Acetaldehyde is a substance that is produced in the human body during metabolic processes, for example when the body breaks down alcohol. This substance often occurs in nature as a chemical by-product in plants and in many organisms. It is also a natural ingredient in many foods, such as fruit, coffee and bread. The taste of acetaldehyde is described as fresh with a fruity but sometimes musty odour.

Acetaldehyde is widely used in the production of other industrial chemical substances. It is used as a solvent in the rubber, tanning and paper industries, and as a preservative for fruit and fish. Sometimes it is also used as a flavouring agent.

Acetaldehyde in tobacco smoke

Acetaldehyde is not added to cigarettes by tobacco producers. Rather, acetaldehyde is produced when tobacco additives (such as sugars, sorbitol and glycerol) are burned, and is released in cigarette smoke. The smoke directly inhaled by smoking a single cigarette contains an average of 1 microgram of acetaldehyde. However, some cigarettes can produce twice as much. This makes acetaldehyde one of the main components of cigarette smoke (after tar, nicotine and carbon monoxide).

Adverse health effects

Acetaldehyde is very reactive and is known to react with many other substances in the body. The substance causes irritation of the airways and has been classified as a possible carcinogen by the International Agency for Research on Cancer (IARC, a leading institute for cancer research).

Effect on smoking addiction

Acetaldehyde increases the addictive effect of nicotine, the substance in tobacco that is principally responsible for making smokers dependent on cigarettes. Acetaldehyde can thus cause damage indirectly because it can create a dependency on smoking. This may expose smokers to greater amounts of toxic substances in tobacco smoke.

Acetaldehyde can also indirectly make cigarettes more attractive. This is due to the effect harman, one of the reaction products of acetaldehyde, on the brain. It is assumed that harman has an effect similar to that of antidepressants on a person’s mood. Its mood-improving effect can thus increase dependence on smoking.