Don't use Kiln dried ISPM15 wood either, the heat treatment allows the mould spores free reign in the correct environment.I noticed those shelves are MDF ,
I had some new shelving and their chipboard and went mouldy over the winter ,I did later notice it is recommended to varnish them if it going to be a moist atmosphere ,
It's on my too do list before next winter to coat them with varnish or more likely bedec barn paint ....
Might be worth doing before you fill the shelves ??