Updated 5:45 a.m. ETChocolate cupcake, creme, mango, tutti frutti, "blue" — sugary-sounding flavors familiar to teenage e-cigarette users are facing more crackdowns from the Food and Drug Administration.The FDA seized more than 1,000 pages of documents during a "surprise inspection" at JUUL Labs, an electronic cigarette company based in San Francisco. The agency has been narrowing their focus on JUUL and what critics say are its "kid-friendly flavors" as youth vaping rates have increased. In a statement to NPR, an agency spokesperson said Tuesday's surprise inspection was part of an effort to seek "further documentation related to JUUL's sales and marketing practices.""The inspection followed the Agency's request for information that we issued to JUUL Labs in April for documents that would help us to better understand the reportedly high rates of youth use and the youth appeal of JUUL products, including documents related to marketing and product design," the spokesperson said. The FDA's action came on the same day as new data from the CDC indicating that JUUL's sales grew more than seven-fold from 2016 to 2017.JUULs are trendy, USB-shaped vaporizers that provide a quick dose of nicotine to users. Introduced in 2015, the vapes are marketed as an alternative to tobacco cigarettes for adult users, but some critics say that flavors such as mango and creme appeal primarily to teenagers and children. One study suggests that 81 percent of childrenwho ever use tobacco start with a flavored tobacco product."The popularity of JUUL among kids threatens our progress in reducing youth e-cigarette use," said Dr. Robert Redfield, director of CDC, in a press release. "We are alarmed that these new high nicotine content e-cigarettes, marketed and sold in kid-friendly flavors, are so appealing to our nation's young people."The seizure was the latest in a series of FDA crackdowns on the e-cigarette market. In September, the agency announced it had issued more than 1,300 warning letters and fines to convenience stores, gas stations and other stores over the summer for selling e-cigarettes to minors — its largest such action to date.The FDA also sent letters that month to JUUL, Vuse, blue e-cigs, MarkTen and Logic — five companies that represent over 95 percent of the market — last month, giving them 60 days to submit plans on addressing widespread use of their products by minors. The agency alleges that much of that widespread use stems from flavored products. If the companies fail to do so, or submit plans deemed unsatisfactory, the FDA says they will consider removing "some or all of their flavored products that may be contributing to the rise in youth use from the market until they receive premarket authorization and otherwise meet all of their obligations under the law."On Tuesday, Sens. Richard Durban, D-Ill., and Lisa Murkowski, R-Alaska, asked the FDA to ban "fruit, candy and other kid-friendly" flavors. "It is abundantly clear that tobacco companies are developing and marketing e-cigarette flavors that appeal to, and addict, children," the senators wrote in a letter. Durban and Murkowski recently introduced legislation that would ban the use of flavoring in cigars — not e-cigarettes — and give tobacco companies one year to prove that "their e-cigarette flavors actually help adults quit smoking cigarettes" and "do no cause children to start smoking." Currently, there is no legislation regulating the flavors of e-cigarette products.FDA Commissioner Scott Gottlieb called youth e-cigarette use an "epidemic" last month, saying the practice "shows no signs of abating." "The FDA won't tolerate a whole generation of young people becoming addicted to nicotine," he continued. Copyright 2018 NPR. To see more, visit http://www.npr.org/.