Vital Ozone Graphics 3

02 the culprits Methyl bromide, a substance used in agriculture, and also in food processing, accounts currently for about 10 per cent of ODS consumption. Asapesticide it iswidelyused tocontrol insect pests,weedsand rodents. It is used as a soil and structural fumigant too, and for commodity and quarantine treatment. Methyl bromide is manufactured from natural bromide salts, either found in underground brine deposits or in high concentrations above ground in sources such as the Dead Sea. methyl bromide 12

As the Montreal Protocol controls methyl bromide, emis- sions have declined significantly over the past decade. In non-Article 5 countries, the phase-out date was 2005, while Article-5 countries are allowed to continue produc- tion and consumption till 2015. The challenge is to elim- inate its use by gradually phasing out the amounts still allocated to a small number of non article-5 countries for critical uses. Both chemical and non-chemical alternatives to methyl bromide exist, and several tools can manage the pests currently controlled with methyl bromide. Research on al- ternatives continues, it being necessary to demonstrate the long-term performance of alternatives and satisfy risk concerns. As with CFC alternatives, researchers must show that alternative substances do not harm the ozone layer or heat up the atmosphere. This is the case for sulfu- ryl fluoride (SF), a key alternative to methyl bromide for the treatment of many dry goods (in flour mills, food process- ing facilities and for household termite control). Past pub- lications indicated that SF has a global warming potential of about 4,800, a value similar to that of CFC-11.

When used as a soil fumigant, methyl bromide gas is usually injected into the soil to a depth of 30 to 35 cm before planting. This effectively sterilizes the soil, killing the vast majority of organisms there. Strawberry and tomato crops use the most methyl bromide. Other crops for which this pesticide is used as a soil fumigant include peppers, grapes, and nut and vine crops. When used to treat commodities, gas is injected into a chamber containing the goods, typically cut flowers, veg- etables, fruit, pasta or rice. Methyl bromide is also used by bakeries, flour mills and cheese warehouses. Imported goods may be treated as part of the quarantine or phytosanitary measures in destination countries (referred to as “quarantine and preshipment” applications). In any application, about 50 to 95 per cent of the gas ultimately enters the atmosphere. Methyl bromide is toxic. Exposure to this chemical will affect not only the target pests, but also other organisms. Because methyl bromide dissipates so rapidly to the atmosphere, it is most dangerous at the fumigation site itself. Human exposure to high concentrations of methyl bromide can result in failure of the respiratory and central nervous systems, as well caus- ing specific, severe damage to the lungs, eyes and skin.


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