Currently, there are about four million Americans who use use battery powered cigarettes, according to the Tobacco Vapor Electronic Cigarette Association. And for the past several years the e-cigarette craze has become increasingly popular because of its convenience. The battery-powered devices, however, may have negative effects for those who are around the person smoking. According a new study in the journal Nicotine and Tobacco Research, e-cigarette smoke exposes non smokers to significant amounds of nicotine through the air. The risks of second-hand nicotine remain unstudied, according to the study.

The study was conducted using three brands of e-cigarettes, and the researchers looked into what their smoke was releasing into the air. They found that the second-hand smoke had high concentrations of nicotine, but it did not contain other harmful chemicals. Scientists used a smoke machine to simulate the smoking of a cigarette, and measured the concentrations of nicotine and other compounds such as carbon monoxide. Five male participants were then asked to smoke both tobacco and e-cigarettes in a room that measured contaminant exposure. While the nicotine emissions were 10 times less in e-cigarettes versus regular tobacco, they still proved to be a significant source of second-hand exposure. But, unlike conventional cigarettes, carbon monoxide and other volatile compunds were not released.

The study backs of previous data gathered by the U.S. Food and Drug Administration (FDA). “The FDA report found nine contaminates versus the 11,000 contained in a tobacco cigarette, and noted that the level of toxicity was shown to be far lower than those of tobacco cigarettes,” ABC News reported. Nevertheless, long-term use could still pose a threat. Even though the threat of other chemical compounds is only present in a very limited fashion, inhaling nicotine may still pose health risks — we just don't know.

In a section of the study called "Unanswered Questions and Future Research," the authors call for a deeper analysis of whether secondhand nicotine inhalation could be harmful for at rish populations. "We found no publications on the cardiovascular effects of passive exposure to e-cigarette vapors or on the health effects of secondhand exposure to e-cigarette vapors among vulnerable population, including children, pregnant women, and people with cardiovascular conditions," the authors write.

The American Cancer Society (ACS) believes that inhaling anything but natural air has side effects, but the organization is not quite sure how harmful these effects will be in the future. “Studies have shown that e-cigarettes can cause short-term lung changes that are much like those caused by regular cigarettes," the ACS writes on it's website. "But long-term health effects are still unclear.”

Source: Sobczak A, Travers M, Czogala J, et al. Secondhand Exposure to Vapors From Electronic Cigarettes. Nicotine & Tobacco Research. 2013.