The Smoke That Satisfies, Terrifies
Marijuana: Neither harmless nor tragically toxic

By Gilien Silsby, USC News

It is the world’s most commonly used illicit drug, and perhaps the most controversial of all substances. Marijuana has been at the center of debate for decades, with equal numbers calling for its legalization and ban.

In his new book, “Understanding Marijuana” (Oxford University Press, 2002), Mitch Earleywine, an associate professor of psychology at USC College, attempts to sort out myths and facts about the drug. After analyzing some 500 studies, Earleywine’s ultimate conclusion is mixed—marijuana is neither completely harmless nor tragically toxic.

“The common human desire is to split the world into two categories,” says Earleywine, an expert on substance abuse and personality. “Decisions are easier when everything is black or white. Yet the world remains in glorious color.”

Earleywine looks at the history of medical and recreational marijuana use, cannabis pharmacology, health effects and treatment. After examining studies dating from 1681 to 2001, Earleywine has arrived at a number of conclusions, including:

Daily marijuana use alters brain function. About 10 percent of regular users develop troubles ranging from memory lapses and paranoia to an increased tolerance to the drug. Marijuana does not spur aggressive behavior or impede motivation.

Marijuana is not a gateway drug and is less harmful than tobacco and alcohol. Less than 1 percent of marijuana users try heroin.

While marijuana does help glaucoma, it is not as effective as recently developed Canasol eye drops, which do not cause any intoxication and last much longer.

Users cannot learn new material while they are high on marijuana. Studies show an impairment in “free recall” memory and find that users are unable to separate relevant from irrelevant stimuli.

Unlike alcohol or aspirin, marijuana has never been known to cause a lethal overdose. Earleywine cautions that an incomplete reading of research can support any argument for or against marijuana. After examining the studies, he found that some researchers ignored crucial information and data in their final analyses.

For example, he says, studies slanted against marijuana legalization mention that tetrahydrocannabinol (THC), the main active chemical in marijuana, often appears in the blood of people involved in auto accidents. But the studies fail to mention that most of these people also had high blood-alcohol levels.

Similarly, studies slanted in favor of marijuana legalization cite a large study that showed no sign of memory problems in chronic marijuana smokers. However, they neglect to mention that the tests were so easy that even a young child could perform them.