As a long time marijuana user I am leaning towards that view and I've ceased using it but largely "permanent" is wrong and its the same thinking that lead to war on drugs.

In large doses, it can bring about negative effects especially in people with ADD but the bad parts are almost always gone after cessation.

I don't think it

It's that when you are in your teens and you start smoking marijuana, the risk is big but I see many grey markets happy to sell you marijuana to people still going to high school.

I find both sides obnoxious, the Singaporeanesque fear mongering about "permanent damages" based on curated and manipulated data and the Western panacea attitude that it be used for everything.

Trying to tie lead exposure to marijuana is just asinine.