| Agent Name |
Methylene chloride |
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| Alternative Name |
Dichloromethane |
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| CAS Number |
75-09-2 |
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| Formula |
C-H2-Cl2 |
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| Major Category |
Solvents |
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| Synonyms |
DCM; Methylene di- (or bi-) chloride; Dichloromethane; [NIOSH] |
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| Category |
Chlorinated Aliphatic |
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| Description |
Colorless liquid with a chloroform-like odor. [Note: A gas above 104 degrees F.] [NIOSH] |
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| Sources/Uses |
Used as a paint stripper and an extraction solvent; [LaDou, p. 510] Also used as a blowing agent for polyurethane foam and a propellant for insecticides; [ATSDR Medical Management] No longer used as a fumigant in the U.S. [EPA Pesticides] |
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| Comments |
Evidence of liver injury in exposed workers has been reported. Some of the methylene chloride absorbed is metabolized to carbon monoxide. Non-smoking workers exposed to average concentrations of 66 ppm had carboxyhemoglobin levels of 3.6 %. This is above that permitted for exposure to carbon monoxide (3.5 %). [ACGIH] Dichloromethane causes "trivial hepatotoxicity, unless exposure is very heavy or agent ingested." [Zimmerman, p. 333] "In one study, 24 healthy workers chronically exposed to methylene chloride at concentrations averaging from 60 to 475 ppm were electrocardiographically monitored and showed neither an increase in ventricular or supraventricular ectopic activity nor episodic ST segment depression. Likewise, there was no evidence of cardiac susceptibility or electrographic abnormalities in several case reports of otherwise healthy persons rendered unconscious from acute exposure to methylene chloride." [ATSDR Case Studies #3] Methylene chloride is in the list of "Some volatile substances which may be abused by inhalation" published on the web site of the U.N. International Drug Control Programme, indicating its potential to cause narcosis in workers. [Flanagan et al. Volatile Substance Abuse] |
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| Restricted |
The methylene chloride standard (29 CFR 1910.1052) requires medical surveillance when the worker is exposed at or above the action level for 30 or more days per year, or at or above the STEL for 10 or more days per year. |
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| Reference Link |
OSHA Technical Links: Methylene Chloride |
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| Exposure Assessment |
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| BEI |
Dichloromethane in urine = 0.3 mg/L at end of shift; |
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| Skin Designation (ACGIH) |
No |
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| TLV (ACGIH) |
50 ppm |
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| PEL (OSHA) |
25 ppm, STEL(OSHA) = 125 ppm |
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| IDLH (NIOSH) |
2300 ppm |
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| Excerpts from Documentation for IDLHs |
Human data: Volunteers exposed at 1,000 ppm for 2 hours had carboxyhemoglobin levels in excess of those permitted in industry from exposure to carbon monoxide alone [Stewart et al. 1972]. A 10�minute exposure at 2,330 ppm has produced vertigo [Lehmann et al. 1936]. However, it has also been reported that no feeling of dizziness was noted after 1 hour of exposure to 2,300 ppm [Sax 1975]. It has been stated that no dizziness, but slight nausea, is caused by exposure to 2,300 ppm for 1 hour and that methylene chloride is not lethal at 25,000 ppm [Thienes and Haley] |
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| Vapor Pressure |
350 mm Hg |
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| Odor Threshold Low |
1.2 ppm |
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| Odor Threshold High |
440 ppm |
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| Lethal Concentration |
LC50 (mice) = 14,400 ppm/7H |
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| Explanatory Notes |
Detection odor threshold from AIHA (mean = 160 ppm); |
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| Half Life |
For carboxyhemoglobin in blood: 12-16 hours; [TDR, p. 862] |
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| Reference Link |
ATSDR Medical Management - Methylene Chloride |
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| Flammability (NFPA) |
1: must be preheated |
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| Adverse Effects |
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| Neurotoxin |
CNS Solvent Syndrome |
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| Hepatotoxin |
Hepatotoxin, Secondary |
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| IARC Carcinogen |
Possible Carcinogen |
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| Links to Other NLM Databases |
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| Health Studies |
Human Health Effects from Hazardous Substances Data Bank: DICHLOROMETHANE
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