WEEDING OUT THE MYTHS:

IS MARIJUANA SAFE?

Yet an estimated 20 million Americans smoke it regularly-over three times more than use of cocaine.

Because smoking pot is so widespread, popular myths have sprung up about it. Many think marijuana is a harmless "recreational" drug. The experts disagree. If you're thinking about smoking it, check the facts, not the myths, and think again.

Myth: Smoking marijuana is safer than smoking cigarettes.

Fact: Actually, smoking one marijuana cigarette may be as harmful to your health as five tobacco cigarettes, according to a study by the University of California at Los Angeles. Smoking pot leaves five times as much carbon monoxide increases the risk of heart disease, and tar has been tied to higher cancer risk.

The dangers are heightened by the way marijuana is usually smoked-deeply inhaled and held in the lungs. This causes you to breathe in 36 percent more smoke per puff than you do from a tobacco cigarette, the study said. And you hold post smoke in your lungs about four times longer, increasing the amount of exposure to possible carcinogens.

Secondhand smoke is also a hazard. In a national Institute on Drug Abuse study, five men were exposed to marijuana smoke in an unventilated room. Despite not taking a single puff themselves, they reported feeling high and the traces of the drug were detected in their systems up to five days later.

Myth: Marijuana is not addictive.

Fact: Your body builds up a tolerance to marijuana, which means that it takes more and more of the drug to get high.

These days, even if you're a new user, you're starting big-pot today is far more potent than it was 10 years ago. Smoking one marijuana cigarette today is about the same as smoking seven then, says a University of Mississippi study. A White House drug abuse official has likened that to drinking a beer vs. a whole fifth of 100-proof rum.

You can also become psychologically dependent on pot, unable to function confidently without using it. Regular users can come to rely on the drug when stressed, bored, frightened or anxious, or when socializing. Sometimes they experience mild withdrawal symptoms, such as nausea, irritability or insomnia, when not smoking post.

Myth: Marijuana doesn't lead to further drug use.

Fact: There's no getting around it-pot users often experiment with other dangerous drugs, like cocaine. For adolescents especially, marijuana has been called a "gateway" drug, predisposing them to further drug use.

A 1984 Gallup poll revealed that 93 percent of those who had tried cocaine used marijuana first, and that 84 percent of adolescents using cocaine were also using marijuana. Also, 74 percent of adults who had used pot 100 times had also tried cocaine.

Myth: Other than a little smoke, marijuana is harmless.

Fact: As research continues, evidence of the dangers of marijuana piles up.

• Pot disrupts learning and memory functions in the brain, causing short-term memory loss and problems concentrating. It also upsets the balance of brain chemicals controlling mood, appetite and energy.
• Pregnant women who smoke marijuana increase the danger of problems in their babies' development, and raise miscarriage and stillbirth risks. In men, sperm production is slowed, resulting in fewer, less-healthy sperm cells.
• Current studies show that marijuana use may even weaken the immune system, lowering one's ability to fight disease and infection.
• Motor skills are impaired to the point where a driver high on pot is just as dangerous as a drunk driver.
• Heart rate can jump 50 percent, increasing blood pressure, which can be a great strain on users with high blood pressure or heart problems.