Exactly. There hasn't been nearly enough research conducted on JWH to know.
Why not use just use regular marijuana instead of a synthetic strain?
Not everyone has access to normal marijuana which is a shame.
That said, (and this is being said without doing any research prior) I have read a couple scientific publications that a few of the JWH chemicals may possibly break down into possible cancer causing materials when smoked. That said, I dont know what the results of the study were, or which chemicals specifically were stated, or even if the cancer issue arose when the chemicals were smoked, or if the cancer issues still persisted when NOT vaporized. Like I said I don't feel like pulling up those articles right now. If you go to the Wikipedia page for some of the main JWHs, scroll down to the references and you will find them. Its possible (keep in mind I am going off of memory here) that the cancer issue arose because of the molecular make up of certain JWH chems, and there may be some cannabinoid RCs with different make-ups/shapes etc that would not cause the same problem.......
However, I still stand by everyone else in the thread: no one really knows and do NOT take what I wrote above as fact, do the research!
If you have access to regular marijuana I would recommend that, you can always vaporize it, and marijuana has ANTI-CANCER properties! (yay!) I have always preferred regular marijuana to any "spice" cannabinoid chemical. Edibles are also fun, long lasting, and work just as good if not better at pain relief.
Best wishes and luck to you and your relative who is looking for pain relief.