I think that the smell is not plastic rotting but Stinkor who's gimmick is a kind of sweet and bitter bad chemical type smell. You won't die

You have a pretty decent collection there and most of it is MOTU. Some POP dolls but not too much. I was expecting the other way around.

Display them to air them out a bit and get rid of the Stinkor smell (although Stinkor is likely to retain his smell as it's infused in the plastic). Then see if you appreciate them and if not, start selling them.