I once committed the insanity of trading a bunch of key and semikey coins I had found in circulation for Capital plastic holders. One problem I had with the Capital holders was upgrading coins. Any time I wanted to exchange a coin for a better one, I had to take out several little plastic screws, rotate the top layer, and so on. The reason I said insanity is that the used holders were essentially worthless, whereas all the great coins I traded for them had gone up in value. This doesn't have anything to do with the OP's question, but it's cathartic for me to tell the story.
It's the glue, the paper, and the cardboard - all 3 of them put off gasses that are harmful to coins. And then of course there's the paper and cardboard dust that both produce.