sorry, i totally didnt even respond to your question did i.
Personally i dont think youd have to worry about your cannabis being adulterated, i know it happens, but its much less common than its made out to be. What i WOULD worry about it, is someone with a lowered immune system inhaling burning plant matter. Even that is not good for someone with an elevated immune system!
Im a big fan of extracts, purely for the reason that you need less to get you where you want to be, which means less harmful byproducts in the process.
Eating cannabis seems like a good choice too. Do you guys have any type of cannabis, medically produced or grown for medicine in the UK? Im from Canada, so our laws differ.