High levels of chemical flavourings in e-cigarettes could cause respiratory irritation, according to a study performed by researchers at Portland State University in the USA.
The study examined 30 different e-cigarette fluids and analysed the chemicals used to flavour them. They found that many of the flavourings used in e-cigarettes were classified as safe for eating but this does not necessarily mean that they are then safe to inhale. Substances could still be considered toxic through inhalation. The researchers found that in 13 of the products they tested, flavourings constituted more than 1% of the liquid, while seven had more than 2%. Two of the product's had over 3% flavouring. The researchers were concerned that these levels of flavouring could act as a respiratory irritant.
The researchers commented: 'The concentrations of some flavour chemicals in e-cigarette fluids are sufficiently high for inhalation exposure by vaping to be of toxicological concern. Regulatory limits should be contemplated ingredient identification, levels of some of the more worrisome chemicals, and total flavour chemical levels.'
Of particular concern were the compounds benzaldehyde and vanillin, which are known to irritate the respiratory system. The researchers discovered that, based on data on the usage of e-cigarettes, the average user inhales more than twice the recommended exposure limits of these chemicals.
While the products tested represent only a small fraction of the e-cigarette market, the researchers said: 'The results obtained are likely to be similar to what a broad survey would have revealed, and in any case strongly suggest that very high levels of some flavour chemicals are undoubtedly present in a great number of the thousands of products currently available.'