Electronic cigarettes, battery-powered devices that convert a solution of nicotine and other chemicals into a vapor that can be inhaled, or "vaped," have the potential to wean a vast number of smokers off cigarettes. […] The problem is, not enough smokers are switching to e-cigarettes, despite their relative safety – and understandably so. Smokers are barraged with news about inaccurate labeling, shoddy counterfeits and poorly made e-cigarettes that emit toxins and cancer-causing chemicals in vapor.
Source: wiktionary