Hi,
What size pea gravel?
Can you post a photo?

I use " aquarium gravel" as a drainage base in my enclosures.
I would have to say is about 1/4" - 3/8" in diameter.

You can boil it.

Be sure the bag is not torn as you don't know what it may have been exposed to or stored near.

I believe Bill ( deranged chipmunk ) used gravel from Home Depot? I give him a shout.