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How do e-cigarettes like Juul impact your health?

As vaping grows in popularity and the industry leader, San Francisco’s Juul, sells billions of dollars in vaping products each year, one key question remains unanswered: How do e-cigarettes affect your health?

The short answer is no one knows the long-term health impacts of e-cigarettes because they have not been studied long enough, or in large enough groups of people, to draw definitive conclusions. E-cigarettes have been on the market only since around 2007, with the most recent versions like Juul becoming available in 2015.

But researchers and medical experts say there is a growing body of preliminary evidence — based on animal studies, cell experiments and short-term studies on small groups of people — indicating that e-cigarettes, while less harmful than conventional tobacco cigarettes, may do some damage to the human body.

The extent of that damage, and how long it may last, is unclear.

“We can comfortably say e-cigarettes will be less harmful than cigarettes, and substantially so, for certain health outcomes. But we can also say it’s more dangerous than air,” said Adam Leventhal, who studies tobacco addiction at the University of Southern California’s Keck School of Medicine. “It’s somewhere in between.”

One study by UC Riverside researchers, published this month in Chemical Research in Toxicology, found that Juul products have a higher nicotine concentration than other e-cigarette brands, at a level high enough to be toxic to human cells.

“The concentrations of nicotine and some flavor chemicals in Juuls are high enough to be a concern, and should be evaluated further in humans,” said Prue Talbot, the paper’s lead researcher and professor of molecular, cell and systems biology.

A Juul spokesman did not comment on the UC Riverside findings, instead citing a recent Juul-sponsored study showing that adult cigarette smokers who switched to Juul showed the same reductions in urine and blood biomarkers associated with cigarettes as adult smokers who stopped smoking altogether during the same five-day period.

Many researchers agree that e-cigarettes appear to cause a reaction from the respiratory system that often leads to coughing, wheezing and worsening of asthma. Vaping also leads to short-term spikes in heart rate and blood pressure, likely because of the nicotine in e-cigarettes, but it’s unclear whether or how damaging that may be decades down the line.

The health impacts also depend on who’s doing the vaping and what their previous exposure to tobacco has been. Teens who have never smoked cigarettes before may experience coughing or wheezing after using e-cigarettes, while many adults who have smoked cigarettes for years report improved health when switching to vaping. This is because many of the health problems caused by conventional cigarettes are attributed to inhaling combustible carcinogens in tobacco. E-cigarettes, by comparison, do not burn toxins but rather heat them to a vapor — and nicotine liquid heated to a vapor is believed to be less harmful.

“In terms of health effects in kids that have been documented, the main thing has been respiratory problems, more coughing, more wheezing, aggravation of asthma,” said Neal Benowitz, a UCSF tobacco researcher who published a 2017 paper that found that e-cigarettes might pose some cardiovascular risk but less risk than that of cigarette smoking.

One of the most comprehensive analyses yet on e-cigarettes is a 2018 report by the National Academy of Sciences, Engineering and Medicine, which looked at 800 peer-reviewed e-cigarette studies on human health effects, harm reduction and smoking cessation. It found conclusive evidence that most e-cigarettes contain and emit many potentially toxic substances, and that the characteristics of those substances depend greatly on the type of e-cigarette and how it’s used.

The analysis found substantial evidence that e-cigarette aerosol can affect the cells lining the blood and lymphatic vessels — but the long-term consequences of this are uncertain. It also found substantial evidence that some chemicals in e-cigarette aerosols, such as formaldehyde, are capable of causing DNA damage.

For youth and young adults, there is substantial evidence e-cigarette use increases the risk of using combustible tobacco cigarettes, the academy found. But for adult cigarette smokers, there is moderate evidence that frequent use of e-cigarettes is associated with increased likelihood of quitting tobacco cigarettes. A recent study in the New England Journal of Medicine echoes this, finding that e-cigarettes are more effective in helping smokers quit cigarettes than nicotine patches and gum; experts, though, point out that the e-cigarettes used in that study were older versions that had a lower level of nicotine than Juul and other newer products, and that they were used in conjunction with behavioral support like counseling.

There is insufficient evidence that e-cigarette use is associated with or causes long-term changes in heart rate or blood pressure, and no studies to determine whether it causes heart disease, stroke or respiratory diseases, the academy concluded.

There are limitations to many of the preliminary studies. Some have been conducted on animals rather than humans, are done under conditions that do not mimic real-world use of vaping products, do not produce enough data to be considered conclusive, focus on one aspect such as the role of flavors in attracting youth, or are cross-sectional — studying people who both use e-cigarettes and are at risk of a heart attack, for instance — so the results do not necessarily apply to a broader population.

The Food and Drug Administration and the National Institutes of Health are trying to determine the long-term health effects of e-cigarettes for the general population in the Population Assessment of Tobacco and Health study, which the agencies began in 2013.

Catherine Ho is a San Francisco Chronicle staff writer. Email: cho@sfchronicle.com Twitter: @Cat_Ho

Article source: https://www.sfchronicle.com/business/article/How-do-e-cigarettes-like-Juul-impact-your-health-13783117.php

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