Does Marijuana Cause Lung Cancer?
Marijuana, both for recreational and medical use, is becoming legal in more states. Even as more people use it, health experts aren't sure whether smoking weed raises your odds of getting lung cancer. Here's what researchers know — and don't know — about the connection.
Is Marijuana Harmful?
The link between tobacco smoke and lung cancer is well known. Studies show that marijuana smoke has many of the same harmful substances as tobacco and often more of them. Among the hazards are:
- Benzo(a)pyrene
- Benz(a)anthracene
- Phenols
- Vinyl chlorides
- Nitrosamines
- Reactive oxygen species
People also smoke marijuana in a different way than they smoke tobacco, possibly posing greater danger to the lungs:
- Some people hold in weed smoke as long as possible to get "higher," but that's a myth. In fact, holding weed smoke in your lungs for more than a few seconds can potentially harm your health even more.
- You generally smoke a joint all the way to the end. Tar, the sticky stuff left after burning, has high levels of harmful substances, and it's concentrated at the end of a joint.
When scientists looked at the lung tissue of some people who smoke marijuana regularly, they found changes that are known to signal the future growth of cancer.
Lung Irritants and Marijuana
Smoking weed harms your lungs. It can cause a long-term lung problem called chronic bronchitis. Weed smoke hurts the inside of your breathing tubes, which can lead to coughing, mucus, wheezing, and other lung problems.
Smoking weed can also weaken your body's defense against sickness, especially if you're already sick or taking medicine that weakens your immune system. Weed smoke kills cells that help fight germs and makes more mucus. This could lead to more lung infections, but we don't have strong proof of this yet.
Some studies show that people who smoke weed have thicker and inflamed breathing tubes and damaged lung tissue than those who don't smoke anything or only smoke regular cigarettes.
Besides lung infections, people with HIV who smoke weed raise their odds of getting other infections.
If you have asthma, you shouldn't smoke or vape weed. It can make your cough, wheezing, and shortness of breath worse. You could also have a really bad asthma attack. One survey found that almost one-third of people who smoked weed have a cough.
Does Weed Cause Other Lung Infections?
Weed smoke can carry germs that can make you sick. Here are some of the infections you could get if you smoke weed:
- Aspergillosis: A type of mold called Aspergillus that can grow on marijuana plants causes this infection. It can be very serious for people with weakened immune systems.
- Air pockets in their lungs: People who smoke a lot of weed, especially young and middle-aged adults, can get air pockets in their lungs, which can happen between the lungs or between the lungs and the chest wall.
Vaping Marijuana
Both nicotine and weed vape devices work in a similar way. They heat a liquid or oil until it becomes a vapor you breathe in. Many weed vapes look just like the vapes people use for nicotine or other flavors.
Vaping weed hurts teens and young adults by harming their brains and lungs. Because the brain in early adulthood is busy growing and developing critical and problem-solving skills, weed can be a barrier to achieving these.
These are the possible health problems linked to weed vaping:
- Trouble with focus, problem-solving, and memory
- Slower reaction time and poor coordination, especially when driving
- Lower grades and school performance
- Higher odds of mental health problems like depression, anxiety, or even psychosis, especially if there's a family history
- Addiction
Doctors also link vaping marijuana to thousands of lung injuries and deaths. This is often due to a condition called EVALI (E-cigarette, or Vaping, product use-Associated Lung Injury), which they connect to tetrahydrocannabinol (THC; the active ingredient in marijuana) and vitamin E acetate, a substance sometimes added to vaping liquids. Even though most of these cases involve illegal products, some happen with legal products.
Symptoms of this vaping-related lung illness include:
- Shortness of breath
- Weight loss
- Sweating during the night
- Tiredness
- Digestive problems
- Lower oxygen levels
- Lung failure and death in serious cases
Secondhand Marijuana Smoke
Marijuana smoke has THC, the chemical that causes the "high" from cannabis. If you smoke weed near another person, you're likely to pass THC to them through secondhand smoke. If you or someone else breathes in secondhand cannabis smoke, you might feel high too.
Recent studies show that if someone in your home uses cannabis, like a parent or relative, your child could have detectable levels of THC in their system. This exposure might raise your child's chances of having health problems, but health professionals need more research to fully understand the effects. We already know that using cannabis during your teen years can affect your brain, leading to issues with attention, motivation, and memory.
Marijuana and Lung Cancer
Given what scientists already know, why is it so hard to say how smoking marijuana affects your chances of getting lung cancer?
Studies that have looked for a direct link between the two have conflicting results — some found evidence that ties marijuana to lung cancer, while other data show little to no connection.
The topic is also tough to investigate. Scientists say a few factors limit how reliable the research is.
Most of the research on marijuana dates to when it was still widely illegal. It's hard to gather information about behavior that's against the law. Most studies have asked people to report how often they smoked marijuana, and researchers know that these kinds of surveys, called "self-reported," aren't as reliable as when they collect data in other ways. That's because people don't remember their behavior perfectly or might underestimate or conceal how often they do something that others think is wrong.
Illegal marijuana, unlike tobacco, doesn't have any controls on its strength or quality. People don't use the same amount in one "dose." That makes it hard for researchers to set standards to measure its effects.
Another problem is that many people who smoke marijuana also smoke tobacco, sometimes mixed in the same cigarette. So if they get lung cancer, it's impossible to sort out what substance caused it.
Some marijuana smokers in the studies have been fairly young, which could skew the results. Cancers can take time to grow.
On the other hand, most people who use marijuana don't smoke as much as a tobacco user, which could lower their odds for a problem.
Animal research suggests that some chemicals in marijuana work against tumor growth, which could explain why lung cancer isn't showing up as often as scientists might expect in people who smoke it. The studies on this are in their early days, and researchers need to take a deeper look into this theory.
The Future
Now that marijuana is legal in more places, growers are making the product more standard and stronger. More people are smoking it, too.
Any link between marijuana smoking and lung cancer isn't clear now, but researchers have a chance to move beyond some of the problems that have made studies unclear in the past.
Harm Reduction Tips for Weed and Lung Cancer
If you want to be safe from cannabis, the safest choice is to avoid it altogether. But if you do use it, following these tips can help lower the odds of its harmful effects:
- Avoid mixing with tobacco. Tobacco is highly addictive, and it causes cancer and heart disease. Using weed alone, without tobacco, lowers these chances.
- Don't hold smoke in your lungs. It won't get you higher but, instead, allows more harmful tar and chemicals to stick to your lungs.
- Use proper materials for roaches. Avoid using cigarette filters, as they cause you to inhale more tar. Instead, use a small piece of plain card rolled loosely to allow better airflow.
- Limit the number of rolling papers you use. Stick to three at most. Using too many rolling papers raises the amount of burnt paper you inhale.
- Avoid using harmful materials for pipes. Do not use plastic bottles, rubber hoses, PVC, foil, or aluminum because these can release toxic fumes when heated. Use glass, steel, or brass pipes, which are safer.
- Think about other people. Not everyone enjoys getting high. Avoid smoking near people who don't use it, especially children and people with respiratory issues.
Takeaways
Smoking marijuana may raise your chances of lung cancer, but scientists aren't sure yet. Marijuana smoke has many of the same harmful substances as tobacco smoke, which could damage lung tissue and lead to cancer. Plus, smoking weed can cause chronic bronchitis, weaken your immune system, and raise your odds of lung infections. Doctors and scientists link vaping marijuana to lung injuries and mental health issues, especially in teens and young adults. If you smoke marijuana, avoid mixing it with tobacco, holding the smoke in your lungs, or using harmful materials to lower potential health problems.
Marijuana Lung Cancer FAQs
What are potential carcinogens in marijuana smoke?
Marijuana has possible cancer-causing chemicals, including tar, ammonia, polycyclic aromatic hydrocarbons, carbon monoxide, cyanide, benzene, and others.
