PEG = Polyethylene Glycol but PG can equal Propylene Glycol and PPG is Poly Propylene Glyol. The Ethylene derivatives are more toxic than the Propylene derivatives. EG = Ethylene Glycol. Propylene derivatives are safe even as food additives but the Ethylene derivatives are deadly poisons and cause kidney failure.

I am not sure how the polymers stack up vs the monomers of these glycols regarding overall toxicity.