Juul Labs, the dominant e-cigarette company, illegally marketed its vaping products as a safe alternative to traditional cigarettes, the Food and Drug Administration said on Monday, casting a deepening shadow over the safety of e-cigarette devices.

The agency issued a warning letter to Juul, saying that the company violated federal regulations because it had not received federal approval to promote and sell its vaping products as a healthier option.

The F.D.A.’s action dealt a setback to the company’s efforts to rebrand itself in the wake of public outrage over a surge in teenage vaping.

And it served as a reminder that the health effects of e-cigarettes are not established at a time when more than 400 people have been sickened by vaping-related illnesses. Five deaths have been linked to vaping and hundreds of people have been hospitalized. Public health investigators have yet to determine a specific cause, but they have cited the use of cannabis and nicotine vaping products as possibilities. No one product or company has been implicated.

The investigation into Juul’s practices preceded this summer’s spate of lung illnesses, and was prompted by concerns that the company’s marketing and sales practices targeted youths. It included a review of congressional testimony from Juul executives, consumers — students and parents — and antismoking activists.

“Regardless of where products like e-cigarettes fall on the continuum of tobacco product risk, the law is clear that, before marketing tobacco products for reduced risk, companies must demonstrate with scientific evidence that their specific product does in fact pose less risk or is less harmful,” said Dr. Ned Sharpless, the acting F.D.A. commissioner. “Juul has ignored the law and, very concerningly, has made some of these statements in school to our nation’s youth.”

The agency on Monday pointed to specific instances that it said violated restrictions on those health claims. It referred to a statement by Kevin Burns, the company’s chief executive, on the Juul website in which he said that the company’s vaping system was designed to “heat nicotine liquid and deliver smokers the satisfaction that they want without the combustion and harm associated with it.”

The letter also cited congressional testimony about appearances by company representatives at schools: A Juul representative spoke at a school presentation and told students that Juul “was much safer than cigarettes” and that Juul was “totally safe.”

The agency said its concerns were amplified by the increased use of vaping products, including Juul’s, by teenagers, and by evidence that teenagers were particularly vulnerable to nicotine addiction.

Juul has long said that it did not deliberately target teenagers. In a statement, Matt David, a company spokesman, said, “We are reviewing the letters and will fully cooperate.”

The high levels of nicotine in Juul products are of particular concern for their effects on the still-developing brains of a generation of teenagers and as a potential gateway drug that could reverse decades of a steep decline in smoking rates.

[Here’s what you should know about the lung illness linked to vaping.]

Research into the long-term effects of e-cigarettes is at an early stage, which is one of the reasons the F.D.A. is trying to restrict marketing assertions by Juul and other companies in the industry. The agency ordered the company to submit its plan to correct the issues outlined in the warning within 15 days.

When public health officials publicly released a report of the first possible vaping-related death on Aug. 30, the Centers for Disease Control and Prevention issued an extensive warning against vaping: “E-cigarette products should not be used by youth, young adults, pregnant women, as well as adults who do not currently use tobacco products. If you use e-cigarette products, monitor yourself for symptoms (e.g., cough, shortness of breath, chest pain) and promptly seek medical attention if you have concerns about your health.”

At the same time, authorities have singled out for concern vaping devices and liquids that are “off the street,” or have been modified or used in a way that the manufacturer did not intend.

Juul’s rise has been meteoric, culturally and financially. It had virtually no sales in 2015, but by 2018 it had a valuation of $16 billion. That is less than half of its current estimated valuation of $38 billion, making the company one of the most recent successful growth stories in Silicon Valley.

Whether the agency’s action will dent its sales remains unclear. The F.D.A. warned that if Juul did not comply with laws governing vaping devices, it could impose civil penalties or an injunction, or seize the company’s products.

The growing popularity of e-cigarettes has been paralleled by an evolving and unfinished regulatory framework. The core question facing regulators and public health experts has been whether the potential benefits of the new technology, such as the possibility that it can reduce smoking-related deaths, will outweigh risks, like those posed to youth.

Initially, the F.D.A. set a deadline of August 2018 for e-cigarette companies to submit evidence that their products would serve the public health. Then, when Dr. Scott Gottlieb became the F.D.A. commissioner, he pushed back the compliance date by four years, to August 2022.

Later, as research showed soaring use of e-cigarettes among teenagers, Dr. Gottlieb expressed concern that the risks were growing. At that point, the F.D.A. sent letters to Juul and other companies demanding that they change their marketing and warning that the agency had the power to pull them off the market. The F.D.A. also seized Juul marketing materials to investigate whether the company, the market leader in e-cigarettes, had deliberately courted young users through youth-oriented advertising and social media, including sexualized images.

Juul asserted that it would fully cooperate with the investigation and has continued to argue that its target audience has always been adult smokers. The company has pulled most flavored e-cigarettes off retail shelves and began a promotional campaign, including full-page newspaper ads and digital ads, discouraging teen use of the product.

At the same time, Juul engendered further criticism by selling 35 percent of the company to Altria, one of the leading cigarette companies and the very competitor that Juul’s founders swore to make obsolete. The union fueled criticism that Juul ultimately cared about profits at the complete expense of public health, an assertion Juul denied.

The regulatory situation took another significant turn in July, when a federal judge ruled that the F.D.A. must move up its deadline for requiring e-cigarette companies to submit the public health benefits of their products. The judge said such submissions must be made within 10 months, or by May 2020.

Particularly in light of the recent surge of illnesses, the issue is reaching the highest realm of politics. Late last week, Senator Richard J. Durbin, Democrat of Illinois, wrote a letter to President Trump urging him to replace Dr. Sharpless with someone who would be tougher on the e-cigarette issue.

(adsbygoogle = window.adsbygoogle || []).push({});
(adsbygoogle = window.adsbygoogle || []).push({});