I have been doing a lot of reading about using concentrates and I have came across what seems like a lot of articles reporting that using concentrates is harmful to the brain and lungs, perhaps worst than smoking herbs traditionally. They say this is due to the butane and chemicals still left in the concentrates after it has been "blasted". From what I have read most concentrates still have a measurable amount of butane left in them. What's your take on possible health risks? Has anyone read anything from a credible source (doctor) explaining the real risks of using BHO's? Or do you think it's safe? Why? Lastly, is one form of BHO "cleaner" than the other? Wax vs budder vs shatter...what's "cleaner"? Why? Thanks!