Dichloromethane Profile

INDUSTRIAL CHEMICALS – PROBABLE CARCINOGEN (IARC 2A)

CAS No. 75-09-2
IARC Monograph Vol. 71, 1999 (Group 2B)
IARC Monograph Vol. 110, 2017 (Group 2A)

Dichloromethane Profile

General Information

Dichloromethane is a volatile, clear, and colourless liquid with a smell similar to chloroform.[1] It has been an important industrial solvent since the 1940s.[2] Dichloromethane is also commonly referred to as methylene chloride and DCM.[3] There are numerous other synonyms and product names; see the Hazardous Substances Data Bank (HSDB) for more information.[3]

Dichloromethane is classified by the International Agency for Research on Cancer (IARC) as Group 2A, probably carcinogenic to humans, based on limited evidence that it causes biliary-tract cancer and non-Hodgkin lymphoma in humans, and sufficient evidence of carcinogenicity in experimental animals (malignant lung and hepatocellular tumours in male and female mice).[2] This assessment also considered the strong mechanistic evidence that dichloromethane is broken down into reactive metabolites by an enzyme called glutathione-S-transferase T1 (GSTT1), and that this activity is strongly associated with genotoxicity in vitro and in vivo.[2]

The central nervous system is the primary target of acute inhalation exposure.[4] Respiratory effects and skin irritation have also been reported.[4]

Regulations and Guidelines

Occupational Exposure Limits (OEL) [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]

Canadian Jurisdictions OEL (ppm)
Canada Labour Code 50
BC 25
AB, ON, MB, NL, PE, NB, NS 50
NT, NU, SK 50
75 [stel]
QC 50 [em]
YT 200
250 [stel]
Other Jurisdiction OEL (ppm)
ACGIH 2018 TLV 50
ppm = parts per million
stel = short term exposure limit (15 min. maximum)
em = exposure must be reduced to the minimum
ACGIH = American Conference of Governmental Industrial Hygienists
TLV = threshold limit value

Canadian Environmental Guidelines

Jurisdiction Limit Year
Canadian Drinking Water Guidelines 0.05 mg/L 2017[20]
Ontario Ambient Air Quality Criteria 24-hour: 220 µg/m3
Annual: 44 µg/m3
(as ‘methylene chloride’)
2016[21]
Residential Indoor Air Quality Included under product aerosol recommendations
(adequate ventilation and intermittent used advised)
1987[22]
Cosmetic Ingredients Hotlist Not permitted in aerosol preparations 
(as “methylene chloride”)
2014[23]
Food Additives Permitted for Use CE – Carriers or Extraction Solvents 2016[24]
BC’s Contaminated Sites Regulation, BC Reg 375/96

Sets soil standards for the protection of human health:
Agricultural and low density residential sites: 250 μg/g
Urban park and high density residential sites: 500 μg/g
Commercial sites: 1,500 μg/g
Industrial sites: 40,000 μg/g

Sets vapour standards for the protection of human health:
Agricultural, urban park, residential use standard: 600 μg/m3
Commercial use standard: 2,000 μg/m3
Industrial use standard: 5,500 μg/m3
Parkade use standard: 5,000 μg/m3

2017[25]
mg/L = milligrams per litre
µg/m3= micrograms per cubic metre
µg/g = micrograms per gram
Dichloromethane was not included in other Canadian government environmental guidelines reviewed.[26]

Canadian Agencies/Organizations

Agency Designation/Position Year
Health Canada DSL – low priority substance (already risk managed) 2006[27]
CEPA Schedule 1, paragraphs ‘a’ and ‘c’ 1999[28]
Environment Canada Pollution Prevention Plans – Part 4 of CEPA 1999 2000[29]
National Classification System for Contaminated Sites Rank = “High hazard”, potential human carcinogen 2008[30]
Environment Canada’s National Pollutant Release Inventory Reportable to NPRI if manufactured, processed, or otherwise used at quantities greater than 10 tonnes 2016[31]
Dichloromethane was not included in other Canadian government chemical listings reviewed.[32]
DSL = domestic substance list
CEPA = Canadian Environmental Protection Act

Main Uses

Dichloromethane is used to strip paint and remove varnish.[2] It has also been used as a flexible urethane blowing agent, in aerosol formulations, as a solvent in producing pharmaceuticals and film coatings, and as an extraction medium (used in the food industry to extract spices, caffeine, and hops).[1,4] Other uses include degreasing metals, manufacturing electronics and adhesives, processing plastics, and refrigerating.[4,33]

Historically, dichloromethane has been used as a fumigant. However, it is not currently registered as a pest-control product in Canada.[34]

Canadian Production and Trade

Canada does not produce dichloromethane, but meets domestic requirements through imports.[35]

Production and Trade

Activity Quantity Year
Canadian Production Not produced since 1985 2000[36]
Domestic Demand 5,100 t 2002[36]
Export 89 t of ‘dichloromethane (methylene chloride)’ 2015[37]
Import 3,064 t of ‘dichloromethane (methylene chloride)’ 2015[37]
t = tonne

Environmental Exposures Overview

An estimated 80% of dichloromethane produced globally is released to the environment.[38]

Based on data gathered in the early 1990’s, indoor air is likely the most significant source of exposure for Canadians.[39] CAREX Canada’s environmental estimates indicate that dichloromethane levels in indoor air result in an increased risk of cancer (moderate data quality).

Ambient air may be of greater concern in industrialized urban areas and in close proximity to waste or disposal sites.[1,38] CAREX Canada’s environmental estimates indicate that dichloromethane levels in outdoor air do not result in an increased risk of cancer (high data quality).

Environment Canada estimated that 2 million people were exposed to dichloromethane by using consumer products including paint strippers, aerosol paints, and insecticides and cleaning solutions.[35] Data on levels of dichloromethane in food is limited; however, it has been detected in several products including cereal and butter.[39,40] Potential for bioaccumulation in foods is low.[40] Dichloromethane levels are below the detection limit in the majority of drinking water samples collected in Canada, and are more frequently associated with groundwater sources.[40,41] Total daily intakes of dichloromethane for the Canadian general population are estimated to range from 3.96 to 6.62 micrograms/kilogram of body weight per day.[39] No recent Canadian studies have been identified for dichloromethane estimates in food and beverages.

Soil data on dichloromethane levels is limited to contaminated sites.[39,40] Dichloromethane has been detected in groundwater in Canada, and is usually associated with nearby landfills and waste disposal sites.[39]

Searches of the National Pollutant Release Inventory (NPRI) and US Household Products Database yielded the following results on current potential for exposure to dichloromethane in Canada:

NPRI and US Household Products Database

NPRI 2015[42]
Search term: ‘dichloromethane’
Category Quantity Industry
Released into Environment 20 t Office furniture manufacturing,
pharmaceutical and chemical manufacture,
pulp and paper mills,
paint, coating and adhesive manufacturing
(24 facilities)
Disposed of 328 t
Sent to off-site recycling 267 t
US Household Products 2015[43]
Search Term Quantity Product Type
‘Methylene chloride’ 55 Heavy-duty automotive cleaners and degreasers (11),
paint and adhesive remover (39),
paint brush cleaner (2), furniture cleaner (1),
deglosser (1), and herbicide (1)
t = tonne

For more information, see CAREX Canada’s environmental exposure estimate for dichloromethane.

Occupational Exposures

Inhalation is the most important route of occupational exposure, however dermal absorption is also possible.[1]

CAREX Canada estimates that approximately 25,000 Canadians are exposed to dichloromethane in their workplace. The largest industrial groups exposed are automotive repair and maintenance, followed by building finishing contractors and plastic product manufacturers. Other important industries that are likely exposed include paint removal, personal and household goods maintenance and repair, and automotive parts manufacturing.

The largest exposed occupational groups are motor vehicle body repairers, followed by painters and decorators, and machinists and machining and tooling inspectors. Other occupations that may be exposed include furniture refinishers and chemical  manufacturers.[1] Workers may be exposed when spraying urethane foam, removing paint or varnish from equipment or furniture, or using products that use dichloromethane as a propellant or degreasing agent.

For more information, see the occupational exposure estimate for dichloromethane.

Sources

1. National Toxicology Program (NTP). 14th Report on Carcinogens for Dichloromethane (2016) (PDF)
2. International Agency for Research on Cancer (IARC). Monograph summary, Volume 110 (2016) (PDF)
3. US National Library of Medicine. Hazardous Substances Data Bank (HSDB) (Search term: ‘dichloromethane’)
4. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for dichloromethane/methylene chloride(2000) (PDF)
10. Government of Newfoundland and Labrador. Regulation 5,12 Occupational Health and Safety Regulations (2012)
11. Government of the Northwest Territories. Occupational Health and Safety Regulations, R-039-2015 (2016) (PDF)
13. The Canadian Legal Information Institute (CanLII). Government of Nunavut’s Occupational Health and Safety Regulations, Nu Reg 003-2016 (2010)
15. Government of Prince Edward Island. Occupational Health and Safety Act Regulations Chapter 0-1 (2013) (PDF)
17. Government of Saskatchewan. The Occupational Health and Safety Regulations, 1996 (2016) (PDF)
18. The Canadian Legal Information Institute (CanLII). Yukon’s Occupational Health Regulations, O.I.C. 1986/164 (2012) (PDF)
19. Occupational Safety and Health Administration (OSHA). Annotated PELs (2018)
21. Ontario Ministry of the Environment and Climate Change. Ontario’s Ambient Air Quality Criteria (2016)
23. Health Canada. Cosmetic Ingredient Hotlist (2014)
25. Government of British Columbia. Contaminated Sites Regulation B.C. Reg. 375/96 (2017)
26. Alberta Environment and Parks. Ambient Air Quality Objectives (2017)
27. Health Canada. Prioritization of the DSL (2006)
28. Environment and Climate Change Canada. CEPA List of Toxic Substances (1999)
29. Environment and Climate Change Canada. Pollution Prevention (P2) Plans (2008)
30. Canadian Council of Ministers of the Environment (CCME). National Classification System for Contaminated Sites (2008) (PDF)
33. European Chlorinated Solvent Association. Methylene Chloride White Paper (2007) (PDF)
34. Health Canada. Pesticide Label Search (2016)
36. CPI Product Profile: Camford Information Services: Methylene Chloride (2000)
37. International Trade Centre. TradeMap (Free subscription required)
41. Conestoga-Rovers & Associates. Drinking Water Survey for New Parameters of Interest/Concern (2014) (PDF)
42. Environment and Climate Change Canada. National Pollutant Release Inventory (NPRI Facilty Search (Substance name: ‘Dicholoromethane’)
43. US National Library of Medicine. Household Products Database (HPD) (Search term: ‘Dicholoromethane’)

Other Resources

  1. Long, G. et al. “Dichloromethane: evaluation of risks to health from environmental exposure in Canada.” J. Geophys. Res.1994;12(2):305-318.
  2. Moore, R.M. “Dichloromethane in North American Waters.” Journal of Geophysical Research 2004;109:C09004.
  3. Environment and Climate Change Canada. Frequently Asked Questions: Pollution Prevention Planning Requirements for Dichloromethane (2010)
  4. Agency for Toxic Substances and Disease Registry (ATSDR). ToxFAQs Sheet for dichloromethane/ methylene chloride (2001) (PDF)

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