Methyl bromide is a fumigant used against a wide range of pests, including spiders, ticks, fungi, plants, insects and rodents. Introduced as a pesticide in 1932. Methyl bromide fumigation is used to fumigate agricultural products, grain elevators, mills, ships, clothes, furniture and greenhouses.
Physical properties
Methyl bromide is a colorless gas or volatile liquid, which is usually odorless. In high concentrations, it may smell like chloroform. It is not spontaneous fuel, but is dangerous when exposed to sparks or flames. At increased pressure or at a temperature below 3 ° C methyl bromide assumes the state of a liquefied gas. It has a boiling point of 38.5 ° C and does not ignite in air. Contains chloropicrin.
Reaction to other substances
Methyl bromide is a serious explosion hazard when combined with aluminum, magnesium or zinc. Slow explosions can occur in the presence of dimethyl sulfoxide. A vigorous reaction occurs when mixed with strong oxidizing agents or ethylene oxide. The use of ethyl bromide is currently being reduced due to its ability to destroy the ozone layer.
Origin
It is made in a natural and synthetic way. The main sources of methyl bromide in the environment are oceans, biomass burning and fumigation. For the agricultural industry, it is made by reacting a methanol compound with hydrogen bromide.
How does it work?
Gas fills air spaces in enclosed spaces, penetrates into cracks and pores in the soil. Effective processing requires a certain concentration and optimal use time of methyl bromide.
Sources
In the atmosphere, the level of this gas is less than 0.025 parts per billion (ppd). Industrial areas have higher levels due to emissions from chemical plants.
Workers who smoke houses and fields can be exposed to high concentrations of methyl bromide if they do not follow proper safety rules.
An insignificant gas content was found in drinking water. A little methyl bromide is formed by ocean algae.
Using
Gas is a broad spectrum pesticide, mainly used for fumigation of soil, commodity or quarantine treatment and structural fumigation. It is also an intermediate in the manufacture of other chemicals.
In 2000, 71,500 tons of synthetic methyl bromide were used worldwide annually. About 97% was for fumigation purposes, 3% went to the manufacture of other products. In addition, developed countries accounted for 75% of consumption. Asia and the Middle East combined used 24%. In Latin America and Africa, the lowest percentage was 9%.
Methyl bromide use
In commercial large-scale monocultural seed production, it is vital to avoid contaminating crops with seeds of the same species, but of a different type. Therefore, selective herbicides cannot be used. In this case, methyl bromide treatment is much safer and more effective than other soil sterilizers.
In the past, this fumigant was used as a cooling agent in fire extinguishers. It is also used in the manufacture of other chemicals.
Methyl bromide is used to prepare golf courses. Farmers use it to till the soil in order to destroy nematodes, fungi and weeds.
To fumigate the soil, methyl bromide is introduced directly into the soil, which is then coated with tarpaulin materials. The tarp is sealed, kept in place for several days, and then removed. Such fumigation improves the quality of crops and increases productivity.
The main crops grown on cultivated soils are peppers, strawberries, tomatoes and grapes.
The inhalation effect on rodents harms not only adults, but also the future generation, preventing normal reproduction.
Fumigation of goods
Methyl bromide is widely used for fumigation of postharvest products, including wheat, crops, spices, nuts, dried fruits. This treatment helps eradicate pests. Fumigation is carried out in all rooms where products are stored. Commodity fumigation usually involves the use of specially designed and installed chambers in which methyl bromide is released.
After processing, the products are continuously ventilated using mechanical ventilation until the gas concentration reaches a safe norm. Another type of commercial fumigation involves sealing the product under a tarp with the subsequent introduction of methyl bromide. Ventilation is carried out after the tarpaulin is removed.
Fumigation of premises
All types of commercial and residential premises can be treated with methyl bromide to control and kill pests. They are covered with a "tent" or tarpaulin filled with gas. After a certain period, the material is removed. The rooms are thoroughly ventilated until the methyl bromide concentration reaches the norm.
Safety compliance
All persons working with gas should be aware of its dangers and trained in the use of personal protective equipment. Workers and other people in the fumigation area must be equipped with special equipment. If the concentration of methyl bromide in the work area exceeds established safety standards, then all persons in the fumigated area must wear a self-contained breathing apparatus.
Warning signs must be placed at all entrances to this area. No one is allowed into the room without personal protective equipment. Persons living in close proximity to fumigated fields, greenhouses, and rooms are unlikely to be exposed to unsafe levels of methyl bromide due to restrictions on use and the rapid dispersal of gas in the atmosphere.
Danger to people
At this point, scientists have studied in detail the nature of the toxic effect of methyl bromide on humans. Inhaling a high concentration of gas can cause pulmonary edema and damage respiratory functions. Acute inhalation of methyl bromide often leads to neurological consequences. It can be:
- headaches and dizziness;
- fainting, apathy, and weakness;
- confusion and speech impairment;
- visual effects;
- numbness, twitching, and tremor;
- in severe cases, convulsions and paralysis are possible.
Gas irritates the eyes, skin and mucous membranes of the upper respiratory tract. May cause itching, redness, and blisters. In some cases, kidney and liver damage was observed.