As an experiment I put a piece of unpainted, unfinished, MDF in a glass of water the other day. The MDF was about 1/4 inch tapering to 0 and about three inches long. I was thinking of making some necklace pendants from it and I wanted to see how it might hold up under sweat and humidity. I forgot about putting it in until the next week when I was able to get back into the shop. I pulled this sliver out of the glass again and it was slightly pliable but still rather strong and had not lost it's shape. I checked the flexibility and it was still firm although a little bendable but not in the thicker part.
I then dried it out to see how it worked. It was just like new cutting it and it still retained the original shape.
My opinion, for what it's worth, is that it will definitely hold up under the heat, humidity and use of being a wearable. I'll be doing some more!