A recent outbreak of deadly lung illnesses linked to vaping has put the practice in health professionals’ and regulators’ crosshairs, says a Scientific American report. Now the first longitudinal population-based study of e-cigarette use in a representative sample of US adults suggests it increases the risk of many chronic lung illnesses, to – especially when combined with smoking combustible tobacco.
Most of the media coverage of vaping has focused on the short-term, or acute, health impacts. More than 2,500 cases of e-cigarette, or vaping, product use–associated lung injury (EVALI) have been reported across all 50 US states and the District of Columbia, as well as in Puerto Rico and the US Virgin Islands; 54 deaths have been confirmed to date. “Black market” products containing THC (the primary psychoactive ingredient in marijuana) were the mostly commonly reported by EVALI patients, but health authorities have not ruled out risks of lung injury from other vape products.*
The new research suggests that e-cigarettes may also cause long-term health problems. The study found that people who reported using the devices were more likely to develop lung illnesses such as chronic obstructive pulmonary disease (COPD), chronic bronchitis, emphysema or asthma. E-cigarettes have been touted as a harm-reduction method for helping smokers quit, and the new findings could challenge that.
“One of the problems that we've had with the whole e-cigarette debate is it’s asking this abstract question: Are e-cigarettes less dangerous than cigarettes? The answer to that is: if you’re a never smoker who never vaped, the e-cigarettes aren’t as bad as the cigarettes,” says study co-author Stanton Glantz, a professor of medicine at the University of California – San Francisco. But “in the real world, most adult e-cigarette users are dual (e-cigarette and combustible tobacco) users – and that’s worse than (just) smoking.”
Like conventional cigarettes, e-cigarettes contain nicotine and various toxic substances that have been shown to disrupt lung function. But e-cigarettes also contain material such as propylene glycol, flavourings such as diacetyl (for a butter taste) and cinnamaldehyde (for cinnamon), as well as heavy metals. Previous studies in animals have shown that exposure to e-cigarette vapor is linked to lung inflammation and depressed immune activity, and repeated exposure appears to cause lung damage that resembles COPD. Most of the studies in humans have been observational, but they have found an association between e-cigarette use and respiratory disease. And a longitudinal study of people with COPD found that smoking e-cigarettes was linked to exacerbations of the disease and a faster decline.
In the new study, Glantz and his UCSF colleague Dharma Bhatta analysed data from the Population Assessment of Tobacco and Health (PATH) Study, a longitudinal study of adult tobacco use and health in the US. They used data collected from three consecutive time points, or “waves,” between 2013 and 2016. Respondents were asked whether they currently or previously used e-cigarettes or combustible tobacco (including cigarettes, cigars or cigarillos), or both, as well as whether they had ever been diagnosed with COPD, chronic bronchitis, emphysema or asthma.
Glantz and Bhatta found that people who reported being current or former e-cigarette users at Wave 1 of the study had about a 30 percent higher risk of developing a respiratory disease at Waves 2 and 3, compared with people who had never used the devices. This danger was not as dire as that of current tobacco smokers at Wave 1, who had about a two-and-half-times higher chance of respiratory illness in later waves. But people who used both e-cigarettes and combustible tobacco had the greatest risk – they were 3.3 times as likely to develop a respiratory disease as someone who had never smoked or used e-cigarettes. The findings suggest e-cigarette use is a risk factor for respiratory disease independent of conventional smoking.
Robert Tarran, a professor of cell biology and physiology at the University of North Carolina at Chapel Hill, who was not involved with the paper, says the findings were not all that surprising – but the fact that this was a longitudinal study strengthens what previous observational ones have found. “It basically confirms what people in the field were thinking, which is that vaping isn’t good for you,” Tarran says.
Glantz says he was somewhat surprised that he and Bhatta could detect the increased disease risk in just two years – the length of time over which people were tracked in the PATH Study. They also calculated whether switching completely from conventional smoking to e-cigarettes lowered the risk of disease and found that it did. Almost none of the people who used e-cigarettes at Waves 2 and 3 of the study had stopped smoking combustible tobacco, however. Instead smoking both e-cigarettes and combustible tobacco – so-called dual use – was much more common.
The concept that smokers would transition from using cigarettes to e-cigarettes and substantially reduce their health risks is “not a crazy idea,” says Glantz, who is also a non-smokers’ rights activist. “But if you look at actual use behaviours, they multiply. And since most people are dual users, you’re getting increased harms.” In addition, there is the fact that millions of young people who are not regular smokers are getting addicted to e-cigarettes, he adds.
The mechanism of lung damage with chronic e-cigarette use is probably different from that behind EVALI, Glantz notes. About 80% of those hospitalised in the EVALI outbreak reported vaping THC, and the lung damage in those patients resembled that caused by chemical burns. The US Centres for Disease Control and Prevention has identified vitamin E acetate – a type of oil used as a thickening agent in some THC vaping products – as a possible chemical of concern, although the agency is exploring other possible mechanisms.
Abstract
Introduction: E-cigarettes deliver an aerosol of nicotine by heating a liquid and are promoted as an alternative to combustible tobacco. This study determines the longitudinal associations between e-cigarette use and respiratory disease controlling for combustible tobacco use.
Methods: This was a longitudinal analysis of the adult Population Assessment of Tobacco and Health Waves 1, 2, and 3. Multivariable logistic regression was performed to determine the associations between e-cigarette use and respiratory disease, controlling for combustible tobacco smoking, demographic, and clinical variables. Data were collected in 2013–2016 and analyzed in 2018–2019.
Results: Among people who did not report respiratory disease (chronic obstructive pulmonary disease, chronic bronchitis, emphysema, or asthma) at Wave 1, the longitudinal analysis revealed statistically significant associations between former e-cigarette use (AOR=1.31, 95% CI=1.07, 1.60) and current e-cigarette use (AOR=1.29, 95% CI=1.03, 1.61) at Wave 1 and having incident respiratory disease at Waves 2 or 3, controlling for combustible tobacco smoking, demographic, and clinical variables. Current combustible tobacco smoking (AOR=2.56, 95% CI=1.92, 3.41) was also significantly associated with having respiratory disease at Waves 2 or 3. Odds of developing respiratory disease for a current dual user (e-cigarette and all combustible tobacco) were 3.30 compared with a never smoker who never used e-cigarettes. Analysis controlling for cigarette smoking alone yielded similar results.
Conclusions: Use of e-cigarettes is an independent risk factor for respiratory disease in addition to combustible tobacco smoking. Dual use, the most common use pattern, is riskier than using either product alone.
Authors
Dharma N Bhatta, Stanton A Glantz
[link url="https://www.scientificamerican.com/article/vaping-may-increase-the-risk-of-chronic-respiratory-disease/"]Scientific American report[/link]
[link url="https://www.ajpmonline.org/article/S0749-3797(19)30391-5/fulltext"]American Journal of Preventative Medicine abstract[/link]