On a recent afternoon in Seattle’s University District, a steady stream of customers—mostly young men—filtered in and out of a small, recently opened shop called E Cig ’N Vape. It’s one of a chain of six Washington state stores that sells supplies for smoking electronic cigarettes, or e-cigarettes. The battery-powered devices deliver an inhalable vapor, with or without nicotine, in a variety of flavors.
Pete Knutson, a 32-year-old University of Washington student who works at the shop, told a customer about some of the 60 flavors of e-liquid, or e-juice, the store offers. Key lime pie “tastes like key lime going out with a kind of a graham cracker crust,” he said; black honey tobacco, one of the most popular flavors, is “nice and earthy. It’s good for people who are transitioning from smoking—they don’t quite like fruit, but they don’t want to taste tobacco.”
In addition to flavoring agents, the e-liquids contain an aqueous solution of glycerol or propylene glycol, which turns into an opaque vapor when heated. E-liquids come in five different levels of nicotine, ranging from 0 mg to 24 mg in 1 mL of juice.
Similar to about 90% of the store’s customers, Knutson smoked tobacco cigarettes for years before switching to smoking e-cigarettes—often called vaping—two years ago. Taking a drag from a reusable e-cigarette, he let out a cloud of a flavor called hypnotic. It smelled like cotton candy.
Nathan Pierce, a 19-year-old customer who attends North Seattle Community College, sat in a chair and puffed on his e-cigarette. Pierce had smoked tobacco occasionally, enjoying the nicotine buzz but not how it made him feel and smell afterward. So he bought a reusable e-cigarette a month and a half ago. “It’s nice to be able to enjoy different flavors and choose how much nicotine I’m putting in my body,” he said.
E-cigarette use is on the rise in the U.S., with projected sales of $1.5 billion in 2014. Like Knutson, many start using the devices because they seem like a safer alternative to tobacco cigarettes, with the added draw that they can still be enjoyed in public in many places. Some also use them to aid in quitting smoking by reducing their nicotine intake.
This growth in use has also fueled a debate over the health risks of e-cigarettes. Some researchers project that a widespread switch to the devices by current smokers could reduce the number of smoking-related deaths. But they and others also worry about e-cigarettes’ acute and secondhand health risks, as well as a lack of regulation of the devices. Additionally, some public health advocates say that e-cigarettes pose a risk of remystifying smoking, a habit that has been on the decline in the U.S. since the 1960s.
Because of these concerns, several states and more than 100 counties and cities in the U.S., including New York City and Chicago, have banned the use of e-cigarettes in spaces where tobacco smoking is prohibited. Many other states prohibit their use in specific locales such as schools, workplaces, and corrections facilities. In 2011, the Food & Drug Administration announced its intention to regulate e-cigarettes as tobacco products; the agency’s proposed plan is anticipated soon.
Compared with tobacco products, e-cigarettes are a safer option for smokers; they don’t deliver many of the harmful by-products of tobacco combustion, says Maciej L. Goniewicz, a toxicologist at Roswell Park Cancer Institute, in Buffalo. Nicotine is addictive and can increase heart rate, but it poses lower risk than the carcinogenic compounds in tobacco smoke, he says. The glycerol and propylene glycol in e-liquid are generally recognized as safe by FDA.
“But there’s no reason for experimenting with this product if you’re not already smoking tobacco cigarettes,” he adds. Little research has been done on e-cigarettes’ acute health risks, and their danger, especially for long-term use, is unknown. As the devices are unregulated, the quality control of the more than 250 brands currently on the market is uncertain.
To look inside, Goniewicz and colleagues recently enlisted a robotic smoking machine to take puffs of 12 different brands of e-cigarettes. Using chromatography and mass spectrometry, the team analyzed four types of potentially harmful compounds in the vapor (Tob. Control 2014, DOI: 10.1136/tobaccocontrol-2012-050859).
The researchers found small amounts of six toxic substances that are also found in tobacco cigarette smoke at 9 to 450 times as great a level as what is found in e-cigarette vapor. The substances include three carbonyl compounds: formaldehyde, a carcinogen, as well as acetaldehyde and acrolein. The team also found the volatile organic compound toluene and traces of two carcinogenic nitrosamines.
Additionally, they found small amounts of cadmium, nickel, and lead in the vapor—less than 1 µg per 150 puffs—that are also present in tobacco cigarette smoke. Another research team has also found metal particles in e-cigarette vapor (PLoS One 2013, DOI: 0.1371/journal.pone.0057987).
Inhaling particles containing metals and other compounds can trigger lung and throat inflammation. But predicting the risks for the average e-cigarette user is challenging, Goniewicz notes, because e-cigarette design variation and how deeply a user inhales affect exposure. According to Goniewicz, the larger, unanswered question is, “What will happen after many years of vaping? To see some of the long-term effects we just need time.”
Bystanders are exposed to nicotine when others vape near them but not necessarily to other toxicants found in e-cigarette vapor, Goniewicz and other groups have found (Nicotine Tob. Res. 2013, DOI: 10.1093/ntr/ntt203 ). Nicotine from the vapor is also deposited on surfaces, according to data the group presented at last month’s meeting of the Society for Research on Nicotine & Tobacco. Nicotine residue can react with other compounds in air to form carcinogenic nitrosamines. “Parents using e-cigarettes around small kids should be aware of these findings,” Goniewicz says.
To address these risks, Stanton A. Glantz, a medical researcher at the University of California, San Francisco, thinks communities should integrate bans on e-cigarettes into clean indoor air legislation. He adds that smoke-free environments are a strong incentive to help people quit smoking.
Glantz is also troubled by evidence that minors are adopting e-cigarettes, potentially leading to nicotine addiction and tobacco use. The proportion of U.S. high school students who said they had tried e-cigarettes more than doubled from 2011 to 2012, a jump from 4.7% to 10%, according to a survey by the Centers for Disease Control & Prevention. About 76% of middle and high school students who said they used them in the past month had also used tobacco within the same period. So far, at least nine states have outlawed the sale of the devices to minors.
Both Glantz and Goniewicz say FDA should adopt quality-control standards for e-cigarettes to protect consumers. Glantz also thinks the agency should crack down on claims by e-cigarette companies that the devices help users quit smoking because this has not been conclusively demonstrated. FDA-approved nicotine replacement therapies, including patches, gum, and inhalers, are options with proven track records.
Back at E Cig ’N Vape, Pierce said he tries to keep up on new information about the health risks of e-cigarettes. Knutson thinks switching to them has been better for both his health and his budget. “Two years ago, I wouldn’t have been able to walk up the hill over there,” he said, pointing out into the rain. “Now I can jog up it.”
“We see some potential for smokers and some dangers, including experimentation among kids,” Goniewicz notes. “FDA must look at the whole public health impact of the product.”