it is another solvent, like water, only it dissolves different things than water(and some the same). i think that is why studies have shown that one or two drinks per day may actually be of benefit. its the increased circulation.
but the studies also show that these benefits go away after two drinks and veer almost immediately into the detrimental zone. this is the dehydrating effects of alcohol, in my opinion. there is excessive drinking(judgment/safety issue) and alcohol poisoning, but the dehydrating effects are the worst chronic condition for your health if you drink moderately to heavy on a daily basis.
alcohol is a normal substance in the body, just not in very detectable amounts in the blood. BAC or blood alcohol content is a sign of how much alcohol is getting to the brain and we all know what that does.