In October 2009, the International Agency for Research on Cancer (IARC), the international cancer research unit which forms part of the World Health Organization, classified acetaldehyde included in and generated endogenously from alcoholic beverages as a Group I human carcinogen.
Acetaldehyde belongs to the same risk class as, for example, asbestos and tobacco.
Specific microbes (bacteria and yeasts) in the gastrointestinal tract are the most important source of acetaldehyde exposure to the human body.These microbes produce acetaldehyde from alcohol and, in certain circumstances, from sugar. Unlike the liver, the microbes and the intestinal mucosa cannot remove the acetaldehyde, and due to the effect of alcohol, an abundance of acetaldehyde accumulates in the saliva and elsewhere in the gastrointestinal tract.
Acetaldehyde is a substance that accumulates in the body from several sources, continuous exposure to it thereby severely increasing the risk of cancer to various organs.