1791
T3D1787
Bromomethane
Bromomethane (or methyl bromide) is an organobromide compound that may be produced both synthetically and by naturally marine organisms and certain terrestrial plants. It was used extensively as a pesticide and as a fire extinguisher component until being phased out by most countries in the early 2000s, as it is considered an ozone-depleting substance. The primary use of methyl bromide is/was as a fumigant in soil to control fungi, nematodes, and weeds; in space fumigation of food commodities (e.g., grains); and in storage facilities (such as mills, warehouses, vaults, ships, and freight cars) to control insects and rodents. Its popularity as a fumigant is largely attributable to its high toxicity to many pests, the variety of settings in which it can be applied, its ability to penetrate the fumigated substances, and its rapid dissipation following application. Trace amounts of methyl bromide have been detected in drinking water. There are many reports of humans who have died following acute inhalation exposure to bromomethane. Most cases have involved accidental exposures associated with manufacturing or packaging operations, use of fire extinguishers containing bromomethane, or fumigation activities. Death is not immediate, but usually occurs within l-2 days of exposure. The cause of death is not certain, but is probably due to neurological and lung injury.
74-83-9
6323
CH3Br
93.941810
Colorless gas.
-93.7°C
15.2 mg/mL at 25°C
Oral (L626) ; inhalation (L626) ; dermal (L626)
Organobromide compounds such as bromomethane are strong alkylating agents. Consequently they can readily modify free thiols (cysteines) and methionine residues of the surfaces of proteins leading to the disruption of enzyme, transporter or membrane functions. The bromide ion (which is produced from bromomethane metabolism in the body) is known to affect the central nervous system, causing a condition called bromism. This is believed to be a result of bromide ions substituting for chloride ions in the in actions of neurotransmitters and transport systems, thus affecting numerous synaptic processes. (L626, L627, T104). However, the exact mechanism of toxicity for methyl bromide is currently uncertain, although its alkylating property as well as the reactive intermediates formed through metabolic transformation remain attractive hypotheses.
Bromomethane undergoes initial metabolism primarily by nucleophilic displacement of the bromide ion. When the attacking species is water, the products are methanol and bromide ion. Bromomethane may also react with organic thiols (R-SH) to yield S-methyl derivatives. This has been shown to result in formation of S-methylcysteine derivatives in hemoglobin of mice exposed to bromomethane. Further metabolism of methanol or S-methyl derivatives then leads to the formation of carbon dioxide.
LD50: 214 mg/kg (Oral, Rat) (T14)
LD50: 1540 mg/m3 over 2 hours (Inhalation, Mouse) (T14)
Lethality has been reported in humans following exposure to 60,000 ppm for 2 hours and 1,600-8,000 ppm for 4-6 hours.
3, not classifiable as to its carcinogenicity to humans. (L135)
The primary use of methyl bromide is as a fumigant in soil to control fungi, nematodes, and weeds; in space fumigation of food commodities (e.g., grains); and in storage facilities (such as mills, warehouses, vaults, ships, and freight cars) to control insects and rodents. In most places, levels of methyl bromide in the air are usually < 0.025 parts per billion (ppb). Industrial areas have higher levels (ranging up to 1.2 ppb) because of releases from chemical factories. Workers who fumigate homes and fields may be exposed to high levels of methyl bromide if proper safety precautions are not followed.
Bromomethane is highly toxic. Studies in humans indicate that the lung may be severely injured by the acute (short-term) inhalation of bromomethane. Acute and chronic (long-term) inhalation of bromomethane can lead to neurological effects in humans. Neurological effects have also been reported in animals. Degenerative and proliferative lesions in the nasal cavity developed in rats chronically exposed to bromomethane by inhalation. Chronic inhalation exposure of male animals has resulted in effects on the testes at high concentrations. Studies in humans indicate that the lung may be most severely injured by the acute inhalation exposure of bromomethane. The kidney is also sensitive to bromomethane. Anuria and proteinuria are common signs of renal injury in acutely exposed humans.
Breathing modest amounts of bromomethane may lead to the development of a headache, nausea and weakness after several hours. Breathing high concentrations of bromomethane may cause pulmonary edema, impairing respiratory function. Acute exposure by inhalation of bromomethane frequently leads to neurological effects in humans. Symptoms of acute exposure in humans include headaches, dizziness, fainting, apathy, weakness, confusion, speech impairment, visual effects, numbness, twitching, and tremors; in severe cases paralysis and convulsions are possible. Bromomethane is irritating to the eyes, skin, and mucous membranes of the upper respiratory tract. Dermal exposure to bromomethane can cause itching, redness, and blisters in humans. Neurological effects, including lethargy, forelimb twitching, tremors, and paralysis, have also been observed after chronic exposure to bromomethane.
EYES: irrigate opened eyes for several minutes under running water.
INGESTION: do not induce vomiting. Rinse mouth with water (never give anything by mouth to an unconscious person). Seek immediate medical advice.
SKIN: should be treated immediately by rinsing the affected parts in cold running water for at least 15 minutes, followed by thorough washing with soap and water. If necessary, the person should shower and change contaminated clothing and shoes, and then must seek medical attention.
INHALATION: supply fresh air. If required provide artificial respiration.
2009-06-22T16:08:36Z
2014-12-24T20:24:38Z
http://en.wikipedia.org/wiki/Bromomethane
C18447
39275
CPD0-1304
C005218
Bromomethane
BMM
848
true
CBr
CH3Br
InChI=1S/CH3Br/c1-2/h1H3
InChIKey=GZUXJHMPEANEGY-UHFFFAOYSA-N
94.939
93.941812743
Exogenous
Gas
1.19
HMDB31524
CHEMBL48339
6083