LABORATORY CHEMICAL SAFETY SUMMARY: ACETALDEHYDE

Substance

Acetaldehyde

(Ethanal, acetic aldehyde)

CAS 75-07-0

 

Formula

CH3CHO

 

Physical Properties

Colorless liquid

bp 21 °C, mp -124 °C

Miscible with water

 

Odor

Pungent, fruity odor detectable at 0.0068 to 1000 ppm (mean = 0.067 ppm)

Vapor Density

1.52 (air = 1.0)

 

Vapor Pressure

740 mmHg at 20 °C

 

Flash Point

-38 °C

 

Autoignition Temperature

185 °C

 

Toxicity Data

LD50 oral (rat)

661 mg/kg

 

LC50 inhal (rat)

20,550 ppm (37,000 mg/m3; 30 min)

 

PEL (OSHA)

200 ppm (360 mg/m3)

 

TLV-TWA (ACGIH)

100 ppm (180 mg/m3)

 

STEL (ACGIH)

150 ppm (270 mg/m3)

Major Hazards

Highly flammable liquid; irritating to the eyes and respiratory system.

Toxicity

The acute toxicity of acetaldehyde is low by inhalation and moderate by ingestion. Exposure to acetaldehyde by inhalation is irritating to the respiratory tract and mucous membranes; this substance is a narcotic and can cause central nervous system depression. Ingestion of acetaldehyde may cause severe irritation of the digestive tract leading to nausea, vomiting, headache, and liver damage. Acetaldehyde causes irritation and burning upon skin contact and is a severe eye irritant.

Acetaldehyde has caused nasal tumors in rats exposed by inhalation and is listed by IARC in Group 2B ("possible human carcinogen"). It is not classified as a "select carcinogen" according to the criteria of the OSHA Laboratory Standard. Acetaldehyde is mutagenic and has been shown to be a reproductive toxin in animals. Acetaldehyde is formed by metabolism of ethanol, and chronic exposure can produce symptoms similar to alcoholism.

Flammability and Explosibility

Acetaldehyde is a dangerous fire hazard (NFPA rating = 4) owing to its volatility and low autoignition temperature. Its vapor is explosive in the concentration range 4 to 66% in air and may be ignited by hot surfaces such as hot plates or light bulbs, or by static



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