I placed some empty HDPE plastic vitamin bottles in a sealed closet with moth balls, (naphthalene, d-diclorobenzne.) Years later I found the mothball smell had somehow gotten into the bottles, and no amount of airing them out would get rid of it. I assume the naphthalene etc. has actually been absorbed by the HDPE itself and is there to stay, no?
Come to think about it, it all makes sense: when deploying mothballs one can simply toss their plastic packages into the closet, not bothering to tear open their wrappers. The smell gets out of the bag and into the closet just about the same as if one tore them open.