Storage old schleich figures in plastic bags

Hello I have all my old rare schleich figures storaged in LDPE (light density polyethylene) zip bags. What I read they can cause damage to paint because acid. What I heard better option is store them in polypropylene zip bags even museum using them for archival stuff.. What's your experience with this type of stuff? It happend to you that some plastic zip bag damaged your figure?

I have stored my models in these bags for years and never had any problems!