Lets see what science says:
Short term effect:
altered senses (for example, seeing brighter colors)
altered sense of time
changes in mood
impaired body movement
difficulty with thinking and problem-solving
impaired memory
hallucinations (when taken in high doses)
delusions (when taken in high doses)
psychosis (when taken in high doses)
Long term effects:
When people begin using marijuana as teenagers, the drug may impair thinking, memory, and learning functions and affect how the brain builds connections between the areas necessary for these functions.
temporary hallucinations
temporary paranoia
worsening symptoms in patients with schizophrenia—a severe mental disorder with symptoms such as hallucinations, paranoia, and disorganized thinking
Physical effects:
Breathing problems.
Increased heart rate.
Problems with child development during and after pregnancy.
This does not include the list of now edible's and the growing concentration of THC that is being used in it now.
So medical science disagree's with the it's safe crowd.
Right off the top of my head I know that most of this is BS or is based on a long-shot side effect with incredibly low incidence rate. A few examples.
"breathing problems"? LOL. There was one study that indicated a very slight increase in chance of developing emphyzema, yes, but that had to do with chronic (very) heavy users. The vast majority aren't.
"Increased heart rate": slightly, temporary, only in some users, and not in any way life-threatening unless you happen to be a 400 pounder with severe hypertension.....
Hallucinations and paranoia as a long-term effect? lol, nope.
Shizophrenia: dishonest tunnel vision there. Just about any recreational substance can trigger latent schizophrenia, but that schizophrenia would manifest anyway. That's absolutely not a reason to oppose marijuana in any sense.
Delusions, hallucinations, psychosis in "high doses"? I can only imagine that - assuming you didn't make it up - this is some incredibly low incidence in self-reported populations by people who never used it before, then ate an entire tray of brownies or something.
But really, you're just trying to scare-monger with a list of potential effects that simply do not manifest in moderate users.....just like cirrohsis does not manifest in moderate alcohol users.... just like liver failure does not manifest in responsible consumers of Tylenol....just like responsible consumers of naproxen sodium or ibuprofen do not end up burning a hole in their stomach. I'm guessing that's why there aren't any links to the studies themselves, assuming your statements are even coming from studies.
If you think your unsourced list is a reason to oppose something, try looking up the FDA's full lists of potential side effects of over the counter drugs. You can find all sorts of potentially severe reactions listed. But, of course, they virtually never happen and/or only happen with misuse of the product.
:shrug: