People standing near someone using an e-cigarette will be exposed to nicotine, but not to other chemicals found in tobacco cigarette smoke, according to a new study.
E-cigarettes, or electronic cigarettes, create a nicotine-rich vapor that can be inhaled, or 'vaped.'
Researchers and regulators have questioned whether e-cigarettes are a smoking cessation aid or may lure more young people toward smoking, as well as what effects they have on health.
"There is ongoing public debate whether e-cigarettes should be allowed or prohibited in public spaces," study co-author Maciej Goniewicz told Reuters Health in an email.
Goniewicz is a cancer researcher in the Department of Health Behavior at the Roswell Park Cancer Institute in Buffalo, New York.
"E-cigarettes contain variable amounts of nicotine and some traces of toxicants. But very little is known to what extent non-users can be exposed to nicotine and other chemicals in situations when they are present in the same room with users of e-cigarettes," Goniewicz said.
He and his colleagues conducted two studies of secondhand exposure to e-cigarette vapors in a laboratory. Their results were published in Nicotine and Tobacco Research.
In the first study, the researchers used an electronic smoking machine to generate vapor in an enclosed space. They measured the amount of nicotine as well as carbon monoxide and other potentially harmful gases and particles in the chamber.
The second study included five men who regularly smoked both tobacco cigarettes and e-cigarettes. Each man entered a room and smoked his usual brand of e-cigarette for two five-minute intervals over an hour while the researchers measured air quality. The room was cleaned and ventilated and the experiment was repeated with tobacco cigarettes.
The researchers measured nicotine levels of 2.5 micrograms per cubic meter of air in the first study. Nicotine levels from e-cigarettes in the second study were slightly higher at about 3.3 micrograms per cubic meter. But tobacco cigarette smoking resulted in nicotine levels ten times higher at almost 32 micrograms per cubic meter.
"The exposure to nicotine is lower when compared to exposure from tobacco smoke. And we also know that nicotine is relatively safer when compared to other dangerous toxicants in tobacco smoke," Goniewicz said.
E-cigarettes also produced some particulate matter, but regular cigarettes produced about seven times more. E-cigarettes didn't change the amount of carbon monoxide or other gases in the air.
"What we found is that non-users of e-cigarettes might be exposed to nicotine but not to many toxicants when they are in close proximity to e-cigarette users," said Goniewicz.
"It is currently very hard to predict what would be the health impact of such exposure," he added.
He said more research is needed to find out how the current findings correspond to "real-life" situations, when many people might be using e-cigarettes in a room with restricted ventilation.
"This is an interesting piece and points in the direction that a number of other studies are pointing, though it begins to expand the evidence on the potential effects to others," Amy Fairchild told Reuters Health in an email.
Fairchild was not involved in the new research, but has studied how e-cigarette use might impact views on regular cigarettes at the Columbia University Mailman School of Public Health in New York.
She said the study suggests e-cigarettes are far safer, both in terms of toxins and nicotine, than tobacco cigarettes when it comes to the health effects on bystanders - although more research is needed to know for sure.
"In locales considering extending smoking bans to e-cigarettes, I think that these data weaken the case for more sweeping bans," Fairchild said. "And so this begins to answer the question about why e-cigarettes are considered better: they reduce risks to both the user and to the bystander when compared to tobacco cigarettes."
Fairfield said the concern about vaping ultimately revolves around whether e-cigarettes are going to change broader patterns of smoking at the population level.
"There are potential harms, including promoting continued smoking of cigarettes and renormalizing cigarette smoking behaviors," Goniewicz said. "Regulatory agencies around the world will need to make a number of regulatory decisions about product safety that could have major effects on public health."
Goniewicz has received funding from a drug company that makes medications to aid smoking cessation. Another study author has received funds from an e-cigarette manufacturer.