I used to scoop 1-oz portions onto a wax-paper-covered cookie sheet, then put the cookie sheet in the freezer. Once frozen, the 1-oz servings can then be put into a larger container & stored in the freezer.
Not sure if this helps or not, but neither ZipLoc nor Saran nor Glad bags contain BPA or PVCs (which I also try to avoid). I'm not sure, though, that we'll ever know what's in various plastics or how the chemical components influence our health over time.
When I've had questions about certain plastics & their BPA content, I've found a quick search <product or brand name> BPA to be effective. Not only does it turn up the manufacturer's site, but also other "watchdog" type organizations.