More people in the United States are addicted to nicotine than any other drug, states the Centers for Disease Control and Prevention. Smokers become dependent on cigarettes for various reasons, not the least of which is the addictive properties of nicotine. 
According to longitudinal data from the National Population Health Survey in Canada, approximately 20 percent of adult daily smokers 18 years and older who had quit in the past two years resumed smoking within the next two years. The CDC says quitting smoking may require several attempts before quitters can successfully put smoking behind them. Factors such as withdrawal symptoms, stress and weight gain compel many people to light up after quitting. 
Some people may feel that e-cigarettes can help them gradually kick their tobacco habit. And thanks to the variety of flavors and styles of vapor-based nicotine delivery systems, it seems more people are vaping because they believe it to be less dangerous than traditional smoking. But the Center for Tobacco Control Research and Education at the University of California indicates smokers who vape are 28 percent less likely to ditch traditional cigarettes despite believing they are cessation aids. And they still may be putting their health in grave risk. The American Lung Association says there are hundreds of brands of e-cigarettes on the market and none of them have been evaluated by the FDA for safety. 
Because vaping is largely in its infancy, there are no long-term studies of its health implications or its efficacy in regard to helping smokers quit. However, much of the available evidence suggests that vaping may only be marginally better than using tobacco cigarettes. Analysis from the Society for Research on Nicotine and Tobacco suggests that people who vape every day may double their risk of having a heart attack than those who do not vape or smoke (compared to triple the risk with smoking tobacco). Also, according to the Bloomberg School of Public Health, researchers found that the aerosol particles that vapers breathe contain some of the same toxic metals and metallic elements found in conventional cigarettes, including cadmium and nickel. Potentially unsafe levels of several other dangerous substances, such as arsenic, chromium and manganese, were also found.
Another cause for concern is the propensity to abuse e-cigarettes, toking much more than is recommended. Vapers may be consuming very high levels of nicotine per day without realizing how much they are inhaling. A 2014 study showed wide-ranging nicotine levels and inconsistencies between listed and actual nicotine levels, according to the ALA.
E-cigarettes are a controversial subject. More research is required to determine their health risks and their potential to help people quit smoking altogether.