Shutterstock The US Food and Drug Administration is beginning to crack down on a wildly popular vape pen called the Juul, which contains twice the nicotine of comparable devices. A growing list of experts worry the Juul targets young people, whose brains are especially vulnerable to nicotine and addiction. In a statement on Tuesday, FDA commissioner Scott Gottlieb called out the Juul and said the agency would "not tolerate the sale of any tobacco products to youth." It looks like a USB drive, comes in colors like fire-engine red and bright turquoise, and is available in flavors like creme brûlée and cool mint. The Juul (pronounced "jewel") appears to have a loyal and growing following among young people, who brag on social media about sneaking puffs in classrooms or school bathrooms.See the rest of the story at Business InsiderNOW WATCH: Animated map of Mars reveals where humans should build the first Martian citiesSee Also:There's a new vape pen taking over America — and it has Wall Street worried about tobacco stocksWhat marijuana really does to your body and brainWhat marijuana does to your body and brainSEE ALSO: There's a new vape pen taking over America — and it has Wall Street worried about tobacco stocks DON'T MISS: A vape pen with twice the nicotine of comparable devices is taking over high schools — and adults are frightened