MSD

The big problem with these is that since they're in a legal grey area, no active ingredients are disclosed and dosage varies. There are also a lot of people who bought the chemicals individually as powdered bulk product and determined their own dosages, which leads to problems because a gram of JWH-072, for example, is maybe 1/8 of a teaspoon in volume and is 30+ doses so a few grains can be the difference between a good high and a trip to the ER. They're almost all potent and specific cannabinoid agonists compared to the blend of natural cannabinoids you find in marijuana, whicih means smoking one dose of any particular one won't feel the same as smoking a bowl of weed, and they're more likely to trigger side effects; one common one I've heard of is people who are prone to seizures having them triggered by these synths because most of them are full GABA inhibitors. All of that comes together to lead to people easily smoking more than they should, getting more of the active compounds, and the negative effects feeling much more intense than things like classic weed-induced paranoia, racing heartbeat, etc.

Aside from that, these are all research chemicals with no studies done to find out what the short and long term health effects are. The solution to the problems with synthetic cannabinoids is simple: legalize marijuana.
Sounds like someone isn't thinking of the children.