Polypropylene is probably the least nasty of the bunch.
Probably.
When the BPA scare came I saw so many people switching to a different kind of plastic instead of stainless steel or glass. I just could not understand what people were thinking.
We live somewhere humid and have very young kids, their playroom is covered with a very big one of those loom hooked ones, it’s awesome for that because it’s so soft. Spills tends to come out of it pretty easily, the wool seems to be at least mildly hydrophobic.
They’re so much nicer than the plastic type, and seem durable so far (the thick flat weave type has been holding up well on our stairs).