Prior to the study’s release, the prevailing assumption was that people who smoked marijuana would face the same lung damage and cancer risks as tobacco smokers, but to the surprise of even the researchers, the findings indicated no increased risk of lung cancer. Marijuana smoking also did not appear to increase the risk of head and neck cancers, the study showed.

The findings suggest that the active chemical compounds in marijuana — particularly tetrahydrocannabinol (THC) — may indeed counteract the cancer-causing properties associated with inhaling smoke into the lungs. Researchers speculated that THC causes cells to die before becoming cancerous.

“This study refutes yet another drug war fallacy: that marijuana smoke causes cancer. One by one, the myths and outright lies about marijuana are falling by the wayside due to sound science devoid of politics,” said Ethan Nadelmann, executive director of the Drug Policy Alliance. “We can now clearly see that the most negative consequences of marijuana revolve around the fact that it is illegal.”

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