American President Donald Trump says his administration will propose banning thousands of flavors of electronic cigarettes, known as e-cigarettes.

　　The Food and Drug Administration (FDA) will develop rules to remove all e-cigarette flavors, except tobacco, from the U.S. market.

　　Health and Human Services Secretary Alex Azar made the announcement Wednesday. He spoke at the White House during an appearance with the president, first lady Melania Trump and the acting chief of the Food and Drug Administration (FDA), Ned Sharpless.

　　E-cigarettes are a popular substitute for traditional smoking products. They have been available in the United States for more than 10 years.

　　The electronic devices heat liquid into vapor -- very small particles that users inhale. Many users vape with a liquid that includes flavoring, nicotine and other chemicals. Nicotine is a natural chemical found in tobacco plants.

　　Trump said vaping has become such a problem that he wants parents to be informed of what is happening.

　　"People are going to watch what we're saying and parents are going to be a lot tougher with respect to their children," Trump said.

　　It will take several weeks to develop the proposed flavor restrictions.

　　Trump's first public comments on vaping come as U.S. officials investigate hundreds of breathing problems in people who have used e-cigarettes and other vaping devices.

　　No single device, ingredient or additive has been identified, although many cases involve marijuana vaping devices. There is still little research on the long-term effects of vaping.

　　The administration proposal would only affect nicotine vaping products, which are subject to FDA rules.

　　The FDA has had the power to ban vaping flavors since 2016, but up until now resisted calls to take that step. Agency officials instead said they were studying whether flavors could help people stop smoking traditional cigarettes.

　　But many parents, politicians and health activists have called for action on flavors. They argue that flavoring is largely to blame for a rise in vaping among U.S. teenagers.

　　"We simply have to remove these attractive flavored products from the marketplace until they can secure FDA approval, if they can," Azar said. He added that flavored products could seek the agency's permission to re-enter the market.

　　Azar said the administration would let tobacco-flavored e-cigarettes remain available for adults. But he said that if children begin using those products, "we will take enforcement action there also."

　　A 2009 law banned all flavors from traditional cigarettes except menthol. But that law did not affect e-cigarettes, which were then a small percentage of the tobacco market.

　　A ban on flavors would represent a huge blow to the vaping industry. Juul, one of the best known manufacturers, has grown into a huge business by selling mint, fruit and dessert flavored-nicotine products.

　　Juul and other vaping companies argue that their products are supposed to help adult smokers reduce their dependence on traditional paper-and-tobacco cigarettes. But there is little evidence that e-cigarettes are effective for helping people stop smoking.

　　Federal law bars e-cigarette and all other tobacco sales to those under age 18. But last year, one study found that 1 in 5 high school students reported vaping in the past month. Government health officials have called the rising in vaping an "epidemic."

　　More than 80 percent of underage teens who use e-cigarettes say they chose the product because it "comes in flavors that I like," studies have found.

　　I'm Ashley Thompson.

　　George Grow adapted this story for VOA Learning English based on a report by The Associated Press. Ashley Thompson was the editor.

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