Sometimes even with scientific studies it is difficult to estimate to what extent they are 100% correct. In November, for example, a study was published that would show that smoking weed is even worse for your health than puffing cigarettes. But now a new study has been published that does not link smoking weed – purely that is – with reduced lung function in young adults.
Blowers and/or tobacco smokers followed for a long time
Let’s go back to November, when CNNBS reported on a Canadian study claiming that smoking tobacco is slightly less bad for the lungs than weed. The scientists based themselves on CT scans of the lungs of 150 people, which would show that, among other things, pulmonary emphysema is more common among cannabis consumers than among cigarette junkies. Not much difference (75% to 70%), but still… Only 5% of the non-smokers/blowers suffered from this lung disorder.
READ ALSO: Study: Smoking weed is even worse for the lungs than cigarettes
Now there is another fresh study on the table that suggests that there is little alarming going on with the lungs of (pure) weed smokers. Under the title ‘Do tobacco and cannabis use and co-use predict lung function: A longitudinal study’, the study was published at the end of January in the journal Respiratory Medicine.
A longitudinal study is a study in which the participants are tested more often over a longer period of time. The researchers in this study found that smoking cannabis alone was not associated with reduced airflow or reduced lung function.
More understanding about the harmfulness of long-term cannabis use
The new study, from researchers at the University of Queensland in Australia, examined whether habitual cannabis smoking is associated with harmful effects on the lungs of young adults in particular.
“Cannabis use is becoming increasingly legalized and consumption is becoming more commonplace,” said lead author Professor Jake Najman. “In this context, it is important to understand more about the harmfulness of long-term cannabis use.”
To investigate, the researchers followed a group of 1,173 young adults from ages 21 to 30, testing their lung function using a spirometry assessment at the beginning and end of the 9-year period.
[Spirometrietests worden gewoonlijk gebruikt om longaandoeningen, zoals astma en COPD, te helpen diagnosticeren door de hoeveelheid lucht te meten die iemand in één geforceerde ademhaling kan uitademen. Dit gebeurt met een apparaat dat een spirometer wordt genoemd en dat een mondstuk heeft waarin de patiënt kan ademen.]
Worse lungs due to smoking only tobacco and tobacco joints
The researchers also checked whether the participants smoked cannabis, tobacco, both, or nothing over the nine years. This was done using questionnaires at ages 21 and 30, when lung function tests were performed. Then the researchers analyzed the data to see if smoking cannabis over 9 years had reduced lung function.
The results showed the expected association between tobacco smokers and reduced airflow. Those who only smoked cigarettes, or cigarettes with cannabis, had reduced airflow over the 9-year period.
Cannabis did not contribute to these reductions, in addition to what was already found in smokers who only smoked tobacco. But perhaps surprisingly, in light of the recent findings on cannabis and emphysema, smoking cannabis alone did not reduce airflow and did not appear to affect lung function. Even after 9 years of use, cannabis smoke exposure did not seem to affect the lungs!
Smoking weed with tobacco does not seem to pose an EXTRA risk
The authors conclude that “cannabis appears to be unrelated to lung function, even after years of use.” They also concluded that the use of cannabis in combination with tobacco does not appear to pose an additional risk to the lungs beyond the damage already associated with tobacco smoking.
So this is in stark contrast to the recent study in the journal Radiology, showing that smoking cannabis is more likely to cause emphysema than tobacco. In that study, CT scans of the chest showed higher levels of emphysema in smokers who used both cannabis and tobacco than those who used tobacco alone.
It’s important to note, however, that Radiology’s research was limited by the fact that it didn’t look at cannabis-only smokers. Thus, the results suggesting higher rates of emphysema should be seen as relevant to the use of cannabis and tobacco together – not necessarily cannabis alone.
There may be combined effects of mixing these two substances that are not present with either alone. This doesn’t mean we can rule out cannabis as a possible cause of emphysema, but it does mean we need more research to confirm that these results apply to people who only use cannabis.
What scientific research should we believe now?
The study of Respiratory Medicine in contrast, only studied pot smokers and found no differences in lung function with the non-smoking control group. The study in Radiology also used a relatively small sample of only 146 patients, compared to the 1,173 respondents in the study who found no effects on lung function from cannabis smoking.
Still, it is important to point out some other differences between these two studies that may partly explain the seemingly contradictory results.
- First, the study in Radiology mostly involved older people, who have had more time to damage their lungs. It is quite possible that cannabis users would show more noticeable harm after more years of smoking than the 9 years studied here. This study does not rule that out, it just shows no evidence of damage in the first 9 years.
- It is also important to note that the study in Radiology CT-scans used to diagnose lung problems, while the recent study in Respiratory Medicine spirometrie used. Different tests can produce different results. In fact, some researchers suggest that spirometry tests in particular may miss conditions like emphysema at an early stage. So the damage done by this test may go unnoticed – as with the CT scan.
Conclusion: more research is needed
Given these research limitations, it remains to be seen whether smoking cannabis can lead to lung problems and harm as tobacco more clearly does. We need more studies on the effects of smoking cannabis alone – over a person’s lifetime – before we can really come to a strong scientific conclusion.
[openingsbeeld: Kazyaka Konrad/Shutterstock]