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Seattle Times coverage of pot policy, culture and lifestyle.

June 27, 2014 at 3:55 PM

What are the potential harms of marijuana?

President Reagan once said he had proof that smoking one joint is “equal in brain damage to being on Bikini Island during an H-bomb blast.” President Obama, a prodigious toker in high school and graduate of Harvard Law School, offers strong evidence to the contrary.

Leading cancer researcher Dr. Jerome Groopman has noted that debates about marijuana tend toward the subjective, with players viewing data like Rorschach blots.

Even when credible studies appear to reach important findings, other studies undercut their conclusions. Look no further than the crucial issue of how marijuana impacts the developing brain. The so-called Dunedin study, well-known in pot-policy circles, found heavy use in adolescence was associated with stunted IQ. A new study from Norway, using the same data, said factors other than marijuana, such as socio-economics, were to blame.

Roger Roffman spent his career as a marijuana researcher and dependence counselor. A University of Washington professor emeritus and former pot-smoker, Roffman believes many people can use pot without harm. But experience has shown him that others can be hurt by it. To get beyond hyperbole and scare tactics, Roffman points to a brochure produced by the University of Washington Alcohol and Drug Abuse Institute as a model for accurately conveying the risks of marijuana. Many of the answers below are informed by the Institute’s brochure.

What are the risks for occasional adult consumers?

Here’s what the UW Alcohol and Drug Abuse Institute (ADAI) says: “Adults who don’t have heart disease or psychiatric conditions, don’t get high during pregnancy or when it’s dangerous, and use pot occasionally probably aren’t at risk of any harm to their health.”

But some infrequent users, such as New York Times columnist Maureen Dowd, say they felt horrible after consuming pot-infused edibles. What about that?

Dowd felt extremely uncomfortable, but there’s no evidence her health was harmed by eating part of an infused candy bar that contained 16 recommended doses. As the UW Institute advises, first-time marijuana users may experience anxiety or panic; use a small amount at first and wait an hour (two, if consuming edibles) to learn how it affects you.

Anything else I can do to avoid anxiety or panic?

Yes. Under state rules, labels on pot products must show the percentages of two main chemicals in pot: tetrahydrocannabinol, or THC, and cannabidiol, or CBD. THC is the main component associated with feeling “high.” Selective breeding in recent years has increased THC levels while driving down CBD. But CBD is believed to have anti-convulsant and other therapeutic qualities and growers are breeding it back into plants. CBD may also blunt the peak high from THC and have a tendency to reduce anxiety or paranoia. So if you’re really concerned about paranoia, look for pot that has more than 1 percent CBD content. If the high-CBD pot has little or no THC, and you want the feeling of getting high, consider mixing samples of high THC and high CBD strains.

Can I overdose from pot?

There is no known fatal dose of marijuana. If there is such a dose, it would have to be 1,000 times the amount typically consumed, according to the academics who authored “Marijuana Legalization: What Everyone Needs To Know.” The authors note that the Centers for Disease Control and Prevention reported 26 deaths between 1999 and 2007 as mental or behavioral disorders from the use of pot. “The key distinction here is between a poisoning death — a fatal overdose of the drug — and a death caused by intoxicated behavior, or by persistent mental illness triggered by drug use, or by suicide by someone whose life-chances had been badly damaged by substance use disorder,” said Mark Kleiman, a UCLA professor and co-author of the book about legalization.

Citing the case of a young man in Colorado earlier this year who fell to his death after eating a pot-infused cookie, Kleiman said he “surely died from cannabis use, but the cannabis didn’t poison him.” Any intoxicant increases the risks of accidents, Kleiman added. And pot is less risky than alcohol in that regard – as some 7,500 die each year of accidental falls due to being drunk, he said. But the claim that “no one ever died from cannabis” is false, he said.

Still, even if all 26 deaths were related to overdose, and not other factors, Kleiman and his co-authors say the three deaths per year would be equivalent to the risk of dying in a commercial plane crash. There are non-fatal overdoses for sure, as tens of thousands of people end up in hospital emergency rooms every year for reasons related to marijuana use. The vast majority are treated and released without being admitted.

Does pot smoking cause cancer?

Scientists are not certain if pot smoking increases the risk of cancer. Many studies have not found an increased risk, according to the UW ADAI.

Will it damage my lungs?

The latest research suggests that smoking is likely to increase symptoms of chronic bronchitis, such as coughing and wheezing. Scientists also are concerned that the way pot is smoked – by inhaling deeply into lungs and holding smoke there – can lead to tar being deposited in lungs.

Can getting high cause memory problems?

The main psychoactive ingredient in pot, THC, can affect specific sites in the brain, including the hippocampus, which is associated with memory. Scientists think getting high can impede your short-term memory, or ability to remember recently learned information. It does not impact other types of memory, such as the ability to recognize things, or recall a learned skill, such as riding a bike.

What if I’m pregnant?

THC crosses the placental barrier, just as alcohol does. We still don’t know enough to be certain about all the risks. But scientists believe regular marijuana use during pregnancy can lead to babies born with reduced weight. According to the National Institute on Drug Abuse, research suggests that babies born to women who used marijuana during their pregnancies may have subtle neurological alterations and, later in childhood, can show diminished problem-solving skills, memory, and attention. However, the fact that pregnant women who use marijuana may also smoke cigarettes or drink alcohol makes it difficult to determine exactly how much of these effects are attributable specifically to marijuana.

Can pot impact my mental health?

Again, the science is not conclusive. Some people get depressed when high, others psychotic. But scientists aren’t sure if pot causes these problems, or other factors. But there is an important exception, according to the UW Institute. People vulnerable to psychosis, or who have a history of it, face a risk of having a psychotic episode if they get high. For teens, scientists believe, the risks of mental-health problems are greater if they consume pot.

What other risks do teens face?

The chief concern for young people is that their brains are still developing. The pre-frontal cortex, for example, might not develop the way it is supposed to if a teen smokes a lot of pot. That could lead to memory problems, learning difficulties and problem-solving struggles. And these problems could be permanent. Teens who use a lot of pot might also have increased chances of depression or other mental illnesses.

Is pot addictive?

Not for most people, according to the UW Institute. It doesn’t take priority over responsibilities at home, school, work or with friends. For some, though, pot use looks a lot like addiction. They want to cut back or quit, but they don’t follow through. Important things, such as friendships, are sacrificed so they can get high. Some scientists estimate that 9 percent, or 1-in-11 pot smokers, develops the symptoms of addiction. To avoid such problems, the UW Institute advises getting high once a week or less.

Is driving while high dangerous?

Driving high increases the risk of accidents, although not as much as alcohol does. Driving high can cause impairment, such as slower reaction time and divided attention, or distraction. If you must drive,give yourself three or four hours if you’ve inhaled marijuana. If you’ve ingested an edible, the safety margin needs to be hours longer.

Comments | More in Ask Us Anything | Topics: cannabidiol, harms, marijuana

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