Health advocates are encouraging President Donald Trump to move forward with a federal ban on thousands of flavors used in e-cigarettes.

Trump is meeting at the White House on Friday with medical experts, health advocates and industry representatives on the problem of underage vaping.

Electronic cigarette use by teenagers has surged, but federal authorities have not finalized a plan for regulating e-cigarettes. Trump says he’s at the meeting to listen. Health and Human Services Secretary Alex Azar calls regulating e-cigarettes “highly complex.”

Gary Reedy of the American Cancer Society told the president the federal government should remove all flavors, including mint and menthol.

Trump’s meeting comes as some states begin to take action in response to growing concern about the health effects of vaping products.