WHAT YOU NEED TO KNOW:
- A new study claimed to have discovered evidence that exposure to nicotine from e-cigarette vapor causes lung cancer in mice.
- Funded by the National Institutes of Health, the new research from New York University is the first to conclusively associate vaping nicotine to cancer.
- “So, the probability is very high that e-cigarette vapor is a human carcinogen,” lead author Moon-Shong Tang told Gizmodo via email.
A new study published Monday in the Proceedings of the National Academy of Sciences found additional evidence that e-cigarette vapor can cause certain kinds of cancer. But the researchers say further research is needed before it can be determined if the same is true in humans.
There’ve been previous reports that e-cigarette vapor, just like tobacco smoke, could cause cancer. A previous study by the same team of scientists at New York University’s School of Medicine discovered that vaping could damage DNA in the bladder and lung cells of both mice and people enough to increase their risk of turning cancerous.
Other researchers have found the presence of chemicals known to be carcinogenic in e-cigarette vapor, especially from flavored products. The latest study is the first to link e-cigarettes to cancer.
For over a period of 54 weeks, the scientists exposed groups of mice to three different conditions, each lasting four hours a day, five days a week. One group of mice spent time in a chamber filled with e-cigarette vapor created by a machine that mimicked a typical vaping product, meaning that nicotine was heated and aerosolized from a liquid containing the solvents propylene glycol and vegetable glycerin. Another group was exposed to vaporized air just containing the solvents, and the third simply spent their time breathing filtered air.
Nine of the 40 mice exposed to typical e-cigarette vapor developed lung cancer after the experiment, while only one of the mice in either control group developed cancer. More than half of the mice exposed to e-cigarette vapor also developed hyperplasia, an enlarged bladder, which is a risk factor for bladder cancer.
Molecular biologist Moon-Shong Tang, the lead author of the study, said the team also found that certain cancer-causing compounds, called nitrosamines, are formed in the bodies of mice when exposed to vapor filled with nicotine. Nitrosamines are known carcinogens in both mice and humans.
“So, the probability is very high that e-cigarette vapor is a human carcinogen,” Tang told Gizmodo via email.
He added: “It takes two decades or more for a life-time smoker to develop lung cancer. If tobacco smoke-induced lung carcinogenesis is a paradigm for e-cig carcinogenicity, then it will take at least another decade to have e-cig-related human lung cancer to show up.”