Whenever a plant-based product is burning, toxins and carcinogens can be released.  Smoking tobacco cigarettes, smoking cannabis, or sitting near a wood-fueled campfire will all lead to exposure to these substances, resulting in compromised cardiovascular function and other negative health outcome.

The biggest concern for many patients though is if cannabis smoke, like tobacco smoke, causes an increased risk of lung cancer. The short answer to this question? Cannabis smoke most likely does not lead to an increased risk of lung cancer, but we can’t say that with 100% certainty.

Why don’t we have a definitive answer?

Due to marijuana’s Schedule I status by the federal government, it has been difficult for scientists to research this subject. If marijuana were to be entirely removed, or at least ranked lower, on the list, it would be much easier to conduct the large-scale, high-quality studies needed to fully assess its health impacts. Even with this obstacle, we do know quite a bit about marijuana’s impact on pulmonary health.

What does the research say?

Hundreds of studies have shown that tobacco smoke inhalation is strongly linked with increased risk of lung and other cancers. When it comes to cannabis, there are many fewer studies examining these links, which prevents us from drawing definitive conclusions about cannabis smoke and cancer risk. However, the evidence we have so far suggests that the risk of lung-related negative health outcomes is far lower for cannabis smoke as compared to tobacco smoke. This lower risk may be explained by other differences in the composition of cannabis and tobacco smoke.

How do cannabis smoke and tobacco smoke differ?

Cannabis smoke is different from tobacco smoke in that some of its constituents, like the plant cannabinoids THC and CBD, are non-carcinogenic and demonstrate anti-cancer and antioxidant properties. This may explain why several studies have shown no significant link between cannabis smoke and respiratory cancer (at least for light to moderate cannabis smokers). However, there is mixed evidence on cancer risks for heavy, long-term smokers. A few studies have reported an association between cannabis use and upper airway or lung cancer, but these have come from small case-control studies that suffered from methodological flaws, such as not controlling for tobacco use. More large-scale studies with rigorous methodologies are needed.

Fast Facts about Marijuana Smoke

A broad survey of the scientific literature leaves us with the following list of conclusions about the health effects associated with smoking cannabis:

• Overall, the negative effects of smoking cannabis on lung health appear to be lower than for tobacco smoking.

• Cannabis smoking is associated with lung function abnormalities, but the pattern of these abnormalities is different from those associated with tobacco smoking.

• Regular cannabis smoking can cause physical airway damage, and is associated with the symptoms of bronchitis.

• Secondhand cannabis smoke exposure leads to impairments in cardiovascular function.

• There is no compelling evidence that cannabis smoking leads to obstructive airway disease of emphysema.

• A limited number of high-quality studies have failed to find a link between cannabis smoking and lung or upper airway cancers for occasional or moderate consumers.

• There is mixed evidence for increased cancer risk in heavy, long-term cannabis smokers.

• More research, especially on whether smoking cannabis can lead to lung or other cancers, is desperately needed.

• Alternative methods of cannabis consumption, such as vaporization, do not carry many of the risks associated with smoke inhalation.

Learn more here about getting your medical marijuana card!