Yeah sure, I just had been a little busy, but there is plenty of evidence for this.
HOWEVER, before I do, I want to add that there is more than enough medical studies on the health damages from Marijuana that are readily available with one easy search on google, that it seems that a ask for evidence is not genuine. When you ask for evidence that takes you five seconds to find for yourself, it becomes pretty clear that it's not a matter of not being able to find the studies, it is an issue of not wanting to address or be honest about them.
That is a major problem if you want the average public to take the legalization effort seriously. There are very clear real life problems that occur from the use of Marijuana, but the societal, safety health, and financial damage from having the drug being declared as illegal is far worse. However, if you try to feed the American public a flat out lie of weed causing no harm whatsoever, you will never get the public to move past the bull of that argument to the argument of the larger damage being done by the drug war.
Starting out an argument for a flat out lie will not serve the effort for legalization at all. Triterope is not unique in his personal experiences of marijuana users of "disinterest in economic activity; incomplete education; underemployment; financial dependence on the government or family members; strained relationships." You are not going to get anywhere by asking for evidence of his personal experiences. You have to take his concerns, and similar concerns from other Americans seriously, and reasonably outline how both their lives and the lives who they know of who use Marijuana would be better off by legalization.
Now, as for some of the many examples of health affects from Marijauana:
Brain Pollution and the Real Reason You Shouldn’t Use Drugs
Long-Term Marijuana Use Affects Memory
Adolescent Marijuana Use May Cause Lasting Cognitive Deficits
Marijuana Use Affects Blood Flow in Brain Even After Abstinence
Marijuana and Teenagers: Does Drug Use Cause a Bad Brain?
Marijuana use linked to increased risk of testicular cancer
etc, etc, etc,
Where is the evidence for this?