E-Cicgarettes may indeed help smokers quit, according to a new report from released by the National Academy of Sciences (NAS), but at the same time the devices may pose a real threat of nicotine addiction -- and, possibly even a gateway to cigarette use -- for teens and young adults.

According to the NAS report, which looked at the body of evidence on these devices so far, e-cigarettes are a far better alternative to conventional smoking, and can help smokers quit.

But young adults who start using e-cigs may be more likely to take up conventional smoking in the future, the NAS warned.

Plus, he said, the studies the committee reviewed indicated that young adults using these products had a higher risk of smoking cigarettes at some point -- though the picture was not as clear when it came to whether their risks of becoming a lifelong smoker were higher if they used e-cigarettes.

The NAS report also notes that e-cigarettes contain fewer toxins than conventional cigarettes, but also that they likely contain a similar amount of nicotine, though this can vary depending on type of e-cigarette device used.