As Washington and Colorado move ahead on the rules for legalizing marijuana, it's opening a new debate on pot safety.
Is pot really healthier than alcohol and cigarettes - or just as dangerous?
Pot smoking it turns out, creates the same toxic substances that tobacco does, and ounce for ounce actually leaves more tar in your lungs than cigarettes do. And that comes from a researcher often quoted by marijuana supporters, Dr. Donald Taskin, who disclosed his findings seven years ago.
"What we found was about four times as much tar, which contained carcinogens, and four times as much was deposited in the lung," says Taskin.
It's why pot users cough the way smokers do even though they smoke less.
Yet despite this, Dr. Taskin says surveys of cancer patients find no increased cancer risk from heavy pot smoking.
"We failed to find any positive association between marijuana, even heavy marijuana use."
But what that also means is there is no decreased risk of cancer either. Whatever the cancer prevention effect of marijuana's key ingredients, they're negated by the toxic stuff created when you burn it.
The other thing to consider is that just as alcohol messes up the lives of alcoholics, a study published in Britain in 2007 found the hallucinating effects of heavy marijuana use can mess up people predisposed to schizophrenia, especially teenagers.
Bottom line - marijuana can't kill you the way alcohol and cigarettes can. But it can mess with your mind - and while its beneficial effects are real, they do not come from smoking it. They come in spite of smoking it.