Question is DID he use it, and is there definitive proof on it.
"On today's episode, Chris Aceto vigorously defends 2 x Mr. Olympia Derek Lunsford against accusations linking him to PMMA usage"
So for people who don't know what PPMA is, here is one definition from google...
"Site enhancement oil are compounds injected into muscles to increase their size. Synthol is injected into muscles to create larger bulges, or injecting Poly (methyl methacrylate) (PMMA) into muscles to shape them"