Without a shadow of a doubt, the synthetic cannabinoids are the most hazardous class of RCs. In the 90s, ALL the big pharma companies found their own scaffold that they could patent. It's Ki might be known, but they have only been tested on cells. Some of them have metabolites that are mutagenic and there is SO MUCH low-quality stuff being made in which dimers, trimers & polymers (some with a MW over 600) mean you will not be inhaling this - it's too heavy to vapourize in a bong or spliff so, in fact, your smoking the compounds left after pyrolysis and a LOT of that is REALLY bad. In the late 18th century, it was said that you could tell which chemists had worked on nitroso compounds by looking at the obituaries. The pyrolysis compounds contain a LOT of nitroso compounds so this class isn't acutely toxic, it's a chronic toxins and you will know who indulged by the HUGE cancer rates.
I might add that US folks should read their law on cannabinoids. It just says 'any compound whose primary action is as a CB1 agonist'.... illegal. See, not a chemical named, only an action.
Do yourself a favour and smoke the plant material through a water-pipe. At least the heavy compounds drop out (look at that ring of black shit around the surface of the water. If seeing that doesn't convince you that it could cause emphysema, you need to read a bit more. Too few people will admit to their doctor that they smoke weed so we have no figures. We WILL have figures for both of the points I raise in 10 years and X lives. I'm no hippy BUT in this case, nature knows best.
