Since we were talking about how you could get brain damage from casual marijuana, did the Harvard study test for anything? It's the same story over and over again. "Health Care" professionals do not test for lead. All doctors who have to make it in a capitalistic system end up with conflict of interest issues.
You want conspiracy? How about Flint, MI?
https://www.youtube.com/watch?v=6QjLa6gyCBAThere are things that have yet to be revealed to the public:
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The Ethyl Controversy (PDF, 9.7 MB)by WJ Kovarik - 1993
... The breakthrough came in 1992, when I checked with what was then the General Motors Institute (now Kettering University) in Flynt, Michigan.[sic] I learned that 80 linear feet of “unimportant” archives from the office of leaded gasoline inventor Thomas A. Midgley Jr had been released only a few months beforehand. No one had taken the time to look through the mass of disorganized unclassified material. A former Marine colonel and US Energy Department official, William Holmberg, thought it might be important and insisted that I spend a week in Flynt going through the archives. Holmberg was absolutely right. Most of what we
historians now know about the context of the development of leaded gasoline has come from those archives — despite
a rather large collection of historical information still (as of December, 2013) being withheld by industry. (Specifically, the successors to the Ethyl Corp., such as Afton Chemical and New Market Inc.) ...
... I was aware, for instance, that Ethyl critics had been attacked in past decades, notably Clair Patterson of Cal Tech and Herbert Needleman of the University of Pittsburgh. ...
... Leaving aside the question of whether history is, in itself, a promotional endeavor, or whether historians should or should not “investigate,” or even whether ethanol is or isn’t net energy positive (here, reasonable people differ), the criticism was the
strongest of any that directly came my way. ...
Show me one shred of evidence that the root cause of the brain damage was not lead. Why can't you reproduce their work at home?
What if there was a conspiracy to poison people who smoke marijuana in a way that cause brain damage and blame it on the pot?