Other chemicals in e-cigarettes are also raising alarms, including a few of the flavoring agents. “Most of the flavors are taken from the food industry and have been tested for safety when we eat them,” says Maciej L. Goniewicz, a professor of oncology at Roswell Park Cancer Institute, in Buffalo. “We don’t know what the health effects are when these flavors are inhaled,” he says. It will be difficult to test all of the thousands of different combinations of flavors that are on the market. “Some of the flavors are just a single compound, but many are mixtures of different chemicals,” Goniewicz points out.
Preliminary evidence suggests at least some flavors pose cause for concern. A group of researchers led by cardiologist Konstantinos E. Farsalinos of the Onassis Cardiac Surgery Center, in Greece, evaluated 159 samples of sweet-flavored e-juice, purchased from 36 manufacturers in seven countries, for the presence of the creamy buttery flavorings diacetyl and acetyl propionyl. The two chemicals have been approved for food use but are associated with respiratory disease when inhaled. The researchers found both chemicals in 74.2% of the samples (Nicotine Tob. Res. 2014, DOI: 10.1093/ntr/ntu176). They detected the chemicals in both the e-juice and the aerosol generated by heating the liquid.
Another flavor to watch out for is cinnamon, warns Prue Talbot, a professor of cell biology at the University of California, Riverside. Talbot and colleagues exposed human embryonic stem cells and human adult pulmonary fibroblasts to 36 different e-juices. Cinnamon Ceylon was the most cytotoxic, she says.
The researchers determined that both cinnamaldehyde and 2-methoxycinnamaldehyde are cytotoxic (Toxicol. in Vitro 2014, DOI: 10.1016/j.tiv.2013.10.006). They quantified the amount of each chemical in the fluids by using high-performance liquid chromatography and found that cytotoxicity correlated with the amount of cinnamaldehyde in the product. The amount of 2-methoxycinnamaldehyde varied in the fluids, even in separate samples of the same product. The results suggest that the cinnamon flavorings in e-cigarette refill fluids could adversely affect users, Talbot says.
Right now it’s a “user beware” market for e-cigarettes, Talbot emphasizes. There are no regulations on manufacturing the devices or the flavored e-juices, and scientists who are evaluating the products are seeing wide variation in the quality and performance of the products. Research being conducted today may ultimately be used to inform regulations to make e-cigarettes safer, but Talbot and many other experts predict it may take a long time before such regulations are in place.
In the meantime, Bixby and other vaping advocates are working hard to create a vaping community and culture that is more accepted by society than tobacco smoking. Bixby holds classes two nights a week at the DC Vape Joint to teach people how to use the latest vaping gadgets and, for more experienced vapers, how to build their own devices. He’s proud to have recently celebrated his two-year “vapeversary”—meaning it’s been two years since he quit smoking cigarettes and switched to vaping. He’s not in the vaping business for the money, he tells C&EN. His goal is to help people quit smoking.
The burning question, though, is whether vaping will be proven to be any less harmful than smoking.