Dichloromethane (DCM)

DCM, Diklormetan

Name PRTR	Dichloromethane (DCM)
CAS no	75-09-2
Chemical formula	CH₂Cl₂

Dichloromethane is a chlorinated solvent and belongs to the group volatile organic compounds (VOC). Dichloromethane is also called methylene dichloride and is a colourless, volatile liquid with a sweet odour.¹

Uses

Dichloromethane is used as an industrial solvent and paint thinner. It may also occur in some aerosols and pesticides and is used in the production of photographic film.² In the past, the substance was used as an inhalation anaesthetic.³ Since 1993 it is prohibited to market consumer products containing dichloromethane in Sweden and using the substance is prohibited since 1996, unless given exemption.^{4 5}

Sources and transportation pathways

Dichloromethane does not occur naturally in the environment.⁶ The substance is emitted during use within the chemical and pharmaceutical industry.⁷ Emissions are mainly released to air as the substance evaporates quickly. In air, it undergoes photochemical degradation within a few months. Most dichloromethane that ends up in the environment turns into carbon dioxide. In water, the substance is degraded within a few days, and in soil it binds loosely to soil particles and evaporates thereafter to air. A small part may also travel to the groundwater and small amounts may be present in drinking water. The substance is not likely to accumulate in plants or animals.⁸

Effects on environment and health

Dichloromethane is not toxic to aquatic systems.⁹ The effects on terrestrial animals and birds are unknown but the substance is unlikely to bioaccumulate.¹⁰ It reacts with ozone, but since it also reacts with other substances in the lower atmosphere it does not affect the ozone layer significantly.¹¹ As a VOC, dichloromethane 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. Dichloromethane is also a greenhouse gas that contributes to the increased greenhouse gas effect^{12 13}. 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.^{14 15}

Inhalation of dichloromethane may cause dizziness and skin contact may cause burning and redness. The substance may be carcinogenic.¹⁶ A toxic and corrosive gas or fumes are formed if it is heated or combusted.¹⁷

International agreements and regulations

Dichloromethane is regulated by the EU Water Framework Directive (2000/60/EC). The presence of dichloromethane in product is regulated by EU REACH regulation (EC 1907/2006). The UN Protocol on PRTRs and the EU E-PRTR regulation regulate how data on dichloromethane emissions is made available.

As a VOC, dichloromethane 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).

----------------------------------------------------

¹ https://rib.msb.se/Portal/Template/Pages/Kemi/Substance.aspx?id=2681&q=diklormetan&p=1
² https://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=42
³ https://pubchem.ncbi.nlm.nih.gov/compound
⁴ http://solutions.3msverige.se/3MContentRetrievalAPI/BlobServlet?lmd=1358521167000&locale=sv_SE&assetType=MMM_Image&assetId=1319245894731&blobAttribute=ImageFile
⁵ https://www.kemi.se/hitta-direkt/lagar-och-regler/regler-som-endast-galler-i-sverige/nationella-begransningar-och-forbud/svenska-regler-om-klorerade-losningsmedel
⁶ https://www.atsdr.cdc.gov/ToxProfiles/tp14-c1-b.pdf
⁷ http://prtr.ec.europa.eu
⁸ https://www.atsdr.cdc.gov/ToxProfiles/tp14-c1-b.pdf
⁹ https://rib.msb.se/Portal/Template/Pages/Kemi/Substance.aspx?id=2681&q=diklormetan&p=1
¹⁰ http://www.npi.gov.au/resource/dichloromethane
¹¹ http://apps.sepa.org.uk/spripa/Pages/SubstanceInformation.aspx?pid=72
¹² http://www.ghgprotocol.org/sites/default/files/ghgp/Global-Warming-Potential-Values%20%28Feb%2016%202016%29_1.pdf
¹³ http://www.naturvardsverket.se/Sa-mar-miljon/Klimat-och-luft/Klimat/Darfor-blir-det-varmare/Andra-vaxthusgaser/
¹⁴ http://www.ipcc.ch/pdf/assessment-report/ar5/syr/AR5_SYR_FINAL_SPM.pdf
¹⁵ http://www.smhi.se/kunskapsbanken/klimat/vaxthuseffekten-1.3844
¹⁶ https://toxnet.nlm.nih.gov
¹⁷ https://rib.msb.se/Portal/Template/Pages/Kemi/Substance.aspx?id=2681&q=diklormetan&p=1