E-cigarette smoke caused lung cancer in mice

Researchers find e-cigarettes have caused lung cancer in mice

Researchers find e-cigarettes have caused lung cancer in mice

E-cigarette vapor causes lung cancer and potentially bladder cancer in mice, according to researchers at New York University.

Of the 40 mice exposed to e-cigarette vapor with nicotine over 54 weeks, 22.5% of them developed lung cancer, and 57.5% developed precancerous lesions on the bladder.

There've been hints that e-cigarette vapor, much like tobacco smoke, could be carcinogenic.

"Tobacco smoke is among the most risky environmental agents to which humans are routinely exposed, but the potential of E-cig smoke as a threat to human health is not yet fully understood", says Moon-shong Tang, a professor at NYU's Departments of Environmental Medicine, Medicine, and Pathology.

Dr. Tang admitted that there are limitations to the study - the mice were exposed to smoke outside their bodies instead of inhaling it like humans would, for example - and the results in mice can't be directly compared to the results in humans. Only one of the 17 mice exposed to the zero-nicotine e-cigarette smoke developed hyperplasia. Instead, the study argued that the smokes coming from electronic cigarettes must be thoroughly studied before it is declared safe. These mice are often used in cancer research because it usually takes a long time to spot whether any particular thing can cause cancer (that said, they aren't genetically predisposed to lung cancer). Partly as a result of such public messaging, 3.6 million junior high and high school students having embraced e-cigarettes, say the authors.

Although the chemicals are 95 percent lower in e-cigarettes, the new study showed that mammalian cells could directly react with nicotine to form nitrosamine, then resulting in DNA damage.

Conventional thinking, says Dr. Tang, has been that smoke from cured tobacco deposits nitrosamines into a smoker's organs and blood.

A related study conducted by the University of Southern California in February, found that e-cigarette users developed some of the same molecular changes in oral tissue that cause cancer in cigarette smokers.

"Our results support the argument that the nicotine-derived DNA adducts are likely the main causes for carcinogenesis in mice exposed to E-cig smoke", said study author Dr. Herbert Lepor.

Indeed, the mice had DNA mutations. "Tobacco smoke is among the most unsafe environmental agents to which humans are routinely exposed, but the potential of E-cig smoke as a threat to human health is not yet fully understood", says Tang, a professor in the Departments of Environmental Medicine, Medicine, and Pathology.

Along with Tang and Lepor, study authors were Xue-Ru Wu, Hyun-Wook Lee, Yong Xia, Fang-Ming Deng, Andre Moreira, Lung-Chi Chen, and William Huang in the departments of Environmental Medicine, Medicine, Pathology and Urology at NYU School of Medicine.

The first study definitively linking vaping to cancer was published yesterday.