E-cigarettes are dangerous and kids — lured by the fun flavors and advertising — need to steer clear of them, the nation's top doctor said Thursday.

The handheld devices deliver not only addictive and harmful nicotine, but can be loaded with toxic chemicals such as lead, diacetyl and nickel, U.S. Surgeon General Dr. Vivek Murthy said in a new report.

A man smoking an electronic cigarette. Yui Mok / PA Wire

“All Americans need to know that e-cigarettes are dangerous to youth and young adults,” Murthy said. “Any tobacco use, including e-cigarettes, is a health threat, particularly to young people.”

Related: E-Cigarettes Deliver Harmful Chemicals

E-cigarettes are now the most commonly used tobacco product among children, teens and young adults.

People who vape are also more likely to use conventional cigarettes and other tobacco products such as hookahs and snuff.

“Any tobacco use, including e-cigarettes, is a health threat, particularly to young people.”

Earlier this year, the Food and Drug Administration said it will ban their sale to anyone under 18. And the Centers for Disease Control and Prevention say e-cigarette makers directly and deliberately target kids in their advertising and marketing and in choosing appealing flavors.

Related: E-Cigarette Ads Target Kids, CDC Says

“The use of products containing nicotine poses dangers to youth, pregnant women and fetuses. The use of products containing nicotine in any form among youth, including e-cigarettes, is unsafe,” the report reads.

"Nicotine ... is highly addictive and has clear neurotoxic effects," Dr. Benard Dreyer, president of the American Academy of Pediatrics said at a news conference.

"E-cigarettes have the potential to addict the next generation and it's a major public health concern to us," Dreyer added.

But children, teens and young adults often think e-cigarettes are safe.

A salesman displays electronic cigarettes REGIS DUVIGNAU / Reuters file

“My friends and I believed e-cigarettes only released water vapor,” Tyra Nicolay of Shiprock, New Mexico, told the news conference.

Nicolay, a former vaper, said she enjoyed the candy flavors of vaping products.

“I’ve since learned that e-cigarettes are marketed in a way that appeal to kids,” Nicolay said, making them seem harmless.

Murthy told reporters that such confusion surrounding e-cigarettes remains widespread.

Related: What's So Bad About E-Cigarettes

“E-cigarettes went from being rare in 2010 to being the most common tobacco product used among our youth," he said. "It also threatens 50 years of hard-fought progress we made curbing tobacco use.”

"E-cigarettes have the potential to addict the next generation and it's a major public health concern to us."

The federal government's report notes that in 2015, one in 6 high school students used an e-cigarette in the past month.

“The report finds that, while nicotine is a highly addictive drug at any age, youth and young adults are uniquely vulnerable to the long-term consequences of exposing the brain to nicotine, and concludes that youth use of nicotine in any form is unsafe,” the Health and Human Services department said in a statement.

“The report also finds that secondhand aerosol that is exhaled into the air by e-cigarette users can expose others to potentially harmful chemicals.”

Related: FDA Proposes Limiting E-Cigarettes for Kids

But some reports have found that e-cigarettes can help smokers quit.

"E-cigarettes could benefit public health if they are found to be effective at helping smokers quit completely, properly regulated and responsibly marketed to adult smokers. However, the evidence to date is limited and inconclusive as to whether e-cigarettes are effective at helping smokers qui," said Matthew Myers, president of the Campaign for Tobacco-Free Kids.

Murthy said more high quality studies are needed before that becomes accepted, and said in the meantime, more needs to be done to help stop kids from taking up the vaping habit.

“We need parents, teachers, health care providers and other influencers to help make it clear that e-cigarettes contain harmful chemicals and are not OK for kids to use,” Murthy said. “Today’s report gives them the facts about how these products can be harmful to young people’s health.”