In the United States, a team of researchers from Penn State University analyzed the levels of free radicals produced by 49 flavored e-liquids in commerce. They then compared them to those of non-flavored liquids.
43% TESTED AROMAS HAVE HIGH PRODUCTION OF FREE RADICALS
Free radicals inhaled by e-cigarette consumers are toxins already linked to heart disease, cancer and other inflammations. The researchers found that 43% of the flavors tested were associated with higher production of free radicals.
By deepening their analyzes, the researchers also established that six chemical elements used to flavor e-liquids significantly increase the production of free radicals, including linalool, limonene and citral, which are used to give products a citrus scent. or flowery. Conversely, a handful of flavors including ethyl vanillin (used for vanilla flavoring) would decrease the production of free radicals.
To John Richie, a professor of public health sciences and pharmacology at the Penn State School of Medicine, these findings lead to a better understanding of the dangers of electronic cigarettes.
« When these products first hit the market, many people claimed that they were harmless, that it was only vapor. 
water“Richie recalls. " We know it was wrong but we had no figures to prove the dangerousness of e-cigarettes. Now we know that e-cigarettes do produce free radicals and the volume of these is affected by the addition of flavorings."
« It is important to examine the effects of these flavors on free radicals because e-cigarettes come in hundreds of flavors, some of which are aimed at a young clientele such as the bubble gum flavor."
Zachary Bitzer, who also collaborated in this study, adds that the flavors are not the same in all brands.
« Two different manufacturers may sell an 'orange scented' liquid but the two products may contain very different ingredients“, Explains Bitzer. " Coca and Pepsi are colas but the ingredients of these drinks are different. Similarly, e-liquids incorporate different flavoring agents, thus varying rates of free radicals"
Source : The Depeche / Free Radical Biology and Medicine
