The British rag The Daily Mail has been coming up in Google News with the above linked story.
It is incredibly faulty; it's propaganda. The headline screams "The terrible truth about cannabis: Expert's devastating 20-year study finally demolishes claims that smoking pot is harmless".
In the first place, no drug is harmless. Few things in existence are completely harmless, in fact. Even something necessary for life, like water, can be dangerous. Unlike marijuana, you can actually overdose on water. People have died from drinking too much water, nobody has died from smoking too much pot.
"Is pot harmless?" is not only the wrong question, it's a stupid question. So lets look at this fellow's "20 year study" and at the fellow's credentials.
Is he a neuroscientist? Biochemist? Physician?
No. Wikipedia says that Wayne Denis Hall a psychologist. As such, he's no more qualified to study the dangers of drugs than I am. Lets look at the claims, with the most stupid first, that the Mail repeats..
"If cannabis is not addictive then neither is heroin or alcohol."
This is just not incorrect, it's WRONG and irresponsible. Apparently Professor Hall has never seen an alcoholic going through withdrawal, but I have. It's horrible; the addict goes through not just psychological terror, seeing snakes and spiders on them, it is physically painful and can cause seizures. Withdrawal from heroin or alcohol can be fatal.
Marijuana's "addiction" is psychological only; unlike heroin, alcohol, or coffee, there are no physical withdrawal effects. Marijuana is more like orange juice than alcohol. Get drunk every day for a year and quit and you could die.
Get stoned while drinking orange juice every night, and when it's gone quitting both will be similar, although you'll miss pot more.
If pot is as addictive as heroin, why don't potheads steal to support their habits, like almost all heroin addicts do?
The world has too many drug addicts as it is, and statements like these from a scientist will lead people to believe that heroin and cocaine are as harmless as marijuana.
One in six teenagers who regularly smoke the drug become dependent on it
That's likely true. Marijuana is, in fact, dangerous to teens. It has been shown to interrupt the development of the adolescent brain. Kids shouldn't smoke pot, but unfortunately it's easier for a teenager to get pot than it is for an adult. And every pot smoker I know who started as a kid is in poverty. Kids, stay away from it until you're 19 or preferably older.
We can dismiss adolescent pot use, it is obviously harmful.
Cannabis doubles the risk of developing psychotic disorders, including schizophrenia
Yes, there is a correlation between mental illness and all psychoactive drugs, but the causation goes the other way. There were schizophrenic kids in my neighborhood when I grew up, all were obviously batshit insane, and all wound up on drugs later.
One in ten adults who regularly smoke the drug become dependent on it and those who use it are more likely to go on to use harder drugs
Again, the "dependance" is little worse than orange juice and nowhere near as bad as coffee. As to leading to harder drugs, this is the fault of prohibition. "Got any weed, man?"
"No, I'm out. Want some coke?"
This problem goes away with legalization, as Colorado has shown.
Driving after smoking cannabis doubles the risk of a car crash, a risk which increases substantially if the driver has also had a drink
Well, duh. I grin at the "increases substantially if the driver has also had a drink".
I'll also note that unlike drinking, when you're high you don't WANT to drive a car. You're far less likely to get behind the wheel after a couple of joints than after a couple of shots of whiskey.
He also states that taking the drug while pregnant can reduce the weight of a baby, and long-term use raises the risk of cancer, bronchitis and heart attack.
Smoking anything does increase the danger of various lung diseases, but a study a few years ago baffled the researchers who did the study; the results were the opposite of what they expected. They studied four groups of geezers -- long term pot smokers, cigarette smokers, people who smoked both and nonsmokers.
They expected twice the cancers in pot smokers than nonsmokers and twice the cancers in smokers of both than cigarettes alone. However, the data showed that pot smokers actually had fewer cancers than nonsmokers (although statistically insignificant) and smokers of both had half the cancers than those who only smoked cigarettes.
Rather than causing cancer, pot may actually prevent it.
This sort of sensationalist bullshit is why so many people distrust science. This fellow is a psychologist who mostly studies adolescents. Yes, kids and pregnant women shouldn't smoke pot, or anything else. But we should legalize it for adults, partly to keep it out of kids' hands.
