Marijuana: Fact and Fiction. (Unit 4: Street Drugs).

Grass, weed, Mary Jane, pot, dope, cannabis, reefer, sinsemilla Even if you've never actually seen marijuana, you've probably heard most of its street names. Marijuana has been featured in so many movies that you may think you know all there is to know about it. But a lot of the popular folklore about marijuana turns out to be untrue.

Here are the facts and fictions.

Fiction: It's safer than cigarettes.

Fact: Marijuana contains many of the harmful chemicals found in tobacco smoke, including some that are known to cause cancer. It contains three to five times as much tar and carbon monoxide as cigarette smoke. It also causes many of the same respiratory problems that cigarettes cause, including chronic hoarseness, coughing, bronchitis, and emphysema It raises blood pressure and heart rate, which can lead to heart disease.

Marijuana smoke can be more harmful than cigarette smoke because it is usually inhaled deeply into the lungs and held there for up to four times as long as cigarette smoke is held. That allows more time for damage to the lungs. Marijuana smoke isn't filtered before it reaches the lungs. And a marijuana cigarette is usually smoked until it is used up, unlike regular cigarettes, which means larger quantities of harmful chemicals reach the lungs.

Fiction: It's safer than alcohol.

Fact: One of marijuana's most noticeable effects is that it changes the user's perception of time and distance. It also affects the ability to make quick decisions. That means it's dangerous to drive while under its influence. In one study of drivers stopped for reckless driving, one-third of them were found to be under the influence of marijuana.