marijuana or tobacco
CAPTION: On the brink of regulation in Mexico, we explain the harmful effects of marijuana use. (Photo: iStock)

Who’s faster, Michael Phelps or Usain Bolt? They’re both very fast, but it depends on where. The first is fast in a pool and the second on a track.

With this analogy, Sebastián Rodríguez Llamazares, Professor of Respiratory Pathologies at Tecnológico de Monterrey’s Mexico City campus, illustrates in an interview for Tec Review that it’s not true that tobacco is more harmful than marijuana or vice versa, it all depends on the conditions of consumption.

“In the lungs, the effect of tobacco is worse than that of marijuana. This fact leads to the misconception that marijuana does less harm than tobacco.”

“But the effect of marijuana on the neurological system is much greater than that of tobacco. Long-term use of marijuana causes cognitive impairment, while smoking tobacco doesn’t,” explains this expert, who’s also a physician attached to the Department of Smoking and COPD (chronic obstructive pulmonary disease) at the National Institute of Respiratory Diseases (INER).

Rodríguez Llamazares mentions that in order for a person to be classified as a patient at risk of developing COPD, they’d have to have smoked a pack of 20 cigarettes a day for 10 years. However, marijuana is not normally consumed in those quantities.

“This is why the pulmonary effect of marijuana is less noticeable, although it can’t yet be said to be less harmful. Smoking marijuana also produces smoke containing carbon and therefore damages the lungs,” he explains.

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Chronic consumers

According to this Tec professor, there’s evidence that some chronic marijuana users do develop COPD, although it’s not the norm; they’re isolated cases.

It’s known that practically 100% of laryngeal cancers, 80% of bladder cancers, and 90% of tongue cancers are associated with tobacco. What’s more, smoking tobacco increases cardiovascular risk, so the possibility of a heart attack is four times greater than in those who don’t smoke.

The advantage of studying the health effects of tobacco is that it’s very easy to measure its consumption; it’s enough to know how many cigarettes a person smokes a day.

To be able to say that marijuana causes cancer, the substance’s effect on people would have to be studied. Then they would have to be compared with people of the same sex, age, and race who don’t smoke marijuana and see how many got cancer. Finally, both groups would have to be compared.

“People may say that they smoke one joint a day, but there are different sized joints.  So, it’s difficult to objectively determine how much marijuana a person consumes on a daily basis. Making the causal association (between marijuana consumption and cancer) is scientifically very complicated. This has led to the message that marijuana isn’t harmful, which is a lie,” explains Rodríguez.

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The case of passive smokers

This INER physician has the following to say regarding those who don’t consume either of these substances but inhale the smoke of those who do:

“We know that exhaled smoke is more toxic than the air inhaled when smoking. The problem is that exhaled smoke is diluted in the surrounding air, so its level of toxicity decreases compared to that of inhaled smoke. When somebody breathes in second-hand smoke, we don’t know exactly how much. So, it’s very difficult to measure the effect of smoke on a passive smoker.”

Although passive smoking is known to be harmful to some extent, the exact damage hasn’t been confirmed. The same lack of definition occurs in the case of marijuana.

Effects on the mind

Nicotine, a component of tobacco, is extremely addictive, and marijuana doesn’t contain such an addictive substance. However, “it’s false that marijuana doesn’t cause addiction,” says Rodríguez.

What’s more, the mechanism through which marijuana acts on the body causes neuronal connections to break down little by little. This doesn’t happen with tobacco.

According to Lorena Reyes Santos, a psychiatrist at the Neurodigital Human Project, both substances are similar in that they’re usually smoked, but neurobiologically they’re completely different.

“Tobacco acts upon nicotinic receptors that have to do with specific processes in the brain. Marijuana, on the other hand, acts upon endocannabinoid receptors connected to a completely different neuronal system, and evidently causes other types of effects,” she says in an interview for Tec Review.

According to this mental health expert, tobacco helps people who consume it regularly with concentration and having better cognitive performance. This isn’t the case for people who don’t consume it, who can even become very anxious because of it, since they’re not used to a dose of nicotine.

“For people who are vulnerable, who have a neurodevelopmental disorder or a genetic predisposition to psychosis or schizophrenia, smoking marijuana can trigger symptoms. This can happen from the very first dose; regular consumption isn’t even necessary,” warns Reyes Santos.

Those who don’t have this type of predisposition don’t usually have a major problem, since marijuana just relaxes them and gets rid of anxiety symptoms. “But there are also other vulnerable people who can exhibit symptoms of severe anxiety and can suffer from paranoid thoughts during marijuana intoxication.”

Marijuana does cause some alterations in brain function to heavy or chronic users.

“The cognitive processes begin to slow down, working memory becomes impaired, and this leads to amotivational syndrome, which causes consumers to become lethargic, they can no longer do their activities, they no longer find meaning in things. They don’t respond strongly to pleasant or unpleasant stimuli,” says the psychiatrist.

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Rodríguez and Reyes agree that tobacco is in the lead in terms of being studied compared with marijuana. So, there’s still not enough information to say that marijuana isn’t as harmful.

Rodríguez makes the following reflection regarding the underlying causes of the recent trend to defend the “recreational” use of marijuana:

“We must change the impression that smoking marijuana isn’t as bad as smoking tobacco. This has to do with an idea that’s been developing over the last few years based on free-market interests, because 80% of the shares in companies that sell marijuana belong to the tobacco companies.”