Lung illnesses and deaths from vaping have been grabbing headlines for months, and now two new studies offer fresh evidence pointing to long-term respiratory concerns.
The studies link the use of electronic cigarettes to asthma and chronic obstructive pulmonary disease (COPD).
"These studies add to the body of evidence on the relationship between electronic cigarette use and lung conditions," said Dr Albert Osei, a postdoctoral fellow at Johns Hopkins University School of Medicine in Baltimore. He's lead author of a study published earlier this month in the American Journal of Preventive Medicine.
The studies cannot definitely prove a cause-and-effect link, he noted, adding: "We believe this warrants further longitudinal studies."
Destruction of lung tissue
Introduced to the US market more than a decade ago, e-cigarettes are marketed as less harmful than traditional tobacco cigarettes, and as a way to help quit smoking. In 2016, almost 11 million American adults used e-cigarettes.
Most have a vaporisation chamber, a nicotine cartridge that can include flavouring and a rechargeable battery. The vapour they produce is inhaled into the lungs – a process called vaping.
Past studies have suggested the vapour may irritate airway cells, impair their ability to fight infection, and lead to destruction of lung tissue. A study just published in December found that e-cigarette users are also at significantly higher risk of chronic lung diseases such as asthma, bronchitis, emphysema and COPD.
Vaping been linked to a nationwide outbreak of serious lung illness. As of 7 January, there have been more than 2 600 illnesses and 57 deaths – many linked to vaping products with THC, the component in marijuana that produces a high. An additive called Vitamin E acetate that makes the THC last longer may be the culprit, according to US Centers for Disease Control and Prevention.
Osei's study looked at a database of more than 705 000 adults.
Almost 65 000 smoked regular cigarettes. More than 25 000 smoked e-cigarettes; their average age: 30 to 34. More than 200 000 were former traditional smokers.
Higher odds of COPD
About 2% of smokers reported using both traditional and e-cigarettes. More than 53 000 in the group said they had COPD, chronic bronchitis or emphysema.
In people who had never smoked regular cigarettes, e-cigarette use was associated with 75% higher odds of COPD, the study found. Daily users of e-cigarettes had 2.6 times higher odds of COPD than people who never smoked regular cigarettes.
The second study – published recently in the journal BMC Pulmonary Medicine – included more than 400 000 adults who never smoked regular cigarettes. More than 34 000 had asthma. Just 3 100 people currently used e-cigarettes. Their average age: 18 to 24.
The risk of asthma was 39% higher in current e-cigarette users than in people who had never vaped. And the more people vaped, the higher their asthma odds, the study reported.
Like Osei, the head of a pro-vaping advocacy group noted that these studies don't prove that e-cigarettes were responsible for either condition.
It's possible that people with asthma or COPD might have had their conditions before using e-cigarettes, said Greg Conley, president of the American Vaping Association.
Majority young people
"There is no plausible mechanism by which vaping, which exposes users to far fewer toxins than cigarette smoking, could cause COPD in a period of a few years," he said. "Even among heavy smokers, several decades are required for COPD to develop."
Dr Len Horovitz is a pulmonary specialist at Lenox Hill Hospital in New York City who also reviewed the findings.
"Long gone are the days when makers of e-cigarettes could claim that this form of nicotine use was not harmful," he said. There is no safe smoking or vaping."
Study author Osei agreed, pointing out that both combustible and e-cigarettes contain nicotine.
"The majority of people using electronic cigarettes are young people. Over time, we will have a generation who becomes nicotine-dependent from using electronic cigarettes," Osei said. "As a public health physician, I cannot say that electronic cigarettes are without risk."
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