"The liver is responsible for the elimination - through
metabolism - of 95% of ingested alcohol from the body. The remainder of the alcohol is
eliminated through excretion of alcohol in breath, urine, sweat, feces, milk and saliva.
The body uses several different metabolic pathways in its oxidation of alcohol to
acetaldehyde to acetic acid to carbon dioxide and water.
Healthy people metabolize alcohol at a fairly consistent
rate. As a rule of thumb, a person will eliminate one average drink or .5 oz (15 ml) of
alcohol per hour. Several factors influence this rate. The rate of elimination tends to be
higher when the blood alcohol concentration in the body is very high or very low. Also
chronic alcoholics may (depending on liver health) metabolize alcohol at a significantly
higher rate than average. Finally, the body's ability to metabolize alcohol quickly tend
to diminish with age."
http://www.intox.com/physiology.asp