Harvard University researchers have discovered that many popular electronic cigarette (e-cigarette) products are contaminated with microbial toxins that are known to cause a range of health problems. The research was published today in the journal Environmental Health Perspectives.
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The authors warn that the findings indicate that “some popular [e-cigarette] brands and flavors may be contaminated with microbial toxins.”
The toxins identified were endotoxin − a potent toxic molecule found on the membranes of Gram-negative bacteria − and glucan, a polysaccharide that helps to form the cell walls of most species of fungi.
Tobacco smoke from traditional tobacco cigarettes also contains endotoxins and glucans that that contaminate the products at some point during the manufacturing process. Exposure to such toxins is associated with respiratory health problems such as asthma, reduced lung function, and lung inflammation. Furthermore, studies conducted over many decades have demonstrated chronic lung impairment in populations exposed to airborne biological contaminants.
Yet, according to the authors of the current study, no studies have ever explored whether these common microbial agents could also be present in e-cigarette products.
Acute and chronic respiratory effects
Now, Professor of Environmental Genetics, David Christiani, and colleagues have tested 75 popular products from ten leading e-cigarette brands, including 37 single-use cartridges (also called “cigalikes”) and 38 e-liquids (which are used to refill cartridges). All products were purchased online, with the exception of products from one brand, which was bought at a convenience store on the university’s campus.
The products were divided into four different flavors, which included tobacco, menthol, fruit, and other. All products were then tested for the presence of endotoxin and glucan.
As reported today in the journal Environmental Health Perspectives, the researchers found that 17 (23%) of the products contained detectable levels of endotoxin and that 61 (81%) contained traces of glucan.
Further analysis showed that, on average, the cartridges contained 3.2 times more glucan than the refillable e-liquid samples.
On average glucan levels were ten times higher in the tobacco and menthol-flavored products, compared with in the fruit-flavored samples, while endotoxin concentrations were found to be significantly higher in the fruit-flavored products.
Airborne Gram-negative bacterial endotoxin and fungal-derived glucans have been shown to cause acute and chronic respiratory effects in occupational and environmental settings. Finding these toxins in e-cigarette products adds to the growing concerns about the potential for adverse respiratory effects in users."
Contamination can occur at any stage in the manufacturing process
The authors suggest that the raw materials used to produce ‘fruity’ flavors are a potential source of microbial contamination.
They also note that contamination could be introduced at any stage during the manufacture of the e-cigarette ingredients or in the production of the finished e-cigarette products themselves. One potential source, for example, is the cotton wicks used in the cartridges, since both endotoxins and glucans are known to contaminate cotton fibers.
The use of e-cigarettes has gradually been in creasing over recent years, particularly among high-school age and middle-school age pupils. Estimates suggest that last year, more than three million high school students used the products, a significant increase on the 220,000 students estimated to have used the products in 2011.
Mi-Sun Lee says the new findings should be considered when developing regulatory policies for e-cigarettes:
In addition to inhaling harmful chemicals, e-cig users could also be exposed to biological contaminants like endotoxin and glucan."
Mi-Sun Lee, Lead Author
Further research is needed
Lee and colleagues note that there are limitations to the study. For example, the team did not test the concertation of toxins that are aerosolized and passed on to the user.
Furthermore, the team only screened for toxins in first-generation devices and not more recently developed products such as tanks, pods or pens. Pods, especially, are known to deliver a higher concentration of nicotine per puff, compared with first-generation devices, yet scientists do not know how this may impact on the degree of exposure to toxins.
Many scientists believe that exposure to environmental toxins is significantly less among people who vape than among those who smoke traditional cigarettes, but that this does not necessarily mean that e-cigarettes products are not damaging to health at all.
Should the government ban e-cigarettes?
Currently, there is no scientific evidence that can conclusively support the hypothesis that the levels of endotoxin and glucan found in e-cigarette products is enough to raise public health concerns.
However, given that exposure to high enough levels of airborne endotoxin does appear to harm the lungs and that the toxins are thought to contribute to the damage that cigarette smoking has on respiratory health, the authors think that further study is needed.
Future research will look at how often the toxins are present in e-cigarette flavors and whether exposure to them through vaping poses and significant health risk, since there may be strategies that could be used to minimize the risk of contamination.