Alcohol is an example of a chemical carcinogen. The World Health Organization has classified alcohol as a Group 1 carcinogen.[33] In Western Europe 10% of cancers in males and 3% of cancers in females are attributed to alcohol.[34] Worldwide, 3.6% of all cancer cases and 3.5% of cancer deaths are attributable to alcohol.[35] In particular, alcohol use has been shown to increase the risk of developing cancers of the mouth, esophagus, pharynx, larynx, stomach, liver, ovaries, and colon.[36] The main mechanism of cancer development involves increased exposure to acetaldehyde, a carcinogen and breakdown product of ethanol.[37] Other mechanisms have been proposed, including alcohol-related nutritional deficiencies, changes in DNA methylation, and induction of oxidative stress in tissues.[38]