Research on the impact of cannabis on health is in its infancy, because, historically, it has been difficult to study cannabis use because weed has been illegal.  

Here’s some of what’s known:  

Frequent smoking of marijuana is associated with chronic bronchitis, throat and bronchial inflammation.  

Marijuana smoke contains carcinogens, such as benzoprene and benzanthracene.

It does not appear that smoking marijuana causes lung cancer.

Study: People who only smoked marijuana had higher blood and urine levels of several smoke-related toxins than nonsmokers. Those toxins are linked to anemia, liver and neurological damage, cancer and other health issues.

Study: Teens are about twice as likely to report “wheezing or whistling” in the chest after vaping marijuana than after smoking cigarettes or using e-cigarettes. 

Study: 75% of the lungs of people much younger than 50 who smoked both tobacco and cannabis had emphysema, a disease of the small airways that causes damage to the air sacs in the lungs. Only 5% of the study’s nonsmokers had the disease. 

According to the American Lung Association, smoking marijuana suppresses the immune system and can leave users exposed to a mold that can grow on marijuana.