I've always been skeptical of this study. The water, filters out carcinogens. Thc is NOT water soluble, whatever thc loss there is, it's a moot point anyway because of how little, if anything is lost at all. It's definately cleaner, and healthier then a normal pipe, which is harsh as hell, and a joint, which is paper.. and blunt. Screw that study, experiance is my knowledge.