A recent study found that popular e-cigarette products sold in the US were contaminated with bacterial and fungal contaminants, Science Daily reported.

The research conducted by Harvard T.H. Chan School of Public Health examined 75 popular e-cigarette products, including cartridges (single use) and e-liquids (refillable material) found that 27 per cent were contaminated with traces of endotoxin, a microbial agent found on Gram-negative bacteria, and that 81 per cent contained traces of glucan, which is found in the cell walls of most fungi, according to the report. Exposure to these toxins has been linked to asthma, reduced lung function and inflammation in humans.
For the study, the researchers picked 37 e-cigarette cartridges, and 38 e-liquid products, which can be used to refill certain cartridges from the 10 most popular US brands. The products were classified into four flavour categories (tobacco, menthol, fruit and other) and then checked for endotoxin and glucan, Science Daily reported.
The study found that cartridges had 3.2 times higher concentrations of glucan than e-liquids and that glucan concentrations were also higher in tobacco- and menthol-flavoured products when compared with fruit flavoured products, according to the report. Further analysis found that endotoxin concentrations were more concentrated in fruit-flavoured products, which suggests that raw materials used in the production of flavours might be a source of microbial contamination.
The researchers mentioned that the contamination of the products could have happened at any point during the production of the ingredients or of the finished e-cigarette product, Science Daily reported. In addition to that, the researchers suggested that cotton wicks used in e-cigarette cartridges could be a possible source of contamination, whereas endotoxin and glucan are known contaminants of cotton fibres.
The study is published in Environmental Health Perspectives.