Alcohol isn't just a toxin that your body eliminates; one of its effects are to override our excretion pathways. http://www.reddit.com/r/askscience/comments/24t7hr/at_what_p...
The science in this field is interesting. Poor test subjects had to drink a litre of 4% beer. http://alcalc.oxfordjournals.org/content/45/4/366.full