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E-cigarettes linked to new health risks: vaping may affect immune system, heart, sperm and behavior.

Many people have turned to electronic cigarettes in hopes of avoiding the heart and cancer risks associated with smoking conventional tobacco products. But vaping increasingly appears far from benign, a trio of toxicologists reported February 11 and 12.

If used as a means to totally wean people off of tobacco products, then e-cigarettes might have value, conceded Ilona Jaspers of the University of North Carolina at Chapel Hill. But she's not sure. Unpublished data that she and the others presented link e-cigarette products to a host of new risks. So vaping may not eliminate risks associated with conventional smoking as some have thought, Jaspers maintained, "and may actually be introducing new ones."

Her group examined scraped cells from the noses of otherwise healthy people who had a history of smoking, vaping or doing neither. The researchers then measured in these cells the activity levels of 594 genes associated with the body's ability to fight infections. Among smokers, the activity of 53 genes was substantially diminished, compared with people who neither smoked nor vaped. Among vapers, those same 53 genes showed significantly diminished activity as did 305 others, Jaspers reported.

The normal role of these genes suggests that the lung and nasal tissue of smokers--and especially vapers--"may be more susceptible to any kind of infection," Jaspers said.

To test that possibility, Jaspers' team collected immune cells from healthy human volunteers, then exposed those cells to flavored liquids used in e-cigarettes. Tested cells included blood neutrophils and lung macrophages, both normally tasked with gobbling up and killing bacteria. Some of the liquids proved disturbingly effective at suppressing the ability of those immune cells to do their job, Jaspers reported.

One compound with a particularly suppressive effect was the cinnamon-flavored cinnamaldehyde. Jaspers said she was surprised to find cinnamaldehyde in some of the noncinnamon-flavored liquids, including a cola one.

Judy Zelikoff of the New York University Langone Medical Center in Tuxedo also looked at genes affected by e-cigarette vapors. Her group exposed mice developing in the womb, and for a month after birth, to vapors at concentrations calculated to be comparable to what a vaping pregnant woman might encounter. Then Zelikoff tracked the activity of genes in the mice's frontal cortex, a brain region associated with planning and integrating the senses to understand the environment.

Whether the e-cigarette vapors contained nicotine made a big difference.

Males exposed to nicotine-laced vapors showed no gene-activity changes. Among females, vapors laced with nicotine appeared to alter the activity levels of 148 genes in the brain's frontal cortex. But among mice exposed to nicotine-free vapors, a whopping 830 or more genes in the frontal cortex showed altered activity--either much higher or lower than in unexposed mice. Both males and females were about equally affected.

Zelikoff said that she was so surprised by the exaggerated effect of the nicotine-free vapors that her team repeated the experiment two more times.

Zelikoff's group then teamed up with researchers at the University of Rochester in New York to investigate whether the gene-activity changes alter behavior. Mice in both the nicotine and no-nicotine groups showed behavioral changes. When adult mice that had been exposed to nicotine-free vapors in the womb moved, they tended to do so at almost twice the pace as unexposed mice. Mice 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 reported, "and possibly agitation." Her group is now exploring possible effects on memory and mental disorders.

Her group also uncovered reproductive problems in young adult male mice exposed to e-cigarette vapors in the womb. Their sperm concentrations were roughly half the value as those in unexposed mice. And their share of motile sperm was only a fifth as high as in unexposed males.

Exposing mice to e-cigarette vapors also increased plaque buildup in the arteries, a sign of emerging atherosclerosis, reported Daniel Conklin of the University of Louisville in Kentucky. Cigarette smoke did too. In both cases, he noted, toxic aldehydes, such as acrolein, formaldehyde and acetaldehyde, appear to be contributors. As such, he concluded, e-cigarette vapors "could adversely impact the cardiovascular health of users."

Neal Benowitz of the University of California, San Francisco notes that "we're really at the beginning of understanding the toxicity of emerging products." There is a lot of complexity to understanding what goes into the vapors and the tissues that may be at risk. Certainly, he says, there has been a general perception that vaping is safer than smoking (SN:7/11/15, p. 18). "The challenge to science," he says, will be to tease out: "Is this really true?" For now, he says, "we really don't know."

Perhaps it's true, Zelikoff said. "But I'm a firm believer in the precautionary principle." If she were pregnant, she said, "I would look at these animal data with a great deal of respect."
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Title Annotation:BODY & BRAIN
Author:Raloff, Janet
Publication:Science News
Geographic Code:1USA
Date:Mar 5, 2016
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