Some PT may content PVC in their surface, a Beilstein test is needed in order to confirm it.
But apart that, its the most stable plastic around.
An as any storage material, there’s pro’s and con’s. And as any plastic, its more suitable to humidity retention if there’s a fluctuation donc it must be used in an HR controled place only.
Mylar-d is the PT made by Dupont, and theoricly it doen’t containt any PVC traces. But a lot of providers call their PT as Mylar too even if its not the case.
There’s a lot of info around about using PT in storage, you may want to check the AIC Wiki and googling around a little.