The morass of conflicting information about e-cigarettes and tobacco use grew deeper Monday, when the Centers for Disease Control and Prevention released a new study showing that adolescents who vape say they are much more likely to smoke conventional cigarettes.

The results show that 43.9 percent of sixth- through 12th-graders who had used e-cigarettes said they intended to light up conventional cigarettes over the next year, compared with 21.5 percent of youth who had never used the electronic nicotine delivery systems.

Overall, more than 263,000 adolescents who had never smoked before used e-cigarettes in 2013, up from 79,000 in 2011, the CDC reported in a study in the journal Nicotine and Tobacco Research. The data come from the agency's National Youth Tobacco Surveys for 2011-2013.

The study also showed that 21.9 percent of the youth who had never smoked traditional cigarettes intended to give them a try in the next year -- almost exactly the same proportion as the 21.5 percent who had never tried an e-cigarette -- and that, overall, the percentage of youths who reported an intention to smoke declined "significantly" in the 2013 survey.

While there is no doubt that smoking tobacco is one of the worst things you can do for your health, there is debate about whether e-cigarettes promote cigarette use or can help prevent it by offering people access to nicotine-laced vapor without the harmful chemicals in tobacco smoke. Others claim that e-cigaretttes may help wean smokers off tobacco, for the same reason. In April, the Food and Drug Administration announced plans to regulate e-cigarettes for the first time since they came to the United States in 2006.

This November, 2013 study in the Lancet, concluded that "E-cigarettes, with or without nicotine, were modestly effective at helping smokers to quit, with similar achievement of abstinence as with nicotine patches, and few adverse events." Sally Satel, a resident scholar at the American Enterprise Institute and a psychiatrist who specializes in addiction even argued here that promoting e-cigarettes should be a "public health priority," free of taxes and with easily accessible starter kits. Perhaps, she says, that will make a dent in the $130 billion we spend every year on medical costs related to smoking.

Just about everyone agrees these issues need more study.

The CDC is not interested in kids dipping their toes in those waters. "We are very concerned about nicotine use among our youth, regardless of whether it comes from conventional cigarettes, e-cigarettes or other tobacco products," Tim McAfee, director of the agency's Office on Smoking and Health, said in a news release that accompanied the study.

"The increasing number of young people who use e-cigarettes should be a concern for parents...since youth e-cigarette users were nearly twice as likely to have intentions to smoke conventional cigarettes," added Rebecca Bunnell, associate director of the same office and lead author of the study. (I'm waiting to talk with McAfee or Bunnell and will update this post when they get back to me. Update: Neither was available Monday, and we have moved on to other matters.).

With tobacco and e-cig companies marketing heavily to young people, and 80 percent of cigarette smokers starting the habit by age 18, the CDC considers intervening with this age group critical. "These findings highlight the importance of enhanced efforts to prevent all forms of tobacco use among youth, [as well as] e-cigarettes," the study concludes.