WASHINGTON, Feb. 28 (Xinhua) -- In 2011, about 21 percent of American adults who smoke traditional cigarettes used electronic cigarettes, also known as e-cigarettes, up from about 10 percent in 2010, according to a study released on Thursday by the U.S. Centers for Disease Control and Prevention (CDC).
Overall, about six percent of all U.S. adults have tried e- cigarettes, according to the study.
"E-cigarette use is growing rapidly," said CDC Director Tom Frieden in a statement. "There is still a lot we don't know about these products, including whether they will decrease or increase use of traditional cigarettes."
Although e-cigarettes appear to have far fewer of the toxins found in smoke compared to traditional cigarettes, the impact of e- cigarettes on long-term health must be studied, the CDC cautioned. Research is needed to assess how e-cigarette marketing could impact initiation and use of traditional cigarettes, particularly among young people, it added.