Chronic , excessive alcohol consumption entails structural changes in the liver , brain and other organs , and is associated with an increased risk of developing certain types of cancer. Ethanol metabolism leads to the formation of acetaldehyde and acetic acid. Acetaldehyde adducts with DNA and proteins , reduces the efficiency of DNA repair systems and also reduces the level of glutathione , a peptide involved in detoxification . When ethanol metabolism by cytochromes and by alcohol dehydrogenase and xanthine oxidase as free radicals.