The new study suggests cherry flavoring delivers more harmful quantities of benzaldehyde, which is a respiratory irritant.
The new study appears in Thorax, a specialist journal published by the BMJ.
In the US, current estimates suggest that 12.6% of adults report using electronic cigarettes (e-cigarettes), and this number is on the rise.
Some studies have suggested that e-cigarettes present lower health risks to users than conventional tobacco cigarettes, because of the difference in toxic compounds between the two.
Meanwhile, others have warned of the negative health impacts of the devices. One such study recently linked e-cigarettes to cancer-related cell damage, for example.
E-cigarettes typically contain flavorings that are safe when used in food products. However, their potential harm upon inhalation has raised concern within the medical community.
One such component of flavorings used in e-cigarettes is benzaldehyde, which is regularly used in cosmetics and foods. Interestingly, it is a key ingredient in so-called natural fruit flavorings.
The compound, however, has been proven to irritate the airways in both animal and workplace exposure studies.
As such, the researchers wanted to investigate the levels of benzaldehyde that an e-cigarette user breathes in from flavored devices purchased online.
Benzaldehyde inhaled from e-cigs greater than conventional ones
To begin, the researchers categorized the 145 e-cigarettes they used in their study according to their labels. The groups were as follows: 40 berry/tropical fruit, 37 tobacco, 15 alcohol, 11 chocolate/sweet, 11 coffee/tea, 10 mint/menthol, 10 cherry and 11 "other."
Using an automatic smoking simulator, the team produced aerosol vapor in the quantity of 30 puffs from each e-cigarette. They did so in two series consisting of 15 puffs each with a 5-minute pause in between.
Next, the team measured the quantities of benzaldehyde and calculated a daily inhaled dose of the compound for each product. They used the estimation that an experienced e-cigarette vaper puffs on an e-cigarette 163 times per day.
The researchers then compared the inhaled e-cigarette dose with that of a conventional cigarette, as well as a hypothetical maximum permissible dose that healthy workers could be exposed to during an 8-hour shift.
Results showed that benzaldehyde was present in 108 out of the 145 e-cigarettes, and the highest levels were found in the cherry-flavored e-cigarettes. In detail, the team found yields of the compound that were 43 times higher in cherry e-cigs.
Furthermore, the benzaldehyde inhaled from 30 puffs of the e-cigarettes were typically greater than those from a normal cigarette.
The researchers do add, however, that the daily inhaled dose from cherry e-cigarettes was 70.3 μg, which is over 1,000 times lower than the permissible exposure limit dose for benzaldehyde concentrations in the workplace.
Although their findings are significant, the researchers do report some limitations to their study. For example, because they used a simulator, it may not reflect actual inhalation while smoking an e-cigarette.
However, their findings still point to risks linked with cherry e-cigs, and they note that "users of cherry-flavored products may inhale significantly higher doses of benzaldehyde compared with users of other flavored products."
They conclude their study by writing:
"Although e-cigarettes may be a promising harm reduction tool for smokers, the findings indicate that using these products could result in repeated inhalation of benzaldehyde, with long-term users risking regular exposure to the substance."
MNT recently reported on a study that suggested teen users of e-cigarettes are three times more likely to smoke standard cigarettes a year later.