New findings about the flavorings used in e-cigarettes continue to raise questions about the safety of currently used products and what kinds of regulation might be appropriate to apply to the industry. An investigation of two disposable-cartridge brands – BLU and NJOY – and half a dozen different brands of e-cigarette flavors found high levels of flavoring chemicals in the liquids, according to the study published yesterday in the journal Tobacco Control.
The researchers only analyzed the liquids themselves and did not explore possible health effects in e-cigarette users, or vapers, so the study can only raise questions. The challenge with studying the safety or possible harms of e-cigarettes is that many of the potential health concerns would show up over the long-term rather than the short-term, and e-cigarettes simply haven't been around and used widely for long enough to determine what those might be.
"Obviously people haven't been using these cigarettes for 25 years, so there's no data to know what the consequences are from long-term exposures," said senior study author James Pankow, a chemist at Portland State University in Oregon. "If you can't look at longitudinal data, you just have to look at what's in there and whether there things to be worried about."
In this study, the researchers measured the amount of flavor chemicals present in 30 e-cigarette fluids, including popular flavors such as bubble gum, cotton candy, chocolate, grape, apple, tobacco, menthol, vanilla, cherry and coffee. They found that the flavoring chemicals comprised anywhere from 1 to 4 percent of the e-cigarette liquids, equivalent to about 10 to 40 mg/mL.
The finding that raises questions about health effects, however, is that six of the 24 compounds used to flavor the liquids are part of a class of chemicals called aldehydes, known to be respiratory irritants. "The concentrations of some flavor chemicals in e-cigarette fluids are sufficiently high for inhalation exposure by vaping to be of toxicological concern," Pankow and co-authors wrote. That conclusion does not mean that these chemicals are definitely toxic at the doses found in the liquids. Rather, the researchers calculated what a typical person would be exposed to for each day of typical vaping (about 5 mL of liquid), and they determined that several brands would expose the vaper to levels of these chemicals that are well above workplace safety exposure limits. "For someone vaping, they could be getting a chronic exposure at twice the workplace limits," Pankow said.
The workplace limits are established for those working in candy manufacturing or factories for other edible products because e-cigarette companies are using the same food additives for these liquids that are found in many candies or other foods. These food flavorings are regulated by the FDA when added to foods – but there is no regulation of them in e-cigarettes. There aren't even labeling requirements for the added flavors as there are for required food product ingredient lists.
Further, as the Flavor Extracts Manufacturers Association (FEMA), has pointed out, the FDA standards for these flavor chemicals' use in foods are based on ingesting them, not inhaling them as happens with e-cigarettes. "Route of exposure is really important," Pankow said. "Your stomach is pretty good at tolerating a lot of terrible stuff."
For example, ingesting tiny amounts of formaldehyde – as all of us do when we eat fruits and vegetables – does not pose risks to us. Our body even makes formaldehyde that floats through our bloodstream and doesn't harm us. But inhaling formaldehyde, especially in substantial amounts over a long period of time, has been linked to several types of cancer. In fact, Pankow co-authored a study into the formaldehyde released from e-cigarettes that was published as a letter in the New England Journal of Medicine in January. That study did not identify concerning levels of formaldehyde at low-voltage settings of e-cigarettes, but it did find levels significantly higher than what would be in regular cigarettes on the high-voltage setting.
That study, co-authored by David Peyton, another chemist at Portland State University, also did not and could not conclude that e-cigarettes were "unsafe." Rather, like this one, it raised questions about regulation. "It's unfortunate that it's called vaping, which implies vapor, which implies water," Peyton told me when I interviewed him about that study in January. The liquid in e-cigarettes is a far cry from water, and we simply don't know what possible long-term effects might exist. "In the meantime, I think it's a mistake to presume safety," Peyton said then. "Yes, it's less dangerous than some other things, but to assume safe is also probably not the correct thing."
Peyton was not involved with this study into flavoring chemicals, but he suggested there are reasons to consider regulating these chemicals in e-cigarette fluids. A popular flavoring chemical for cherry and bubble gum flavors, for example, is benzaldehyde. The National Library of Medicine has identified a wide range of negative health effects from benzaldehyde, depending on the dosage. These include allergic reactions, skin inflammation, respiratory failure, and irritation to the eye, nose and throat.
"To put it simply, If I were vaping, I’d want to know the ingredients," Peyton said. "And make no mistake, these ingredients have not been certified as safe for inhalation, so arguments related to cooking and eating are not relevant."
