Show me the evidence. I mean seriously how ridiculous is this statement, why would any sane dealer do that? UK stoners are connoisseur's, not idiots, they would spot bad weed in a puff, and nobody would buy it, the seller would be out of business in 5 minutes. Its not going to do much for the weight either. To my knowledge this story originates from a picture sent by an anonymous scientist to the pro cannabis charity 'Drug Scope' who seem to have fallen for it hook line and sinker. An anonymous scientist who remains unwilling to back his findings up with personal disclosure is taken seriously by The Guardian, a paper with a political agenda, how laughable is that. Call me paranoid but, if there really was glass in your weed, assuming you looked under the microscope to verify your comments, I'd be asking, what have I done, for what reason would anyone put glass only in my weed. What else am I consuming that could be contaminated. If someone contaminated my weed I'd be straight back to the dealer for an explanation, what did your dealer have to say?