are so called because their status is defined in
Article 5 of the Montreal Protocol.
After the latest amendments and adjustments,
introduced into the Protocol under the Montreal Amendment
of 1997, the phase out schedule for methyl bromide is
as shown on the next page :
OUT OF METHYL BROMIDE
UNDER THE MONTREAL PROTOCOL – 1997
• 25% reduction by 1999
• Freeze by 2002 at average 1995-1998 base
• 50% reduction by 2001
• Review of reduction schedule in 2003
• 70% reduction by 2003
• 20% reduction by 2005
• Phaseout by 2005 except for critical
• Phaseout by 2015 except for critical
Note : Pre-shipment and quarantine uses
(about 22% of global methyl bromide use) are exempt from
Under the Protocol quarantine and pre-shipment
uses of methyl bromide, which comprise an estimated 22%
of global methyl bromide use, are exempt from control.
The aim of quarantine regulations is to avoid inadvertently
transporting pests, along with commodities, to places
where they are not already present or where they are already
officially being controlled. Pre-shipment treatment is
applied directly prior to exporting of commodities, to
meet official pest-control regulations applying in either
the importing or the exporting country. Banning of approved
quarantine treatments before alternatives are commercially
available could severely curtail international trade,
and therefore such cases are granted exemption under the
METHYL BROMIDE CONSUMPTION
About 71,500 tonnes of methyl bromide are
used annually worldwide, with approximately 75 % used
in industrialized countries and 25 % in developing nations.
Patterns of use vary from country to country. However,
roughly 70% of MB use in the developing world is for soil
fumigation, 10% for grain storage and about 20% for quarantine
/ pre-shipment uses. (MBTOC, 1998)
Although the developing world uses much
less MB than industrialized nations, MB consumption in
developing countries has risen rapidly in recent years.
According to a survey by UNDP of 25 developing countries,
overall use almost doubled from 1990-1994 (from 3,766
to 7,086 tonnes). (TEAP,1997) This rapid increase in developing
nation use led the Montreal Protocol’s Technology
and Economic Assessment Panel (TEAP) to conclude that
“At these rates of increase, the (developing) countries
have the potential to completely overwhelm progress made
elsewhere in the world in a relatively short period of
METHYL BROMIDE USES
Methyl bromide is used in the following
• Soil fumigation – to kill organisms in soil
prior to planting certain horticultural crops, such as
strawberries, tobacco, and flowers. The chemical is injected
into the soil, which is usually covered by a plastic sheet
to contain the pesticide until the organisms are killed
or the gas has evaporated (typically within three or four
days). Fumigating perishable goods for quarantine –
to kill organisms on or in food and other exported products
either at the point of export or import. Target pests
include fungi, moths, fruit flies, scale insects, aphids
and snails which can infest cut flowers, grapes, strawberries,
asparagus and other fresh produce. Treatments are often
required by quarantine regulations of importing countries.
• Fumigating durable goods such as
timber, wood products, dried spices and large lots of
grains like maize and wheat to eliminate pests and infestation
such as moths, termites, fungi and rodents during storage
Structural fumigation – to kill organisms,
such as termites, that can damage buildings and other
structures and to disinfest aircraft, ships and transportation
containers from insects, rodents, and other pests.
No single substance has been found that can substitute
for the wide range of methyl bromide uses. However, alternatives
have been identified for more than 90% of all methyl bromide
uses. While some of these are chemical pesticides, many
alternatives are of the ‘not-in-kind’ variety
and consist of different approaches to the specific pest
problem, including avoiding the circumstances which made
methyl bromide use necessary in the first place.
Alternatives may improve or reduce production
and profitability but there are often substantial advantages
to discontinuing methyl bromide use. Methyl bromide has
already been phased out for fumigation in Denmark and
the Netherlands. It is encouraging that some of the alternative
treatments used there have increased crop yields and profitability.
In addition, some developing countries, including Colombia
and Indonesia, have already found effective alternatives
to replace methyl bromide.
Existing and potential alternatives for
the different uses of methyl bromide are listed on the
A. Non-Chemical Alternatives
• SOIL-LESS CULTURE AND ARTIFICIAL PLANT GROWTH
SUBSTRATES (soil substitutes) such as rock wool in greenhouses
and open fields with suitable economic and climatic conditions.
• NATURAL SUBSTITUTES such as small stones and waste
• CROP ROTATION is the planting of successive crops,
which are non-host, less-suitable host or trap crops for
target pathogens. This technique is in widespread use
and can be very effective in managing soil-borne pests.
Limited by availability of land, persistent pests, appropriate
rotational crops, equipment, expertise and socio-economic
• LEAVING LAND FALLOW to reduce soil pest populations
by denying them hosts and/or substrates for growth. Limited
in areas with high land values, shortages of agricultural
lands and when pests can survive prolonged fallow periods.
• PLANTING CROPS which can be produced and marketed
at a time when pest density and/or activity are low.
• DEEP PLOUGHING to reduce pathogen inoculum through
burial of reproductive structures and stimulation of microbial
activity by decomposition of crop debris FLOODING AND
WATER MANAGEMENT (where suitable) to produce metabolites
toxic to soil-borne pests.
• COVER CROPS, non-commercial crops which are planted
then turned back into the soil as green or dry residue
to stimulate the activity of micro-organisms antagonistic
to soil-borne pests. Cover crops must not compete with
the commercial crop.
• LIVING MULCHES, cover crops grown with the main
crop in order to suppress weeds and reduce insect pests
without reducing yields.
• BIOFUMIGATION which involves ploughing in specific
crops, notably Brassicas, which give off natural fumigants
that kill or control pests (a technique that can be enhanced
in combination with solarization).
• FERTILIZATION AND PLANT NUTRITION which, if carefully
managed, can reduce the development of pathogens and diseases.
RESISTANT CULTIVARS (VARIETIES) developed through the
use of plant breeding are resistant or tolerant to soil-borne
pathogens/pests. Resistant varieties are available for
most crop species and can be integrated within crop rotation
systems to enhance suppression of pathogens. However,
it is difficult to develop cultivars resistant to multiple
pathogens. Resistant cultivars are an important component
of an Integrated Pest Management system (IPM). IPM is
a system that uses a rational combination of pestcontrol
practices and techniques to achieve a satisfactory pest
• GRAFTING is a method that involves using resistant
rootstocks for susceptible annual or perennial crops to
control soil-borne pathogens. It has proven effective
in controlling soil-borne pathogens for such crops as
cucurbits, tomatoes, citrus, grapes and fruit trees.
Many organisms are antagonistic to plant pathogens. They
can be successfully used to control soil-borne pests.
Their spectrum of activity and host specificity is very
narrow so they must be used as a part of an IPM system.
The number of commercialized products is limited but increasing.
Adding organic matter such as composts, sewage, and by-products
from agriculture, forests, and the food industry can help
manage soil-borne pests and diseases and improve physical
soil properties. However, the efficacy of these additions
depends on their chemical and physical properties, and
the use of materials that are locally available.
SOIL SOLARIZATION, which involves covering moist soil
with thin clear plastic sheeting and letting the sun heat
the soil to a temperature lethal to some pests. Solarization
is used in more than 40 countries. It is most effectively
used on heavier soils and/or semi-arid regions where there
is intense sunshine and minimal rainfall. Solarization
has shown to control a broad spectrum of pests, but there
are some important pests which it does not consistently
control. Therefore solarization should be used as part
of an IPM system to be most effective.
• STEAM elevates soil temperatures to 70-80°C,
which pasteurizes the soil and reduces soil-borne pests
as efficiently as methyl bromide fumigation. It is used
extensively for bulk soil or small-scale field treatments
with greenhouses. Its use is limited by energy costs,
capital investments and some types of soil. Technological
improvements are needed to expand the use of steam for
large-scale open-field production systems.
• HOT WATER TREATMENT can be used to control weeds
• WAVELENGTH-SELECTIVE PLASTIC MULCHES allow heat-generating
radiation to heat the soil but exclude photosynthetic
wavelengths, thus preventing weed growth.
B. Chemical Alternatives
A number of chemicals can be considered
as alternatives to methyl bromide. Some are readily available
while others are undergoing research and evaluation. No
single chemical alternative alone has the ability to control
the broad range of pests controlled by methyl bromide.
Therefore combinations of chemicals and/or other pest
control techniques are necessary. Their toxicity and safety
are of particular concern since, in the future, health
and environmental considerations are likely to limit the
use of any pesticide
• CHLOROPICRIN adequately controls a number of pests
including most soil-borne fungi, root destroying insects
and fruit harming organisms. However, it does not control
nematodes or weeds. It can also be used with other pesticides
(1,3-Dichloropropene) or other pest control methods (solarization)
to achieve broad spectrum control. Regulatory restrictions
could limit its future use.
• 1,3-DICHLOROPROPENE (1,3-D) has been shown to
effectively control nematodes and insects. It also has
the ability to suppress some weeds and pathogenic fungi.
Research is being conducted to develop combination treatments
with other pesticides to provide adequate control for
a broad spectrum of pests. I,3-D poses environmental and
health problems, and has contaminated air and groundwater.
METAM SODIUM provides effective control of some weeds
and soil-borne pathogens (primarily fungi), and a limited
number of parasitic nematode species. Recent studies have
shown that it does not provide consistent pest control
due to non-uniform distribution in the soil. Research
is being conducted to improve chemical dispersion systems
and also to use metam sodium in combination with other
pest control methods (solarization).
• DAZOMET has shown to control weeds, nematodes,
and fungi. It does not always consistently control pests
due to non-uniform distribution in soil.
• MIXTURES OF SOIL FUMIGANTS may be as effective
as methyl bromide in terms of spectrum of pest control,
thus representing the most promising short-term alternative.
However, pre-formulated mixtures need to be tested and
Approximately the same level of pest control
as that of methyl bromide can be achieved by combining
several non-fumigant chemicals that provide control of
specific pests (such as herbicides, fungicides, nematicides
and insecticides) or by combining them with fumigants
or non-chemical techniques.
However, many soil pests can develop resistance to these
combinations and soil microflora can sometimes decompose
them. Furthermore, their use is likely to be limited for
health and environmental reasons.
Physical control methods
• COLD TREATMENTS are generally used to prevent
multiplication or reinvasion of pests, but they also offer
an alternative to fumigation with methyl bromide when
a mild non-chemical disinfestation is needed.
• HEAT TREATMENTS can control pests as fast as methyl
bromide and other fast-acting fumigants. They involve
heating commodities to temperatures of 50-70°C and
cooling them rapidly where necessary to avoid damage.
Capital costs are high.
• IRRADIATION of commodities with gamma rays, X-rays
or accelerated electrons is an effective method of pest
control, already used in some situations. Further development
is hindered by the lack of international agreements regarding
trade and quarantine requirements of irradiated products.
Consumer acceptance of irradiated food products is another
impediment, as is cost.
• SANITATION AND PREVENTATIVE PRACTICES (physical
removal) includes practices such as cleaning, removal
of food residues and stock rotation-measures that are
part of the normal management of stored durables. The
aim of sanitation is to prevent pests from multiplying
and to reduce the need for pest control by removing pests
or keeping them away from the commodity.
Fumigants and other gases
• PHOSPHINE is a very toxic fumigant but it is used
at low concentrations. It penetrates well, produces few
residues and is effective for disinfestation of most durables.
Yet phosphine requires much longer exposure than methyl
bromide; it is not very effective at low temperatures;
and some pests can develop resistance to it. Pest resistance
can be overcome by increasing the period of treatment
under well-sealed conditions.
• ETHYL FORMATE’s use is restricted to dried
fruit and processed cereals, and only in some countries.
CARBON BISULPHIDE was previously widely used but has been
discontinued in most parts of the world because of its
potential fire hazard.
• CARBONYL SULPHIDE is an insecticide that is not
yet registered as a fumigant
• OZONE is showing some potential as a fumigant
but further research is required.
• METHYL ISOTHIOCYANATE is being studied as a grain
fumigant and protectant.
• SULFURYL FLUORIDE is mainly used against termites.
It is not registered for use on foodstuffs.
• ETHYLENE OXIDE, once extensively used on food
commodities, was withdrawn in many countries because it
produces carcinogenic residues.
• CONTROLLED AND MODIFIED ATMOSPHERE TREATMENTS,
based on carbon dioxide and nitrogen, can lead to effective
pest control. Their limitations are long exposure times
especially at low temperatures (for example 4-8 weeks
at 15°C) and the need for a very high degree of sealing.
• ORGANOPHOSPHORUS COMPOUNDS are widely used as
grain protectants. The speed at which such chemicals degrade
is highly dependent on temperature and moisture.
• SYNTHETIC PYRETHROIDS are insecticides which are
quite stable on grain and can be effective for up to two
• BOTANICALS are derived from plants. Many are used
in developing countries but there is little incentive
for companies in developed countries to register them.
• INSECT GROWTH REGULATORS (IGRs) are used to protect
agricultural commodities. They act by interfering with
the life cycle of pests and are not normally able to control
adult pests. Their persistence on foodstuffs may limit
some of their uses.
• INERT DUSTS can provide effective, inexpensive,
non-toxic and continued pest control in grain. Diatomateous
earth is one type of inert dust that has been in widespread
use in grain storage for several years as part of an IPM
system. The main disadvantages of inert dusts are visible
residues and dust problems in the work area.
• BIOLOGICAL CONTROL WITH INSECTS OR PARASITES can
be an effective method of pest control. However, regulations
need to be revised if beneficial insects are not to be
considered as contaminants.
• INSECT PATHOGENS such as bacteria, viruses, protozoa,
nematodes and fungi can also be used to help control pests.
Some are registered as stored product protectants, but
many are still undergoing field tests.
• PHEROMONES are chemicals that are released by
insects in order to control the behavior of other insects
of the same species. It may be possible to control pests
via synthetic pheromones either by stimulating or inhibiting
specific behavior patterns, especially mating.
• THE SYSTEMS APPROACH, which consists of reducing
the pest population at each stage of commodity production
and packing. It requires considerable documentation on
CULTURAL PRACTICES such as planting pest-resistant commodities,
harvesting when the pest is not active, and adding biological
or microbial agents to control pests. The presence of
agents may not comply with quarantine requirements.
• GROWING IN PEST-FREE ZONES AND PERIODS
is accepted by some countries as sufficient treatment.
Certification of pest-free zones requires justification
through monitoring, reporting, and enforcement. The system
is operated in the United States, Japan and New Zealand.
• COLD TREATMENT (between -1°C and +2°C)
is usually applied to fruit infested with tropical pests.
Detailed documentation is required by importing authorities.
• HEAT TREATMENT (40-50°C) is used to control
pests found in or on tropical and sub-tropical commodities.
It is achieved through moist or dry air and immersion
in hot water. It is unsuitable for the most perishable
commodities and requires considerable energy inputs.
• CONTROLLED ATMOSPHERE (CA) disinfestations involves
storing products in facilities where a lack of oxygen
kills the pests. Carbon dioxide and nitrogen are used
to replace the oxygen. Since this treatment requires several
weeks or even months, it is only suited to perishables
that store well, such as apples and pears. There are few
commercial examples of CA used to control pests for quarantine.
MODIFIED ATMOSPHERE disinfestations consists in wrapping
perishables in airtight film and thus killing any pests
present. Commercial applications do not yet exist and
the process is under development. This technique will
be suitable only for controlling pest on perishables such
as strawberries that can be stored for at least seven
• IRRADIATION is approved by some
countries on foodstuffs such as fresh fruit and vegetables.
However, further adoption of irradiation for disinfestations
requires consumer, industry, and regulatory acceptance.
• MICROWAVE PEST CONTROL is at an early stage of
development. It may allow convenient on-site quarantine
treatment for small shipments of commodities. However,
the effects of microwaves on commodity quality remain
to be determined.
• PHYSICAL REMOVAL of pests from the surface of
fruit can be achieved with water under high pressure,
by blowing air on the fruit or by sucking pests off with
vacuum systems. These techniques are in limited commercial
• COMBINATIONS OF SEVERAL PEST CONTROL TECHNIQUES
may compensate for the limitations of individual treatments.
The efficacy of combinations needs to be demonstrated
and extensively documented for approval.
• FUMIGATION is particularly useful for controlling
pests inside the commodity. Alternatives to methyl bromide
include sulphur dioxide, methyl and ethyl formate, and
aerosol sprays using natural plant products such as pyrethroids.
For safety reasons, the registration of new fumigants
is a long and costly process.
CHEMICAL DIPS are very dilute pesticide solutions into
which commodities are dipped after harvest. They are used
to control pests which are in or on the perishable commodity.
The use and disposal of the solution can pose health and
IV. STRUCTURES AND TRANSPORTATION
A. Alternatives for pests other than wood-destroying
• PHOSPHINE and its effects on pests are well known.
But its structural use is limited because it can corrode
metals such as copper and gold, damage electrical equipment
and is flammable.
• SULPFURYL FLUORIDE is an alternative but it cannot
be used in structures and transportation linked with food
because its toxicity has not been established.
• HYDROGEN CYANIDE is efficient against rodents,
but is rarely used because of its toxicity. Strict regulations
govern its transport.
Atmospheres that are poor in oxygen (less than 1 percent)
and rich in carbon dioxide (more than 60 percent) are
toxic to insects. As this technique leaves no residue
on food, it is used in mills and food plants that can
be sealed off for at least ten days. Extra equipment may
be needed to improve gas circulation.
Combinations reduce the amount of fumigant used, and consequently
the cost of the treatment. Possible combinations include
fumigant and carbon dioxide; fumigant and heat; fumigant
and carbon dioxide and heat; and fumigant and fumigant.
A combination of phosphine, carbon dioxide, and heat has
shown to be effective in full scale trials. These combinations
are less dangerous to humans and the environment than
a fumigant used on its own.
• SPACE SPRAYS disperse particles that kill insects.
Sprays are used as part of a more extensive treatment
because they kill only adult insects that are in contact
• SURFACE APPLICATION of liquid residual pesticides-
applying pesticides such as organophosphates, carbamates
and pyrethroids directly to surfaces where insects breed-
is an easy but lengthy technique which has little effect
• RESIDUAL DUSTS are used in dry and undisturbed
areas, and are effective for a long time.
• SANITATION (in effect, good housekeeping or keeping
things clean) is fundamental to pest control, and is complementary
to all treatments.
• CONSTRUCTION AND MAINTENANCE are most important.
Sound building structures can greatly reduce nesting.
Structure retrofittings, even though expensive, should
therefore be considered. Moreover, sound structures and
effective maintenance improve the efficiency of alternative
• INERT DUSTS-such as silica gel-are very effective
on crawling insects. They can be used in cavity walls
and in relatively dry atmospheres.
• HEATING above 52°C is widely used to kill
food plant pests. This method leaves no residue. N some
cases it is combined with phosphine and carbon dioxide
mixtures. However, some buildings cannot withstand high
temperatures or be evenly heated, and sensitive equipment
has to removed and treated separately. TRAPPING DEVICES
such as glue board have a limited effect and imply a thorough
knowledge of the pests targeted. They must be properly
placed and regularly checked.
B. Alternatives for wood-destroying
• SULPHURYL FLUORIDE is well known and used in several
countries. It destroys insects at all life stages but
can be expensive. It may be preferred to methyl bromide
for treatment of museums and libraries.
• PHOSPHINE has limited use because it needs a long
fumigation time and may be corrosive to electrical components.
Combinations reduce the amount of fumigant used as well
as the exposure and aeration times. They involve fumigant
and carbon dioxide; fumigant and heat; fumigant and carbon
dioxide and heat; and fumigant and fumigant.
• SURFACE APPLICATION/INJECTION of liquid residual
pesticides is used for local treatment of accessible areas.
• DUSTS are used for local treatment and are active
for a long time, but their application is time consuming.
WOOD-PRESERVATIVE TREATMENT is used preventively on construction
wood. Its efficiency varies, and some products are dangerous
for humans and the environment.
• CONSTRUCTION AND REMOVAL. Good building design
is essential to reduce pest proliferation. The wood in
infested buildings should be replaced with pre-treated
• HEAT (more than 46°C) kills dry-wood termites.
Studies have to be carried out to improve knowledge concerning
the effects of heat on structures.
• COLD TREATMENT (with liquid nitrogen) can be used
in isolated but accessible areas. However, this technique
can stain and damage wood.
• ELECTROCUTION is a spot treatment (against termites)
which merits study and evaluation.
• MICROWAVE HEATING can kill most insects but it
can also damage wood and is only potentially suitable
for localized treatment.
Ships, aircraft and other forms of transportation
Methyl bromide is the only treatment used in ships during
quarantine. Hydrogen Cyanide (HCN), phosphine, rodenticides
and traps could replace it. HCN and phosphine act rapidly
on rodents, but the latter is slow and expensive for insects,
which could limit its use in developing countries. As
far as aircraft are concerned, residuals and sprays seem
to be the best alternatives but they need to act as rapidly
as methyl bromide to be cost-effective. Phosphine and
nitrogen-based controlled atmosphere alternatives are
being considered for other vehicles.
GETTING READY FOR THE PHASE OUT
As this booklet and other publications have
shown, there are safe, effective alternatives to methyl
bromide which are not harmful to the ozone layer. Many
of these are now available and are now in use, in both
developed and developing countries. However, developing
countries often need financial and technical assistance
to identify and adopt the alternatives which are appropriate
to their local conditions. It is in the areas of adaptation,
development, farmer training and education that developing
countries will require bilateral and multilateral aid.
Financial and other assistance is required to provide
developing countries with access to appropriate alternatives
and to avoid the risk of disruption of their trade.
Moreover, the phase out of methyl bromide
could provide developing countries with opportunities
to modernize their pest-control approaches and to develop
new industries to meet regional and international demands
for methyl bromide alternatives. In addition, commercial
pressure to move away from methyl bromide is beginning
to emerge with some supermarkets and traders selecting
produce grown without it. A developing country, or indeed
any country, that persists in the use of methyl bromide
may lose export markets as a result of commercial pressures.
At their 1990 meeting in London, the Parties
to the Protocol created the Multilateral Fund to provide
financial and technical assistance to developing countries
in establishing and implementing projects and programmes
for phase out of ozone-depleting substances. An additional
point, of great importance, is that financial aid for
substances covered by a particular amendment to the Protocol
is only available from the Multilateral Fund to those
countries which have ratified that amendment. Therefore,
for countries to receive financial assistance to implement
methyl bromide alternatives, they must first ratify the
Four organizations have been designated
as Implementing Agencies for the Multilateral Fund :
• The United Nations Development Programme (UNDP)
assists Parties in investment project planning and preparation,
country programmes and institutional strengthening, and
runs training and demonstration projects.
• The United Nations Environment Programme (UNEP)
through the UNEP IE OzonAction Programme, collects data,
provides an information clearinghouse, assists low-volume
consuming countries in the preparation of country programmes
and institutional strengthening projects, and offers training
and networking assistance.
The UnitedNations Industrial Development Organization
(UNIDO) runs small-to-medium-scale investment projects
and country programmes, and offers technical assistance
and training for individual facilities.
• The World Bank develops and implements investment
projects and assists in the preparation of country programmes.
It must be noted that, recognizing the urgency
of the need to phase out methyl bromide, the 1997 Amendments
to the Montreal Protocol brought forward the date for
its elimination in developed countries to 2005. Thus,
developing countries may well need help if we are to be
able to adopt alternatives in time to be ready for possible
rejection of products treated with methyl bromide by supermarkets
and consumers in developed countries when methyl bromide
is no longer available in industrialized regions.
In the Philippines, the Pesticide Action
Network (PAN-PHIL) ,through PAN – North America,
is currently working with UNEP in helping users of methyl
bromide in the country prepare for its eventual phase
out. The Methyl Bromide Communications Programme of UNEP
is being implemented to help users reduce their reliance
on methyl bromide, and to help them in transition to other
pest control alternatives in time for the upcoming methyl
bromide use reductions. Part of this program involves
making an initial survey of methyl bromide use. The data
obtained will be used as a basis for Workshops to be conducted
by PAN-PHIL for the users. Among the topics would be the
uses, effects, and alternatives to methyl bromide. Survey
results will also be used to aid in future policy-making
concerning the use of methyl bromide in the Philippines.
It is hoped that the information presented
in this booklet has encouraged the reader to take steps
in considering the alternatives that may be used in their
particular situation, and to support PAN-PHIL in its efforts
to help prepare the country for the phase out.
The organizations and people listed below
will be able to provide help and guidance about activities
and projects to help phase out methyl bromide:
• UNEP IE OzonAction Programme (UNEP
39-43 Quai Andre Citroen
75739 Paris Cedex 15
Tel: +33 1 44 37 14 50
Fax: +33 1 44 37 14 74
E-mail : firstname.lastname@example.org
• United Nations Environment Programme
Mr. K. M. Sarma
PO Box 30552 Nairobi
Tel: +254 2 623 885
Fax: +254 2 623 913
• UNEP Regional Office for Asia and
UN Building, Radjamnern Avenue
10200 Bangkok, Thailand
Tel: +66 2 280 60 88
Fax: +66 2 280 38 29
• United Nations Development Programme
1 United Nations Plaza
New York, NY 10017
Tel: +1 212 906 5042
Fax: +1 212 906 6947
• World Bank
1818 H St., NW
Washington, DC 20433
Tel: +1 202 477 1234
Fax: +1 202 522 3256
• United Nations Industrial Development
PO Box 300
Tel: +43 1 211 31 3782
Fax: +43 1 230 7449
• Multilateral Fund of the Montreal
1800 McGill College Avenue
Montreal, Quebec H3A 3J6
Tel: +1 514 282 1122
Fax: +1 514 282 0068
• Pesticide Action Network Philippines
L2 B30 Salome Tan St., Phase 5
BF Homes Executive Village
Las Piñas City, Metro Manila
Telefax: +63 2 805 0585
Portions of this booklet were obtained from
the following :
Pesticide Action Network North America.
Factsheet for the Methyl Bromide Communications Programme.
Schonfield, et al.1995. Under African Skies.
Pesticide Action Network North America Regional Center.
U.S. Environmental Protection Agency Methyl
Bromide Home Page, http://www.epa.gov/spdpublc/mbr/mbrqa.html
United Nations Environment Programme. 1998. Methyl Bromide
getting ready for the phase out. UNEP. France.
United Nations Environment Programme. 1998.
Protecting the Ozone Layer Volume 6: Methyl Bromide. UNEP.
Cited References :
California Department of Pesticide Regulation.
1994. Methyl Bromide (a Document Prepared for the Developmental
and Reproductive Toxicant Identification Committee for
the Consideration of Methyl Bromide as a Developmental
Toxicant under Proposition 65).March 7.
Environmental Effects Panel 1994, Environmental
Effects of Ozone Depletion: 1994 Assessment, United Nations
Makhijani, Arjun and Gurney, Kevin. 1992.
Mending the Ozone Hole. Institute for Energy and Environmental
Research. Takoma Park. Maryland. United Nations Environment
Programme, World Meteorological Organization, National
Aeronautics and Space Administration and National Oceanographic
Administration. 1994. Scientific Assessment of Ozone Depletion
United Nations Environment Programme. 1991.
Synthesis Report of Ozone Scientific Assessment Panel.
United Nations Environment Programme. 1992.
Synthesis Report of the Methyl Bromide Interim Scientific
Assessment and Technology/Economic Assessment. Montreal
Protocol Assessment Supplement. June.
World Health Organization. 1991. International
Programme on Chemical Safety Environmental Health Criteria
for Methyl Bromide. Geneva.
World Health Organization. 1994a. Recommended
Classification of Pesticides by Hazard and Guidelines
to Classification. 1994-1995. Geneva.
World Health Organization. 1994b.Methyl
Bromide Health and Safety Guide. Geneva.