For the record, that diagram is so fucking off key it isn't funny mate. Some of the stuff is right on, but a heap is seriously off. Heroin, Cocaine, Ketamine and Amphetamine are all really misplaced.
Heroin has a huge stigma about it, and yes its addictive, but opiates in general are probably one of the safest drug classes in the world in terms of physical harm. Its the purity and method of consuming the substance that is the biggest factor. If you're a junkie and you're shooting up some H that's cut with baking soda and god knows what else, do you really think that's going to be good for your veins? I'm not endorsing Heroin in any shape or form (nor have i tried it), but people should understand the facts here.
Same with Coke, the stuff isn't good for you, but pure stuff used correctly isn't very bad for you at all, go overboard and you can wave goodbye to your dopamine levels.
Ket, same deal, abuse and you'll get owned.
The only thing that should be right up in the top right hand corner is Meth, because it does have that super addictive quality to it, and unless you're getting jacked on 99.9% pure ice (which you won't, unless you've got a prescription, you're super obese and live in America :/), you will fuck yourself up.
When it all boils down to it mate, drugs are drugs, they're not good for you and that's a fact. Saying that, everyone talks down drugs while having a ciggie or a beer occasionally, they're drugs aren't they? They also kill a hell of a lot more people per year than all illicit drugs combined times 10. And hey, 400,000+ die every year due to obesity, should KFC become illegal?
Its your body, you should put whatever the fuck you want in it, research whatever you want to do, live a healthy lifestyle and never let anything become a 'haven' for you if your stressed, that includes bud. My view is that we live life once, so find that balance between work and play, go out and get fucked up with your mates. I know I'd rather end up living in an alright house, with a wife and kids, going out occasionally with mates than studying my head off and working a highly paid, high hour job.
S'all bout the balance. I really went off topic... Annnd, i know too much about drugs.
Weed cannot cause cancer or emphysema, THC (chemical that makes you 'stoned') is an anti-carcinogenic. It does however contain a higher amount of tar than cigarettes, saying that, you only need to smoke one 'breath' of cannabis to get high, while people will smoke numerous cigarettes throughout the day, so in reality you're most likely going to put less tar on your lungs anyway. If you're worried about the tar, look into vaporizers, they don't harm you physically at all. It is not physically addictive, but i find it mentally habit forming if I've got bud lying around and nothing to do. You cannot die from bud, you'd have to smoke your body weight in 15 minutes, after the 4th cone you'd pass out anyway. Getting a mental illness from grass is seriously unlikely (<3% or something minute), and even then it is disputed whether cannabis causes an illness, or simply triggers a dormant mental illness that was going to emerge sooner or later. 85% of the Australian population have smoked weed, the government claims (in one of those stupid pot pamphlets) that something like 15% of people who smoke cannabis will be diagnosed with a mental illness. So according to them, a huge portion of the Australian population should have a mental illness, do we? No.
k, procrastinating rant over. Back to Xerxes :/