I heard that you can Overdose on THC. I don't know if it's true or not but I've been told scientists injected a rat with a little over 2 times its body weight before it killed it (again, just what i've heard, personally dont stand behind it at all). Even if this is true... realistically you will never be able to get a hold of that much pure THC, not to mention no one is dumb enough to inject it into themselves. You'd die from suffocation before you die from the THC itself.