Here's my 2 cents as a distiller and a MD. Heavy alcohol consumption, especially spirits, is linked to cancer of the esophagus and oral cavity. This is seen mainly in HEAVY alcoholics, not craft spirits tasters. Any alcohol you consume is metabolized by the ctyochrome p450 enzymatic system in your liver (same one used by Tylenol, so don't consume them together). Alcohol is a poison. If you consume a large volume you oustrip temporary capcity of the enzymes and get liver damage. In the short term this will be reflected by an increase in liver enzyme markers, mainly ALT. However, the liver has unbelievable regenerative capacity. Your can remove ~75% of someone's liver, and they should be able to regenerate enough capacity to have normal function. So how much is safe to drink? No one can tell you for sure, but studies have shown enzyme markers usually remain normal if you drink 2-3 drinks per day total (14-21/week). Personally, as a whiskeyphile and product taster, I have no worries about the volume of etoh I'm consuming, which by the way, is less than I remember drinking during highschool in the 80s.