Marijuana and health.

Of all the illicit drugs available in this country, marijuana is by far the most widely used and the most controversial. During the late '60s and early 70s, "pot" was the symbol of the drug counterculture, but its use has increased so much recently, particularly among middle-class adolescents and young adults, that smoking marijuana has become almost a social norm. By 1979 more than 50 million Americans had tried it at least once. In 1981, 7 per cent of the high-school seniors surveyed said that they used it daily, and 46 per cent said they had used it at least . . .