(Reuters) — The Food and Drug Administration on Thursday blocked e-cigarette maker Juul Labs Inc from selling its nicotine products in the United States, potentially dealing a fatal blow to the once high-flying San Francisco company.

Following a nearly two-year-long review of scientific and public health data submitted by the company, the FDA said the applications “lacked sufficient evidence” regarding the toxicological profile of the products to demonstrate that marketing them would be appropriate for the protection of public health.

Juul, along with other e-cigarette brands including British American Tobacco Plc’s BATS.L Vuse and Imperial Brands Plc’s IMB.L Blu, had to meet a September 2020 deadline to file applications to the FDA showing that its products provided a net benefit to public health.

The agency had to judge whether each product was effective in getting smokers to quit and, if so, whether the benefits to smokers outweighed the potential health damage to new e-cigarette users – including teenagers – who never smoked.

“We recognize these make up a significant part of the available products and many have played a disproportionate role in the rise in youth vaping,” FDA Commissioner Robert Califf said in a statement on Thursday.

Juul did not immediately respond to a Reuters request for comment.

Juul and other e-cigarette makers have been selling products in the United States for years without being officially authorized by the FDA, as regulators have repeatedly delayed deadlines for e-cigarette companies to comply with federal guidelines.

Teenage use of e-cigarettes surged with the rise in popularity of Juul in 2017 and 2018.

E-cigarette use among high school students grew from 11.7% in 2017 to 27.5% in 2019, before falling back to 11.3% in 2021, according to a federal survey.

Attorney James Frantz represents over 750 school districts and has been fighting Juul legally in court since 2019.

“Right now, they’re ecstatic that the FDA has stepped in and done something they should have done a couple of years ago,” Frantz said. “We have 768 school districts across the United States and 34 states, which is about 50,000 schools, and about 2 million students that attend those schools. And they are extremely happy with the ruling.”

Researchers who conducted the survey for the U.S. Centers for Disease Control and Prevention said the most recent youth e-cigarette data cannot be compared to earlier years because of changes in how the survey was conducted during the COVID-19 pandemic.

In 2020, the FDA banned all flavors except tobacco and menthol for cartridge-based e-cigarettes such as Juul. The company had pulled all other flavors including mint and mango in late 2019, following regulatory scrutiny and an outcry from anti-smoking advocates.

The Biden administration has been looking at other ways to help people quit smoking in an effort to cut down on preventable cancer deaths. It said this week it plans to propose a rule establishing a maximum nicotine level in cigarettes and other finished tobacco products to make them less addictive. 

Altria Group Inc MO.N, which has a 35% stake in Juul, closed down 9% on Wednesday after the Wall Street Journal first reported, citing people familiar with the matter, the FDA was preparing to order Juul to take its e-cigarettes off the market.