Many people think cannabis smoke is harmless – a doctor explains how this belief can put people at risk

Although tobacco use among adults in the US is declining, cannabis use is increasing. Laws and policies regulating tobacco and cannabis use also go in different directions.

Tobacco policies are becoming increasingly restrictive, with smoking bans in public places and sales restrictions, such as nationwide bans on flavored products.

In contrast, more and more states are legalizing cannabis for medicinal or recreational purposes, and there are moves to allow exceptions for cannabis in the no-smoking laws.

These changes mean that more and more people will be exposed to cannabis smoke. But how safe is direct and passive cannabis smoke?

I am a primary care physician and researcher in a state where cannabis is now legal for medical and recreational use.

My colleagues and I were interested in how opinions about the safety of tobacco and cannabis smoke have changed during this era of increased cannabis use and marketing.

More and more states have legalized recreational marijuana use.

In our survey of over 5,000 US adults in 2017, 2020 and 2021, we found that people increasingly believed that exposure to cannabis smoke was safer than tobacco smoke. In 2017, 26% of people thought it was safer to smoke a cannabis joint than a cigarette every day.

In 2021, over 44% chose cannabis as the safer option. Likewise, people were more likely to rate passive smoking of cannabis as “completely safe” compared to tobacco smoke, even for vulnerable groups such as children and pregnant women.

Despite these views, new research raises concerns about the health effects of exposure to cannabis smoke.

Do Cannabis Opinions Agree With Science?

Decades of research and hundreds of studies have linked tobacco smoke to several types of cancer and cardiovascular disease.

However, far fewer studies have been conducted on the long-term effects of cannabis smoke. Because cannabis remains illegal at the federal level, it’s more difficult for scientists to study.

It has been particularly difficult to study health outcomes, which may take a long time and require more effort to develop.

Recent reviews of research on cannabis and cancer or cardiovascular disease found that these studies were inadequate because they included relatively few people with high levels of exposure, didn’t track people long enough, or didn’t properly account for cigarette smoking.

Many proponents point to the lack of clear evidence on the adverse health effects of exposure to cannabis smoke to prove its safety.

However, my colleagues and I agree that this is an example of the famous scientific quote: “Absence of evidence is not evidence of absence.”

Scientists have identified hundreds of chemicals in both cannabis and tobacco smoke that contain many of the same carcinogens and toxins.

Combustion of tobacco and cannabis, whether by smoking or vaping, also releases particles that can be inhaled deep into the lungs and cause tissue damage.

Animal studies of the effects of secondhand smoke from tobacco and cannabis show similar effects on the cardiovascular system.

These include impaired vasodilatation, increased blood pressure and reduced heart function.

Although more research is needed to determine the risk of lung cancer, heart attack, and stroke from cannabis smoke, what is already known has raised concerns among health authorities.

Why do cannabis opinions matter?

How people perceive the safety of cannabis has important implications for its use and public policy.

Researchers know from studying cannabis and other substances that people who think something is less risky are more likely to use it.

Opinions about cannabis safety will also influence medical and recreational cannabis laws and other policies, such as whether cannabis smoke is treated like tobacco smoke or whether exceptions are made to smoke-free air laws.

Part of the complexity in making cannabis use decisions is that, unlike tobacco, clinical studies have shown that cannabis can have benefits in certain situations.

These include treating certain types of chronic pain, reducing nausea and vomiting associated with chemotherapy, and increasing appetite and weight gain in HIV/AIDS patients. Remarkably, many of these studies were not based on smoked or vaped cannabis.

Unfortunately, although Googling cannabis yields thousands of hits about the health benefits of cannabis, many of these claims are not supported by scientific research.

I encourage people who want to learn more about the potential benefits and risks of cannabis to speak to healthcare providers or seek sources that offer an unbiased view of the scientific evidence.

The National Center for Complementary and Integrative Health has a good overview of studies using cannabis to treat various conditions, as well as information about possible risks.

Written by Beth Cohen. The conversation.

If you are interested in cannabis, please read the studies you need to know about cannabis and heart attack, and CBD from cannabis can help prevent COVID-19 infection.

For more information on cannabis, see recent studies demonstrating that medicinal cannabis can help alleviate depression and the results showing that this compound in cannabis can protect the aging brain and treat Alzheimer’s.

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