The greatest exposures
to acetaldehyde of the general population may occur via inhalation
of contaminated ambient air as well as tobacco smoke. Ingestion
and skin contact are other possible routes. Acetaldehyde exists
in the ambient air as a by-product of combustion as well as
a pollutant caused by certain industrial processes. As noted
above, it is also contained in cigarette smoke.
Symptoms of exposure to acetaldehyde
include eye, nose and throat irritation; skin burns; dermatitis;
conjunctivitis; cough; central nervous system depression;
and delayed pulmonary edema (NIOSH). In animals, it is known
to produce kidney, reproductive, and teratogenic effects (NIOSH).
According to the Hazardous Substance Database, acetaldehyde
is less irritating but is a stronger central nervous depressant
An IARC study indicates that acetaldehyde
is a toxic metabolite formed in the mammalian liver during
the oxidation of ethanol. The acetaldehyde is converted to
acetyl coenzyme A, which is then oxidized through the citric
acid cycle or utilized in various anabolic reactions involved
in synthesis of cholesterol, fatty acids, and other tissue
In humans, at low levels of exposure,
acetaldehyde is rapidly absorbed and metabolized.
Acetaldehyde has been classified as
Class B2: Probable Human Carcinogen by the United States Environmental
Protection Agency and as a Group 2B: Possibly Carcinogenic
to humans by the International Agency for Research on Cancer.
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Last Updated: 1/31/03