BOSTON, U.S.: Cigarette smoke contains microbes and microbial toxins, such as endotoxin and glucan, that may have adverse respiratory effects. However, the potential for contamination of e-cigarette products sold in the U.S. has not yet been investigated. A new study aimed to fill that gap and reported that e-cigarette products sold in the U.S. are contaminated with bacterial and fungal toxins and therefore may pose serious respiratory health risks.
Researchers from the Harvard T.H. Chan School of Public Health (Harvard Chan School) examined 75 popular e-cigarette products. They classified the products into four flavor categories—tobacco, menthol, fruit and other—and then screened them for the presence of endotoxin and glucan.
The findings showed that 17 products contained detectable concentrations of endotoxin, whereas 61 products contained detectable concentrations of glucan. Further analysis revealed that cartridge samples had 3.2 times higher concentrations of glucan than the e-liquid samples. Glucan concentrations were also significantly higher in tobacco- and menthol-flavored products, compared with fruit-flavored products. However, fruit-flavored products were higher in endotoxin concentrations, which indicates that raw materials used in the production of flavors might be a source of microbial contamination, according to the research team.
“Airborne Gram-negative bacterial endotoxin and fungal-derived glucans have been shown to cause acute and chronic respiratory effects in occupational and environmental settings,” said senior author Dr. David Christiani, Elkan Blout Professor of Environmental Genetics at the school. “Finding these toxins in e-cigarette products adds to the growing concerns about the potential for adverse respiratory effects in users.” Previous research from the Harvard Chan School has shown that chemicals linked with severe respiratory disease are found in common e-cigarette flavors.
The researchers noted that the contamination may occur at any point during the production of the ingredients or of the finished e-cigarette product. According to them, the cotton wicks used in e-cigarette cartridges may be one source of contamination, as both endotoxin and glucan are known contaminants of cotton fibers. “In addition to inhaling harmful chemicals, e-cig users could also be exposed to biological contaminants like endotoxin and glucan,” said lead author Dr. Mi-Sun Lee, a research fellow at the school. “These new findings should be considered when developing regulatory policies for e-cigarettes,” Lee concluded.
According to the Centers for Disease Control and Prevention, e-cigarette use among American high school students increased by 78 percent between 2017 and 2018, and by 48 percent among middle schoolers.
The study, titled “Endotoxin and (1→3)-β-D-glucan contamination in electronic cigarette products sold in the United States,” was published online in the April 2019 issue of Environmental Health Perspectives.