Mice heavily exposed to e-cig vapor develop lung cancer

Researchers find e-cigarettes have caused lung cancer in mice

Researchers find e-cigarettes have caused lung cancer in mice

A new study on mice suggests that vaping may also cause lung cancer, for instance. So as to develop those discoveries, they exposed 40 mice to significant levels of e-tobacco "smoke" for 54 weeks, or a little more than a year.

The FDA is now hammering out its guidance to eliminate all non-tobacco flavors of e-cigarettes, including mint and menthol, from the market to deter underage usage.

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

Meanwhile, none of the 20 mice that were exposed to e-cigarette smoke devoid of nicotine had cancer growth over the four years researchers studied the mice. The mice in the study also didn't inhale the smoke like a human would, but were instead surrounded by it (whole body exposure). Only one of the 17 mice exposed to the zero-nicotine e-cigarette smoke developed hyperplasia. 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-cigs, say the authors. These are nitrosamines that deteriorate DNA and create cancer cells.

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.

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.

Conventional thinking, says Dr. Tang, has been that smoke from cured tobacco deposits nitrosamines into a smoker's organs and blood. The researchers reported that e-cig vapor induced DNA mutations linked to lung cancer. Many studies have also shown that human and mouse cells also have ample supplies of cytochrome p450, which further converts NNN and NNK into compounds (e.g. formaldehyde and CH3N=NOH) that can react with DNA to form damaging adducts (e.g. gamma-OH-PdG and O6-methyl-dG), the researchers say.

"Our next step in this line of work will be to expand the number of mice studied, to shorten and prolong e-cigarette exposure time, and to further investigate the genetic changes caused by e-cigarette smoke", said the paper's co-author Herbert Lepor at NYU.

The effects of e-cig smoke on humans "may not be known for a decade to come", but the study is the first to definitively link vaping nicotine to cancer, CNBC reports.

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