Clear The Air News Tobacco Blog Rotating Header Image

February 14th, 2016:

Vaping may threaten brain, immunity and more

New studies in animals and human cells find some risks almost seem worse than from smoking

WASHINGTON, D.C. — Today, more U.S. teens vape than smoke. Many of those teens may have assumed that electronic cigarettes are a safe, high-tech alternative to tobacco. And it’s true that e-cigs don’t emit many of the 7,000 chemicals found in tobacco smoke. Still, teens are fooling themselves if they think vaping is harmless, scientists reported February 11 and 12 at a major science meeting.

The new data — from animals and human cells — show that the vapors released by e-cigarettes can alter the activity of genes. Many, many genes. One study also linked e-cig vapors to reproductive harm in males. And data emerging in yet another study linked e-cigarette use to a form of heart disease. The toxicologists shared their findings, here, at the American Association for the Advancement of Science (AAAS) annual meeting.

If used as a means to eventually give up tobacco altogether, then vaping might have some value, says Ilona Jaspers. She works at the University of North Carolina at Chapel Hill. Still, Jaspers is not sure. And for teens who never smoked, vaping “may actually be introducing new [health] risks,” she worries.

Hurting the infection-fighters

Jaspers’ team studied cells that they had scraped from the inside of the noses of healthy people. Some were smokers. Some vaped. Others did neither. The researchers then measured the activity of 594 genes in these cells. All of the genes had earlier been linked with the immune system, which plays a major role in fighting infections.

Among smokers, the activity of 53 genes was depressed, or lower than usual, when compared to those who neither smoked nor vaped. Among vapers, the activity of those same 53 genes was depressed, Jaspers reports. But so was the activity of another 305 genes. By this measure, vaping had a bigger effect on genes related to immunity than smoking did.

The affected genes normally recruit and aid the body’s cells in fighting bacteria or other germs. So the new data suggest that smokers — but especially vapers — “may be more susceptible to any kind of infection,” Jaspers says.

To test that, Jaspers’ team collected immune cells from healthy people. The scientists then exposed those cells to the flavored liquids used to create vapors in e-cigarettes. Tested cells included blood neutrophils (NU-trah-fils) and lung macrophages (MAK-row-FAY-gez). The body normally tasks both with gobbling up and killing bacteria.

Some of the liquids proved disturbingly effective at preventing those immune cells from doing their job. One example was a cinnamon-flavored compound. It was found in several e-juices, including flavorings not associated with cinnamon, such as cola.

Vaping’s impact on behavior

Judy Zelikoff works at New York University’s Langone Medical Center in Tuxedo. Her team also found vaping-related changes in genes. In their case, they focused on genes in the brain that play a role in behavior and mental health.

The scientists exposed pregnant mice to e-cig vapors. Then, once the pups were born, they too got exposed for a month. That is when mice reach young-adulthood. The animals breathed in vapors at concentrations scaled to be similar to what a vaping person might encounter. Then Zelikoff’s group tracked the activity of genes in the animals’ frontal cortex. This brain region is associated with planning and using inputs from the senses (like sight, smell and sound) to understand their environment.

In these animals, whether the e-cig vapors contained nicotine made a big difference. Nicotine is the addictive substance in tobacco that keep smokers yearning for another puff.

Male mice exposed to nicotine-laced vapors showed no gene-activity changes. Among females, however, vapors laced with nicotine altered the activity levels of 148 genes in the brain’s frontal cortex. But among rodents exposed to vapors free of nicotine, a whopping 830 or more genes in the frontal cortex showed substantially altered activity. That activity was either much higher or lower than in unexposed mice. Usually, over- or under-activity of genes is not considered healthy. Both males and females were about equally affected.

“We were so surprised” by the exaggerated effect of no-nicotine vapors, Zelikoff says. In fact, she notes, her team was so shocked “that we repeated the [experiment] two more times.”

The nature of the affected genes would suggest the animals could behave differently than normal. Some of those changes might even point to possible mental illness, Zelikoff says. To probe that a bit further, her group teamed up with researchers at the University of Rochester in New York. They found that mice in both the nicotine and no-nicotine group indeed showed altered behavior.

Young-adult mice exposed to nicotine-free e-cig vapors in the womb tended to move at almost twice the pace of unexposed mice. They moved faster still if they had been exposed to nicotine. Both groups of mice also jumped more. And mice exposed to vapors also stood on their hind legs more than those that had not been exposed. All of these “are behaviors that are reflective of increased — or hyper — activity,” Zelikoff reports. These behaviors also might be a sign the mice were stressed or agitated. Her group is now exploring possible effects of vaping on memory and mental disorders.

Yet more signs of potential problems

The New York University group also uncovered reproductive problems in the young-adult male mice that had been exposed to e-cig vapors in the womb. Concentrations of their sperm, the male cells used in mating, were only about half as high as in unexposed mice. For mating to be successful, sperm have to move and find an egg to fertilize. But the share of motile sperm — those moving normally — was only a fifth as high as in unexposed males. This suggests that such mice might have a hard time producing a new generation of mice.

Finally, exposing mice to e-cig vapors increased a buildup in their arteries and blood vessels of plaque (PLAK), reports Daniel Conklin. He’s a toxicologist at the University of Louisville in Kentucky. The increased plaque is a sign of emerging atherosclerosis (ATH-ur-oh-sklair-OH-sis). Cigarette smoke also boosted the buildup of plaque.

In both vaping and smoking, he notes, it appears that toxic aldehydes are contributors. Among such compounds are acrolein (AK-roh-leen), formaldehyde (For-MAL-duh-hyde) and acetaldehyde (AA-sit-AL-duh-hyde). These findings, he says, appear to indicate that electronic cigarette vapors “could adversely impact the cardiovascular health of users.”

“We’re really at the beginning of understanding the toxicity of emerging [tobacco] products” such as e-cigs, says Neal Benowitz. He’s a physician who studies tobacco and health at the University of California, San Francisco. Certainly, he says, there has been a general perception that vaping is safer than smoking. The challenge to science is teasing out if that is true. For now, he says, “We really don’t know.”

Adds Zelikoff, “I’m a firm believer in the precautionary principle.” This means that where there are warning signs, they should be heeded. So if she were pregnant, she says, “I would look at these animal data with a great deal of respect.”