Hi Gustafson,
There aren’t any specific definitions for some of the criteria you are looking for so I would start with post #2 here which can help you decide which type of mattresses or materials are either “organic” or “natural” or “green” or “chemical free” or “safe” enough for you.
Once you have decided on the types of mattresses or materials that you are comfortable with having in your mattress … then the better options or possibilities I’m aware of in the Olympia area (subject to the guidelines here) are listed in post #5 here.
No … if it’s good match for you in terms of PPP then there is no reason that it wouldn’t be suitable for an adult as well.
Phoenix