I haven't heard of anyone testing toxins on them, but I do remember there were toxins in the air at points that were related to one of them. I didn't stop to get details, but I do remember it.
There are also a lot of clinics around that may be able to take you on as apprentices.
Text; @IcyHot
There are also a lot of clinics around that may be able to take you on as apprentices.