Are you sure?
"Glycerol has very low toxicity when ingested; its LD50 oral dose for rats is 12600 mg/kg and 8700 mg/kg for mice" (LD50 means the amount in the blood that causes death in 50% of cases, by comparison ethanol has an LD50 of 7,060 mg/kg and vitamin C 11,900 mg/kg)
It is food grade...