Бромметан: қасиеттері, қолданылуы және экологиялық аспектілер

Organobromine chemical compound
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|ImageFile = Natta projection of bromomethane. svg
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|ImageName = Stereo, skeletal formula of bromomethane with all explicit hydrogens added
|ImageFileL1 = Bromomethane 3D balls. png
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|ImageNameL1 = Ball and stick model of bromomethane
|ImageFileR1 = Bromomethane 3D vdW. png
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|ImageNameR1 = Spacefill model of bromomethane
|PIN = Bromomethane
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|REL = Ca From the chemistry perspective, it is one of the halomethanes.

Marine organisms are estimated to produce 56,000 tonnes annually. It is also produced in small quantities by certain terrestrial plants, such as members of the family Brassicaceae. In 2009, an estimated 24,000 tonnes of methyl bromide were produced. Its production was curtailed by the Montreal Protocol, such that in 1983, production was nearly twice that of 2009 levels. It is manufactured by treating methanol with bromine in the presence of sulfur or hydrogen sulfide: and almonds. Bromomethane is safer and more effective than some other soil sterilants. Its loss to the seed industry has resulted in changes to cultural practices, with increased reliance on soil steam sterilization, mechanical roguing, and fallow seasons. Bromomethane was also used as a general purpose fumigant to kill a variety of pests including rats and insects. Bromomethane has poor fungicidal properties. Bromomethane is the only fumigant allowed (heat treatment is the only other option) under ISPM 15 regulations when exporting solid wood packaging (fork lift pallets, crates, bracing) to ISPM 15 compliant countries. Bromomethane is used to prepare golf courses, particularly to control Bermuda grass. The Montreal Protocol stipulates that bromomethane use be phased out. Bromomethane is also a precursor in the manufacture of pharmaceuticals such as neostigmine bromide, pancuronium bromide, propantheline bromide], pyridostigmine bromide, atropine derivatives, clidinium bromide, clobazam, demecarium bromide, glycopyrrolate, and vecuronium bromide. It is a precursor to many ordinary chemicals often as a methylating agent. In 2003 the Global Environment Facility approved funds for a UNEP UNDP joint project for methyl bromide total sector phase out in seven countries in Central Europe and Central Asia, which was due for completion in 2007.

In Australia, bromomethane is the preferred fumigant of the Department of Agriculture and Water Resources for most organic goods imported into Australia. The department conducts methyl bromide fumigation certification for both domestic and foreign fumigators who can then fumigate containers destined for Australia. A list of alternative fumigants is available for goods imported from Europe (in what's known as the BICON database), where methyl bromide fumigation has been banned. Alternatively, the department allows containers from Europe to be fumigated with methyl bromide on arrival to Australia.

In New Zealand, bromomethane is used as a fumigant for whole logs destined for export. Environmental groups and the Green Party oppose its use. In May 2011 the Environmental Risk Management Authority (ERMA) introduced new rules for its use which restrict the level of public exposure to the fumigant, set minimum buffer zones around fumigation sites, provide for notification to nearby residents and require users to monitor air quality during fumigations and report back to ERMA each year. All methyl bromide fumigations must use recapture technology by 2025.

In the United States bromomethane is regulated as a pesticide under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA; 7 U. S. C. 136 et seq.) and as a hazardous substance under the Resource Conservation and Recovery Act (RCRA; 42 U. S. C. 6901 et seq. ), and is subject to reporting requirements under the Emergency Planning and Community Right to Know Act (EPCRA; 42 U. S. C. 11001 et seq.). The U. S. Clean Air Act (CAA; 42 U. S. C. 7401 et seq.). A 1998 amendment (P. L. 105 178, Title VI) conformed the Clean Air Act phase out date with that of the Montreal Protocol. Critical use exemptions allow the United States to continue using MeBr until it is scheduled to be completely phased out sometime in 2017.

Chile has phased out the use of bromomethane in traditional agriculture as of 2015, with exemption of the 100% pure formulation that is largely used for quarantine pest control and at pre shipments of the fruit export industry.

Alternatives to bromomethane in the agricultural field are currently in use and further alternatives are in development, including propylene oxide and furfural. For Australia, a list of alternative fumigants is available for goods imported from Europe (in what's known as the BICON database), where methyl bromide fumigation has been banned.

Iodomethane Exposure levels leading to death vary from 1,600 to 60,000 ppm, depending on the duration of exposure (as a comparison exposure levels of 70 to 400 ppm of carbon monoxide cover the same spectrum of illness/death). Concentrations in the range of 60,000 ppm can be immediately fatal, while toxic effects can present following prolonged exposure to concentrations well under 1,000 ppm. "A TLV–TWA of 1 ppm (3.89 mg/m3) is recommended for occupational exposure to methyl bromide" ACGIH 8 hour time weighted average. Immediately Dangerous To Life or Health Concentration by NIOSH: "The revised IDLH for methyl bromide is 250 ppm based on acute inhalation toxicity data in humans [Clarke et al. 1945]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 220 ppm. [Note: NIOSH recommends as part of its carcinogen policy that the "most protective" respirators be worn for methyl bromide at any detectable concentration.]" Detectable concentration by Drager Tube is 0.5 ppm. Respiratory, kidney, and neurological effects are of the greatest concern. Treatment of wood packaging requires a concentration of up to 16,000 ppm. NIOSH considers methyl bromide to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990]. "Methyl bromide showed a significant dose response relationship with prostate cancer risk."

Expression of toxicity following exposure may involve a latent period of several hours, followed by signs such as nausea, abdominal pain, weakness, confusion, pulmonary edema, and seizures. Individuals who survive the acute phase often require a prolonged convalescence. Persistent neurological deficits such as asthenia, cognitive impairment, optical atrophy, and paresthesia are frequently present after moderate to severe poisoning. Blood or urine concentrations of inorganic bromide, a bromomethane metabolite, are useful to confirm a diagnosis of poisoning in hospitalized patients or to assist in the forensic investigation of a case of fatal overdosage.