It most certainly is. That's why your body processes it immediately and why you become intoxicated. I'm not saying I don't drink (I most certainly do), but to say it's not a poison is plain silly.
We've all heard of cirrhosis of the liver.......
The only way to consume alcohol in a sub-toxic potency is to never catch a buzz.
Oh come on. Tylenol, Advil (and every other drug) is also processed by the body as it tries to expel it. When ingested, they (and ethanol) are
impurities in our system, not
poisons. A near-lethal dose of these (or ethanol) would be considered a poison, since it could "destroy life or impair health."
http://dictionary.reference.com/browse/poison
Ethanol, in low doses (1-2 drinks/day) has shown to have actual health benefits, the most significant of which would be lowering the risk of CPD.
To get back to the discussion, the best info I could find on this subject is that "food-grade" CO2 is only dispensed from glass lined tanks, which would prevent damage in case there was a backflow of the dispensed beverage. Otherwise, the gasses are the same.
Further, on Airgas's website, the MSDS for their industrial gas is the same as for their food grade.