Methyl Bromide: Getting Ready for the Phaseout

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 step.

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 booklet.

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.


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 gradually released.


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.


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 AIDS (UNEP,1991).

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 ecosystems.

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.



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 recognized.

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 :


Developed Countries

Developing countries

• 25% reduction by 1999

• Freeze by 2002 at average 1995-1998 base level

• 50% reduction by 2001

• Review of reduction schedule in 2003

• 70% reduction by 2003

• 20% reduction by 2005

• Phaseout by 2005 except for critical use exemptions

• Phaseout by 2015 except for critical use exemptions

Note : Pre-shipment and quarantine uses (about 22% of global methyl bromide use) are exempt from these controls.

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 Protocol.


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 time.”(TEAP,1997)


Methyl bromide is used in the following processes :

• 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 and transport.

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 following:

A. Non-Chemical Alternatives

Cultural Practices
• 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 products.
• 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 factors.
• 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 control solution.
• 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.

Biological controls
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.

Soil amendments
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.

Physical methods
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 and pests.
• 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

Available chemicals
• 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 registered.

Other chemicals

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.

Contact insecticides
• 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 years.
• 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 methods
• 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.


Pre-harvest alternatives
• THE SYSTEMS APPROACH, which consists of reducing the pest population at each stage of commodity production and packing. It requires considerable documentation on pests.
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.

Post-harvest treatment
• 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 days.

• 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 use.
• 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.

Chemical alternatives
• 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 environmental problems.

A. Alternatives for pests other than wood-destroying insects

• 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.

Controlled atmospheres
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.

Non-fumigant pesticides
• 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 with them.
• 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 on foodstuffs.
• RESIDUAL DUSTS are used in dry and undisturbed areas, and are effective for a long time.

Non-chemical treatment
• 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 treatments.
• 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 insects

• 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.

Non-fumigant pesticides
• 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.

Non-chemical methods
• CONSTRUCTION AND REMOVAL. Good building design is essential to reduce pest proliferation. The wood in infested buildings should be replaced with pre-treated wood.
• 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.


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 Copenhagen Amendment.

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 IE)
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 :

• United Nations Environment Programme
Ozone Secretariat
Mr. K. M. Sarma
Executive Secretary
PO Box 30552 Nairobi
Tel: +254 2 623 885
Fax: +254 2 623 913

• UNEP Regional Office for Asia and Pacific (ROAP)
UN Building, Radjamnern Avenue
10200 Bangkok, Thailand
Tel: +66 2 280 60 88
Fax: +66 2 280 38 29

• United Nations Development Programme (UNDP)
1 United Nations Plaza
New York, NY 10017
United States
Tel: +1 212 906 5042
Fax: +1 212 906 6947
• World Bank
1818 H St., NW
Washington, DC 20433
United States
Tel: +1 202 477 1234
Fax: +1 202 522 3256

• United Nations Industrial Development Organization (UNIDO)
PO Box 300
A-1400 Vienna
Tel: +43 1 211 31 3782
Fax: +43 1 230 7449

• Multilateral Fund of the Montreal Protocol
1800 McGill College Avenue
27th Floor
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. 2001.

Schonfield, et al.1995. Under African Skies. Pesticide Action Network North America Regional Center. California.

U.S. Environmental Protection Agency Methyl Bromide Home Page,
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. France.

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 Environment Programme.

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 1994. Nairobi.

United Nations Environment Programme. 1991. Synthesis Report of Ozone Scientific Assessment Panel. Nairobi. November.

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.

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