Agent Name

Methylene chloride

Alternative Name

Dichloromethane

CAS Number

75-09-2

Formula

C-H2-Cl2

Major Category

Solvents

Synonyms

DCM; Methylene di- (or bi-) chloride; Dichloromethane; [NIOSH]

Category

Chlorinated Aliphatics

Description

Colorless liquid with a chloroform-like odor. [Note: A gas above 104 degrees F.] [NIOSH]

Sources/Uses

Used as a paint stripper and an extraction solvent; [LaDou, p. 552] 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]

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]

Restricted

In US industries, the process use of methylene chloride ended in the mid-1990s; [PMID 24224613] Methylene chloride standard (29 CFR 1910.1052) requires medical surveillance if >action level >30 days/yr of >STEL >10 days/yr;

Reference Link

OSHA Technical Links: Methylene Chloride

Exposure Assessment
BEI

Dichloromethane in urine = 0.3 mg/L at end of shift;

Skin Designation (ACGIH)

Insufficient data

PEL (OSHA)

25 mg/m3, STEL(OSHA) = 125 ppm

MAK

50 ppm

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 10minute 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]

Vapor Pressure

350 mm Hg

Odor Threshold Low

1.2 ppm

Odor Threshold High

440 ppm

Lethal Concentration

LC50 (mice) = 14,400 ppm/7H

Explanatory Notes

Detection odor threshold from AIHA (mean = 160 ppm);

Half Life

For carboxyhemoglobin in blood: 12-16 hours; [TDR, p. 862]

Reference Link

ATSDR Medical Management - Methylene Chloride

Flammability (NFPA)

1: Must be preheated

Adverse Effects
Neurotoxin

CNS Solvent Syndrome

Hepatotoxin

Hepatotoxin, Secondary

IARC Carcinogen

Possible Carcinogen

NTP Carcinogen

Anticipated Human Carcinogen

ACGIH Carcinogen

Confirmed Animal

Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information

Search TOXNET

Chemical Information

Search ChemIDplus

Biomedical References

Search PubMed

Related Information in HazMap
Diseases

Occupational diseases associated with exposure to this agent:

Processes

Industrial Processes with risk of exposure:

Activities

Activities with risk of exposure: