The breakdown of ethyl alcohol is as follows:

alcohol dehydrogenase ethyl alcohol -> acetaldehyde

aldehyde dehydrogenase acetaldehyde -> acetate

Much like formaldehyde, acetaldehyde is a toxic mutagen. Depending on your diet, genetics and the health of your liver, alcohol consumption can lead to an accumulation of acetaldehyde. This is why many asians get "red-faced" from drinking, they actually accumulate acetaldehyde due to their genetics. The other major toxin in many alcohols is methyl alcohol, which can break down into formaldehyde, but is actually pretty toxic on its own.

These are fun facts to share at drinking parties ;)