New York University Study Finds Vaping May Cause Cancer in Mice

On October 8, news from the Los Angeles Times reported that a study on mice showed that long-term exposure to nicotine-containing e-liquids significantly increases the risk of cancer.

The study found that after inhaling electronic vapor for 20 hours a week over a year, 22.5% of the mice had cancerous tumors in their lung linings, while 57.5% showed lesions in their bladder tissue, which could be precursors to cancer.

In contrast, only 5.6% of the control group, which only inhaled filtered air, developed bladder growths. Additionally, a group of mice exposed to e-chemical substances without nicotine did not develop lung tumors, with only 6.3% showing precancerous bladder growth.

The scientists conducting this study emphasized that more research is needed to understand whether e-cigarettes can cause cancer in humans. However, they hope their findings will encourage people to think twice before trying e-cigarettes, which are widely perceived by teenagers and young adults as a safe alternative to smoking.

"Right or wrong, millions of young people are using these, and we need long-term, extensive population studies to draw conclusions," said the lead researcher from New York University.

"Researchers need reliable evidence to guide people's choices, and there is no doubt that nicotine can harm the cells of organs, including the lungs," said Tang, who studies how tobacco smoke promotes lung and bladder cancer. "Now, we can try to find measures to prevent e-cigarettes from causing cancer."

E-vaping has been linked to heart attacks, seizures, and burns from exploding devices. At least 1,080 cases of vaping-related lung injuries have been reported, which clearly reminds us that it is still too early to say whether e-cigarettes can replace smoking.

To better understand the long-term effects of nicotine, Tang and his collaborators exposed 45 mice to nicotine aerosol dissolved in propylene glycol and vegetable glycerin (a medium for vaporizing liquids), while another group of 20 mice was exposed to the same medium without nicotine. Over 54 weeks, the animals were subjected to aerosol mixtures for 4 hours a day, five days a week.

A third group of 20 mice spent time in a room with filtered air. (This study was limited to 54 weeks to minimize the potential impact of age-related cancers.)

At the end of the 54 weeks, the remaining animals were euthanized, and researchers examined their tissues. Among the 40 mice in the nicotine group, 9 had tumors in their lungs. Tang noted that he was not surprised to find tumors in the control group, as mice generally have an increased likelihood of developing lung cancer.

Additionally, researchers found that among the 40 mice exposed to nicotine vapor, 23 developed bladder hyperplasia, which is characterized by uncontrolled cell proliferation in the bladder wall before cancer occurs. In contrast, only 1 out of 16 mice exposed to non-nicotine vapor developed bladder growth, and none of the 17 mice inhaling filtered air showed any growth.

The researchers concluded that the differences were significant enough to conclude that nicotine aerosol is a cause of increased tumor risk. For example, mice inhaling nicotine mixtures were eight times more likely to develop lung tumors than those not exposed to nicotine.

Dr. Mark Litwin, chair of the Department of Urology at UCLA, stated, "This is compelling and very frightening. When DNA-encoded instructions are disrupted, cells go haywire and continue to reproduce uncontrollably. That is a hallmark of cancer. At first glance, it already looks like precancerous tissue."

Researchers also found that several mice exposed to e-cigarette vapor (with or without nicotine) developed abdominal or skin tumors, while none were found in the filtered air group. However, these differences were small and may have been coincidental.

This work was funded by the National Institutes of Health.

Tang's team published a study last year indicating that when nicotine is introduced into mammalian cells, a molecule called nitrosamine reacts with nicotine, forming carcinogens in both mice and humans.

Tang stated, "We cannot say that e-cigarettes will ultimately lead to cancer in humans, but the mechanisms at play here are very clear: the same carcinogens shown in other studies are causing human cancers. We can infer that using e-cigarettes can lead to genetic material damage and disrupt cells, and the longer the smoking duration, the longer the cumulative time."

He added that the smoke extracted from e-cigarettes must undergo more thorough research before being considered safe or marketed as such. #p#分页标题#e#

The author acknowledges that this study has several limitations. It involved a small number of mice that were merely surrounded by vapor rather than inhaling it like human e-cigarette users.

Dr. Herbert Lepor, chair of Urology Research at NYU Langone Health and a study author, stated that the research team plans to use more mice to test short-term and long-term exposure, and researchers also plan to closely examine genetic changes associated with inhaling e-cigarette smoke.

Experts unanimously agree that this new study does not answer the swirling questions surrounding the current outbreak of vaping-related lung diseases, but it does confirm concerns about the long-term effects of e-cigarettes.

Litwin stated, "Teenagers will tell you that using e-cigarettes is safer because it eliminates all the carcinogenic components of cigarettes. It turns out that this is not the case."