What type of substance is it?
Chloromethane is both a common naturally occuring chemical and is manufactured by man, a colourless gas with a faint, sweet odour and a sweet taste. It is burns easily and is heavier than air. It is also a VOC (Volatile Organic Compound), which can contribute to the formation of harmful ground-level ozone.
How is it released?
Man-made chloromethane is released to air by chemical plants and during the burning of fuels. However, chloromethane is also a naturally occurring chemical formed in very significant amounts by marine algae and by rotting wood.
Detailed information
Scientific name:
Chloromethane; CH3Cl
Other names:
Methyl chloride, monochloromethane
CAS Number:
74-87-3
Other sources of chloromethane include cigarette smoke and polystyrene insulation. Some is also formed by the reaction between organic contaminants in water and chlorine used as a disinfectant - for example in swimming pools and water treatment works.
It is primarily used in the production of other chemicals such as silicones, agricultural chemicals and rubber. It was used in refrigerators in the past and appliances over thirty years old may still contain it.
Chloromethane is a colourless gas with a faint, sweet odour and sweet taste. It is slightly soluble in water and soluble in alcohol. The gas is flammable and heavier than air. When heated to decomposition it emits highly toxic fumes.
Where is it released?
Man-made chloromethane is released to air by chemical plants. However, chloromethane is also a naturally occurring chemical formed in very significant amounts by marine algae, by rotting wood. It is also released during the burning vegetation and coal.
Local environmental effects
There is little information available about potential local environmental effects of releases of chloromethane. Chloromethane is highly volatile, so that releases to land or water will rapidly evaporate. Degradation in water and soil is slow, so there may be the risk of transfer to groundwater. Chloromethane entering the lower atmosphere is slowly removed by chemical decomposition and upward diffusion. If released to water the majority will be lost by volatilisation with a river half life of a couple of hours. If released on land it will be rapidly lost by volatilisation. It may leach to groundwater where it will very slowly biodegrade or hydrolyse. As a VOC it can be involved in reactions with other air pollutants that form ground-level ozone, which can cause damage to crops and materials as well as having potential effects on human health.
Global environmental effects
No significant global impacts are considered likely.
Possible health concerns
Excessive exposure to chloromethane may affect the brain, eye, heart, kidney, liver, reproductive system and skin, and may cause cancer. The Environment Agency aims to ensure that environmental exposures are too low to harm human health.
Legislation
Why was this substance selected for the Pollution Inventory?
Included in : Environment Agency categorisation as a hazardous Volatile Organic Compound (VOC).
Standard risk phrases for the pure substance
The standard risk phrases provided here are generally those used by suppliers of chemicals to describe substances - for example on packaging materials. The most important source of these phrases are the CHIP Regulations - Chemicals (Hazard Information and Packaging for Supply) - provided by the Health and Safety Executive. Some substances do not have CHIP risk phrases and in these circumstances we have used other risk phrases, the sources of which are indicated.
CHIP Phrase(s) : F+: Extremely Flammable; Xn: Harmful; R12: Extremely Flammable; Carc Cat 3: R40: Possible risk of irreversible effects; R48/20: Harmful: danger of serious damage to health by prolonged exposure through inhalation
Controlling legislation and international agreements
Releases of chloromethane are controlled under the UK Pollution Prevention and Control Regulations, implementing the EC Directive on Integrated Pollution Prevention and Control (IPPC). As an organohalogen, chloromethane is regulated under many European and International agreements. In Europe chloromethane is controlled under the Hazardous Waste Directive. Internationally releases are regulated under OSPAR Convention and the 'Basel Convention on the Transboundary Movements of Hazardous Wastes and their Disposal'. As a VOC the main international legislation is the UN/ECE Convention on Long-Range Transboundary Air Pollution.
These factsheets have been compiled to provide users with information on the Pollution Inventory substances and represent our best efforts to summarise a large number of disparate and sometimes conflicting data sources. We emphasise that this information describes potential hazards rather than actual effects and that the Environment Agency seeks to regulate releases to minimise emissions and hence any risk of detrimental effects occurring.
