Well, Kitch asked for a chemist, here I am.
Propylene Glycol is the main chemical in most new antifreeze and here is the scoop from Wikipedia (there are no other Academic types around, right?)
HumansThe acute oral toxicity of propylene glycol is very low, and large quantities are required to cause perceptible health damage in humans; propylene glycol is metabolized in the human body into pyruvic acid (a normal part of the glucose-metabolism process, readily converted to energy), acetic acid (handled by ethanol-metabolism), lactic acid (a normal acid generally abundant during digestion), and propionaldehyde. Serious toxicity generally occurs only at plasma concentrations over 1 g/L, which requires extremely high intake over a relatively short period of time. It would be nearly impossible to reach toxic levels by consuming foods or supplements, which contain at most 1 g/kg of PG. Cases of propylene glycol poisoning are usually related to either inappropriate intravenous administration or accidental ingestion of large quantities by children
Here is the link if anyone wants to check out the references: http://en.wikipedia.org/wiki/Propylene_glycol
That being said, I would not recommend drinking it.
Old antifreeze was made using a similar compound, ethylene glycol. It can become toxic if you drink enough of it.
ToxicityMain article: ethylene glycol poisoning
Ethylene glycol is moderately toxic with an oral LDLO = 786 mg/kg for humans. The major danger is due to its sweet taste. Because of that, children and animals are more inclined to consume large quantities of it than of other poisons. Upon ingestion, ethylene glycol is oxidized to glycolic acid which is, in turn, oxidized to oxalic acid, which is toxic. It and its toxic byproducts first affect the central nervous system, then the heart, and finally the kidneys. Ingestion of sufficient amounts can be fatal if untreated.
I would feel safe eating from a UDS made using a drum that used to hold antifreeze. I would be a little more concerned about oil, what with all the polycyclic aromatic hydrocarbons (PAH's), but those burn. I am pretty sure the glycols burn too. They are alcohols. (just not the fun kind like ethanol
)A good burn or two should do it to the point that anything leaching out of the metal will be in the part per trillion range.
Sterling, got any extra drums? A UDS is in my future plans after I finish up my current project...a mini WSM type smoker using a tabletop grill and an Aluminum tamale pot. Should have that cooking a fattie this weekend. I will try to take pictures.