I purchase some world coins from GovMint/New York Mint and they often come as shown. These are soft flips and I am concerned they may be harmful. I would hope the company knows better but often marketing companies do not think about that stuff.
There are a lot of dealers who routinely ship coins in the cheapest flips possible. Some of them may contain PVC and some may not. I would not trust any of them for storing coins. Whether or not it can affect paper, I can't say. Chris
The flea market that I sometimes pass by use those for their coins. On some of them they look cloudy, I'm not sure if thats a reaction to PVC though.