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Methyl chloride

Methyl chloride

SPRI Emission Reporting Threshold
1,000 Kg/yr Pollutant Emissions to Air
Disclaimer
This sheet is a generic summary, designed to give the reader a basic level of background information about the substance in question. Great care has been taken to represent as effectively and correctly as possible the broad range of (not necessarily consistent) information which is available from a variety of sources. The reader must accept therefore that this sheet has no legal status and cannot be relied upon in any legal proceedings. SEPA disclaims any responsibility or liability whatsoever for errors and omissions in this sheet.
What is it?
Cloromethane is a colourless gas which has a faint, sweet smell and taste. It is heavier than air and is flammable. When heated, Cloromethane breaks down into very toxic fumes. Chloromethane dissolves slightly in water and well in alcohols. Chloromethane is one of a group of chemicals known as the volatile organic compounds (VOCs).
What is it used for?
Chloromethane is mainly used in the production of other chemicals such as pesticides and fertilisers, silicones and rubbers. In the past, it was also used as a refrigerant in domestic appliances. Appliances more than 30 years old may still contain it.
Where does it come from?
Chloromethane is released from man-made sources such as chemical plants and during the burning of fuels. Significant amounts are also released naturally by marine algae, rotting wood and natural fires. Trace amounts are found in cigarette smoke.
How might it affect the environment?
Little is known about the environmental impacts of Chloromethane. Due to the ease with which it evaporates, releases to land or water quickly end up in the atmosphere where it is slowly broken down. That which remains in soils or water will persist and may therefore end up in groundwaters. As a VOC, Chloromethane can be involved in the formation of ground level ozone which can cause damage to crops and materials. It is not considered likely that Chloromethane pollution has any effects on the global environment.
How might exposure to it affect human health?
Methyl chloride can enter the body either by inhalation of air containing methyl chloride, ingestion of water containing methyl chloride, or by dermal contact with liquid methyl chloride. Dermal contact mainly occurs in the occupational setting. Inhalation of air containing methyl chloride can lead to fatigue and drowsiness. Exposure to high levels of methyl chloride can effect the central nervous systems and may lead to a range of health effects including dizziness, fatigue, confusion, tremors, a lack of coordination, nausea, vomiting and in extreme cases coma and death. Ingestion of high levels of methyl chloride can result in nausea, abdominal pain, vomiting and diarrhoea. Dermal contact with liquid methyl chloride can lead to an allergic reaction in the form of a skin rash. The International Agency for Research on Cancer has designated methyl chloride as being not classifiable as to its carcinogenicity to humans. However, exposure to methyl chloride at normal background levels is unlikely to have any adverse effect on human health.
What steps are being taken to limit the potential impacts?
Releases of Chloromethane are controlled through the UK Pollution, Prevention and Control (PPC) Regulations. As a VOC, levels in air are also regulated through the UK National Air Quality Strategy. As an organohalogen, Chloromethane is regulated through a large number of European and international agreements. The main European legislation includes the EC Directive restricting the marketing and use of certain dangerous substances (76/769/EEC) and the Hazardous Wastes Directive (91/689/EEC), which protects groundwaters. The main international legislation includes the UN/ECE Convention on Long-Range Transboundary Air Pollution, the Basel Convention on the transboundary movement and disposal of hazardous wastes and the OSPAR Convention which protects the marine environment of the north-east Atlantic Ocean.