Marijuana users had higher rates of emphysema than tobacco-only smokers
                                
                                
                                    (Newser) -
                                    A new study is countering the "public perception that marijuana is safe" or at least "safer than cigarettes," says author Giselle Revah, a radiologist at the Ottawa Hospital General in Canada's capital. As  ABC News  reports, rates of emphysema, airway inflammation, and enlarged breast tissue were...