Thanks for the info. Did more reading about the different types of PVC. My concern was largely based on the smell of the enclosure; when I bought it, it was wrapped and sealed in plastic and probably had been for months so it really stank of silicone sealant.
Now a week later that's dissipated and there's just a slight plastic odour which will probably not be noticeable once the damp coca husk is in it.

Next problem is that it is less than 1 inch too big for the closet and position I wanted to put it in but I'm going to make it work somehow.