The negative effects listed are merely indicative of greater societal problems that are ongoing, while use of cannabis could be named as a factor, it would nonetheless be speculation as to whether the effects are deemed actual negative consequences is relative to the perception of the researcher.
The mental health speculation is determined by psychoanalytical questioning, which is not determined by any physical data other than a psychologist asking questions. Also diet is an inclusive factor in determining the outcome, which the diet is most likely overlooked as a key factor in the studies. All the more reason to explain the proper use to users of the herb and stop it with the unconvincing scare tactics.