F.D.A. Juul and e-cigarette retailers collapse

In April, the F.D.A. announced that it was investigating Juul's business practices to determine whether the company was deliberately targeting youth. The agency has requested tons of documents from the company, including focus group reports and toxicological studies. Juul submitted thousands of pages of documents to the agency, but neither the F.D.A. neither Juul made them public. Dr. Gottlieb said the agency's tobacco division was still monitoring them.

While the actions against the industry are alarming for the electronic cigarette companies, they are also problematic for F.D.A.

In July 2017, as part of a comprehensive plan to reduce tobacco-related deaths in the United States, the F.D.A. extended the deadline for e-cigarette manufacturers to comply with new stringent federal guidelines, which, among other things, require companies to prove that e-cigarettes are good for public health. Granting an extension of five years until 2022, Dr. Gottlieb said it would also require manufacturers to reduce nicotine levels in traditional cigarettes to make them non-addictive. For this to work, he said, smokers needed more and better substitutes for cigarettes.

But in an interview, Dr. Gottlieb said that the huge popularity of teenage vaping and increasing youth addiction had not been considered last summer and that the agency needed to rethink its policy – maybe approval to stay on the shelves.

Risa Robinson, professor of mechanical engineering at the Rochester Institute of Technology, began studying e-cigarettes six years ago for the F.D.A. The first products did not have enough nicotine to cause concern, she said. But later products, like Juul, have had more nicotine and, according to her, can become even stronger depending on how a user blows.

"I am very concerned now," said Dr. Robinson. Beyond nicotine, the addition of heat to electronic liquid flavors generates chemicals that have not yet been studied in depth, she added.

Massachusetts Attorney General Maura Healey, who recently opened an investigation into the marketing and sale of electronic cigarettes to minors, praised F.D.A.