Chloroform (Trichloromethane)

Kloroform, Kloroform (Triklormetan, CHCl3)



CAS no


Chemical formula


 Trichloromethane is also known as chloroform, formyl trichloride or methane trichloride, of which chloroform is the most common name. Trichloromethane is a chlorinated organic substance and belongs to the group volatile organic compounds (VOC). It is a colourless, volatile liquid with a sweet odour. The substance is non-combustible and has low solubility in water.1


In the past, trichloromethane has been used as an anaesthetic during surgery. Today it is used in industry in production of other chemicals and as a solvent as well as in laboratory work.2 3 It is prohibited to market trichloromethane to the general public in concentrations exceeding 0.1 mass percent and to use the substance in ways that result in exposure.4

Sources and transportation pathways

Trichloromethane is formed naturally in sea water, in soil and during volcanic and geologic activity. About 90 percent of all trichloromethane in the environment is of natural origin. The largest anthropogenic source is the use of strong oxidising agents which can result in formation of trichloromethane.5

Other emissions of trichloromethane occur from industries producing or using the substance. The largest point sources within Europe include facilities within the chemical industry and the pulp and paper industry.6

Because of its high volatility, trichloromethane evaporates quickly to the air. In the air it degrades slowly forming toxic and corrosive substances. In soil, trichloromethane may travel to groundwater.7

Effects on environment and health

In the event of large amounts of trichloromethane being released to the environment, such as during an accident, it may harm the environment. As a VOC, trichloromethane can be involved in the formation of ground-level ozone. Ground-level ozone may damage vegetation and during episodes of elevated VOC levels, it may cause irritation of the respiratory tract in humans. Because of its low degradability in air, it can travel long distances.8. Trichloromethane is toxic to aquatic organisms, it is an endocrine disruptor and it is biomagnified in nature.9 It is also a greenhouse gas that contributes to the increased greenhouse gas effect10 11. The increased greenhouse gas effect results in an increase of the average temperature on earth, which for example leads to climate change and rising of the sea level.12 13

Exposure to high levels of trichloromethane for a short period of time may cause dizziness, fatigue and headache. Exposure to high levels during a longer period of time may harm the liver, kidneys and nervous system. High exposure through skin contact may cause sores. Trichloromethane is likely to be carcinogenic.14

International agreements and regulations

Trichloromethane is regulated by the EU Drinking Water Directive (98/83/EC) and the EU Water Framework Directive (2000/60/EC). The presence of trichloromethane in products is regulated by the EU regulation on cosmetic products (EC 1223/2009) and the EU REACH regulation (EC 1907/2006). The UN Protocol on PRTRs and the EU E-PRTR regulation regulate how data on trichloromethane emissions is made available.

As a VOC, trichloromethane is indirectly regulated by the UN Convention on Long-Range Transboundary Air Pollution (CLRTAP) and the UN Framework Convention on Climate Change (UNFCCC), as well as by the EU National Emissions Ceilings Directive (2001/81/EC) and the EU Industrial Emissions Directive (2010/75/EU).