Propylene glycol (PG) poisoning is extremely rare - that's why the FDA rates it as generally regarded as safe. Ingested PG is either excreted in urine or metabolized to lactic acid and pyruvic acid, both of which are products of normal human metabolism.
PG is used as a solvent for the IV infusion of certain drugs. All or almost all of the cases of PG toxicity come from patients who are already medically compromised in some way who undergo IV infusion. These cases are very uncommon.
Personally, I wouldn't drink a glassful of PG based antifreeze but I wouldn't drink a glassful of the ethanol based antifreeze either.