In the 1950s, marijuana was known as the killer weed. Reefer madness. The steppingstone to heroin.
A decade later, many researchers decided the early warnings were overblown and slightly hysterical, contending that marijuana smoking was no more harmful than the occasional cocktail.
Today, the pendulum is swinging back, as recent research has turned up increasing evidence of health hazards associated with chronic marijuana smoking.
Adding to the concern is the sharply increased potency of the marijuana now in use in the United States. Some of the studies done in the past are now obsolete because the drug is so much stronger now. Even recent studies have been conducted with marijuana that is less potent than what is being sold today on the streets.
Today, as a result of sophisticated growing techniques, the average content of tetrahydrocannabinol, or THC, the active ingredient in marijuana, in top-grade sinsemilla (seedless) marijuana is about 7%, and some potent strains can be as high as 14%, according to Dr. Sidney Cohen, a professor of psychiatry at the UCLA Medical School and one of the nation's early marijuana researchers.
In contrast, only 10 years ago, the average THC content in marijuana bought on the street was 0.5% to 1%, Cohen said. And the THC content in marijuana used in clinical tests in the 1970s was 1% to 2%, he added.
'Ten Times Stronger'
"A lot of the stuff on the streets is now more than 10 times stronger than what people had been used to; it's almost a completely different drug," said Cohen, a drug consultant for the U.S. State Department. "But I've never seen any human studies that used 4% or 5% THC. . . . We may have to redo a lot of research. But even research with the lower-potency marijuana has indicated some real health problems."
Cohen in recent months surveyed marijuana research conducted during the past few years and wrote a paper for a congressional report on drug abuse. The following are some of his findings:
-THC causes changes in the reproductive systems of test animals.
-Marijuana smoking among pregnant women can adversely affect fetal development.
-Extensive lung damage has been documented in chronic marijuana smokers.
-THC has impaired the immune system in test animals and decreased resistance to infections.
-The already critical problem of drunken driving is exacerbated by marijuana smoking.
While little research has been conducted using marijuana with extremely high THC contents, drug clinics are beginning to see the effects.
Darryl Inaba, a director at the Haight-Ashbury Drug Clinic in San Francisco, said since the potent California marijuana became prevalent in the early 1980s, he has begun treating patients suffering from "acute anxiety reactions." At first those at the clinic assumed the marijuana was laced with PCP, Inaba said, but after testing they determined it was just high-grade pot. The patients who smoke too much strong marijuana too fast, he said, "require talk-down treatment, just like we treat a bad LSD trip."
Ten years ago people would have laughed at the idea that marijuana could cause such an adverse reaction or that users would have a difficult time giving up smoking. But now, he said, several patients a month check into the detoxification clinic because they cannot quit smoking the potent pot.
"When I was in college in the 1960s there was a lot of phony-baloney research about marijuana that was easy to poke holes in," said Ned Walsh, administrator of alcohol and drug programs in Mendocino County. "It's really unfortunate, because then people tended to dismiss anything negative about pot. But now we're finding out things that can't be ignored."
There currently are 22 million marijuana smokers in the country, according to the National Institute for Drug Abuse, and the number has stayed about the same for the last few years.
There still are many questions that remain unanswered about marijuana, and some researchers are not convinced that marijuana leads to all the health problems that have been reported.
Effects More Subtle
They are reluctant to draw conclusions between animal studies and the effect on humans; more human studies, they say, are needed. But because the effects of marijuana smoking are more subtle than other drugs, research can take years before it is conclusive.
And marijuana researchers often do not receive as much funding as those studying hard drugs. Despite the Reagan Administration's pronouncements about the problems of drug use, research funding has not kept up with the inflation rate, Cohen said.
Kevin Zeese, director of the National Organization for the Reform of Marijuana Laws (which has been fighting for legalization of marijuana since 1970), acknowledges that chronic smoking causes some health problems. But, he said, of the 22 million Americans who are at least monthly users of marijuana, only about 5% are daily smokers. And there is no evidence, he said, that smoking in moderation is harmful.