A current outbreak over 100 individuals sickened and at least three dead due to massive internal bleeding in the U.S. from  synthetic marijuana laced with rat poison has led to serious questions as to how or why this might have happened.  I have not seen anything written about reasons why such mixtures would occur or a case report (yet) in native marijuana, but recent relevant articles from some environmentalist/animal rights groups about use of rodenticides in some marijuana farms give me suspicions on how it could actually happen in naturally grown marijuana.   It is known that some marijuana crops farmers have used brodifacoum, the active ingredient in most rat poisons, in order to prevent rats from eating their prized marijuana crops.  The reason environmental and animal activist groups have raised concerns is due to the effects particularly on the upper food chain:  rats eat the poison, birds eat the rats, on and on.  Owls in particular have been reportedly killed as  a consequence of this.  One consideration that I raise is that the intended product perhaps gets grossly contaminated during the harvest process and mixed in. Keep in mind this business practice (at least while is illegal in some states) is often handled by less than knowledgeable people without quality processes in mind.   It just so happens that most rat poisons that I have encountered containing  brodifacoum do actually have a similar green color, but it is really a bit more teal or blue-green.   It remains to be seen what the source and cause of this dangerous marijuana blend may  be, but it certainly is not something that adds to the “high”.  The use by some marijuana farmers to protect the crops from rats seems to me to be the most likely culprit.   Sickening and or killing the end users certainly does not sound like an intentional business plan. But you never know.