In anycase, there is no clear information that mary is good or bad for you. Scientist will always find something different from each other.
One will say, Yes its dangerousnes out wieghs the benifits. And the other will say just the opposite.
Look on http://www.medicalmarijuanaprocon.org
. They give a non-biased view giving both the pros and cons to all subjects.
As in the Question "Is Mary a "Gateway/ stepping-stone" drug?"
Here is a PRO(no):
There is no evidence that marijuana serves as a stepping stone on the basis of its particular physiological effect. Much of their [U.S. drug-policy leaders] rhetoric about marijuana being a 'gateway drug' is simply wrong. After decades of looking, scientists still have no evidence that marijuana causes people to use harder drugs. If there is any true 'gateway drug,' it's tobacco.
And here is a Con (yes):
Individuals who used cannabis by age 17 years had odds of other drug use, alcohol dependence, and drug abuse/dependence that were 2.1 to 5.2 times higher than those of their co-twin, who did not use cannabis before age 17 years. Yes it is, the medical literature documents this and IOM understates it. Alcohol, tobacco and marijuana all have serious primary effects but all serve as gateway drugs.
So what ever you say, no one is ever right or wrong. We simply wont know becuase they will come out with different reports.