Agent Name

Methyl isocyanate

CAS Number

624-83-9

Formula

C2-H3-N-O

Major Category

Toxic Gases & Vapors

Synonyms

Iso-cyanatomethane; Isocyanate de methyle [French]; Isocyanate, methyl-; Isocyanic acid, methyl ester; Methane, isocyanato-; Methyl carbonimide; Methyl isocyanat [German]; Methyl isocyanat [German]; Methyl isocyanate; Methyl isocyanide; Methylcarbylamine; Methylisocyanaat [Dutch]; Methylisokyanat [Czech]; Metil isocianato [Italian]; TL 1450; [ChemIDplus] UN2480

Category

Monoisocyanates

Description

Colorless liquid with a sharp, pungent odor; [NIOSH]

Sources/Uses

Used in the production of insecticides, herbicides, polyurethanes, and other plastics; [ACGIH] Released from a pesticide factory in Bhopal India in 1984, killing about 2.500 people and leaving many survivors with chronic lung disease; [Rom, p. 503-4]

Comments

Methyl isocyanate can cause eye and skin injuries, pulmonary edema, and possibly immunological asthma. Skin sensitivity to methyl isocyanate developed in all sixteen guinea pigs tested. [ACGIH] Causes second and third degree burns after short skin exposures; [CHRIS] In high-dose reproductive studies of animals, methyl isocyanate decreases fertility and increases fetal losses and birth defects. Women exposed in the Bhopal disaster had higher rates of spontaneous abortions than controls. [Frazier, p. 344-5] A lachrymator; [HSDB] Methyl isocyanate is fibrogenic to the lungs in the context of an acute inhalation exposure complicated by bronchiolitis obliterans.

Reference Link

ATSDR Medical Management - Methyl Isocyanate

Exposure Assessment
Skin Designation (ACGIH)

Yes

TIH

Yes

TLV (ACGIH)

0.02 ppm

STEL (ACGIH)

0.06 ppm

PEL (OSHA)

0.02 ppm

MAK

0.01 ppm

Excerpts from Documentation for IDLHs

Lacrimation and irritation of the eyes, mucous membranes and skin; "Human data: Volunteers experienced eye irritation and lacrimation after 1 to 5 minutes at 2 ppm, with more marked irritation at 4 ppm; exposures were unbearable at 21 ppm [Kimmerle and Eben 1964]. In another study, volunteers noted eye irritation and lacrimation at 5 ppm in less than 50 seconds [Mellon 1963].

Vapor Pressure

348 mm Hg

Odor Threshold Low

2.1 ppm

Lethal Concentration

LC50 (rat) = 6.1 ppm/6 hr

Explanatory Notes

Odor threshold from AIHA; Flash point = -7 deg C;

Reference Link

ICSC: Methyl isocyanate

Adverse Effects
Skin Sensitizer

Yes

Lacrimator

Yes

Asthma

Yes

Toxic Pneumonitis

Yes

Fibrogenic

Yes

Reproductive Toxin

Yes

Dermatotoxin

Skin Burns

Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information

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Chemical Information

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Biomedical References

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Related Information in HazMap
Diseases

Occupational diseases associated with exposure to this agent: