A mysterious lung illness that appears to be associated with vaping has swept across the country over the past few months, according to the Centers for Disease Control and Prevention. Most of the victims are young people, who have been admitted to hospitals with symptoms that can include severe shortness of breath, fever, vomiting and diarrhea. One patient in Illinois died. NBC News reports that data from state health departments indicate at least 329 people have been affected.

Many of the cases seem to involve vaped liquids that contain ingredients from cannabis, such as THC (marijuana's psychoactive compound) or the cannabidiol known as CBD. Last week, federal health authorities issued a warning specifically citing vaping products that contain THC or CBD.

Even if most of the lung-injury cases are traced to the oils and chemicals used to emulsify THC or CBD into illegal vaping "juices," that doesn't let legally sold, nicotine-based e-cigarettes off the hook. The troubled state of the industry could be seen on Wednesday when Michigan became the first state to ban flavored e-cigarettes, a step taken to protect young people from the potential harms of vaping, according to Gov. Gretchen Whitmer, a Democrat.

The established e-cig brands and the vape stores that mix legal e-liquids have been regulated by the Food and Drug Administration since summer 2017 (when I was the agency's commissioner) for their ingredients, marketing and labeling, among other features. Since putting this framework in place, the agency has conducted more than 1,000 inspections of these businesses.

But we also extended the deadline for e-cig manufacturers to apply for the agency's marketing authorization. We had two principal reasons: First, the rule giving the FDA authority to regulate e-cigarettes took six years to draft and finalize, and we were fully implementing it that summer. Guidance and regulations for how manufacturers should prepare applications (and how the FDA should review them) didn't exist. Time was needed to get that framework in place.

Second, we were simultaneously advancing new policies to prevent up to 8 million tobacco-attributable deaths by regulating nicotine in combustible cigarettes and banning flavoring in tobacco. Our goal was to render traditional cigarettes minimally or nonaddictive and to sharply accelerate declines in smoking. There were uncertainties about the health effects of e-cigs, but we saw them as a less harmful alternative to cancer-causing tobacco for addicted adult smokers.

I believe e-cigs still offer that promise. But a sharp rise in youth e-cigarette use, reflected in the 2018 National Youth Tobacco Survey, prompted us to act: We sought to limit e-cigs' availability and appeal to kids by putting new restrictions on the sale of flavored liquids and requiring earlier applications from companies for approval.

The use of e-cigs by children threatened the existence of the entire product category even before the recent outbreak of lung injuries showed the potentially deadly consequences of misusing vaping products. That threat has been compounded now that legally sold e-cigarette hardware is being used to vape illegal CBD and THC liquids.

The industry's failure to confront the youth vaping epidemic leaves e-cig companies vulnerable to those who doubt that the major brands are responsible stewards of their products. Critics will conflate legitimate vapes with illegal ones precisely because the companies have not seriously sought FDA approval. Moreover, in many cases, it's legal vaping pens that kids are using with THC and CBD. The major e-cig manufacturers have too easily let their products get into the hands of children.

The FDA plans to require manufacturers to submit applications in the next year. Today, all e-cigarettes in the marketplace are there because the FDA has exercised its enforcement discretion. The agency can remove products that won't be able to meet their legal obligation to show a net public-health benefit.

Removing legally sold products will swell the market for counterfeit goods. Congress can help address that problem by directing more resources, perhaps through e-cigarette user fees, for the FDA's field operations so the agency can more forcefully target counterfeit and illegal products. Congress might also need to extend FDA oversight of vape pens that aren't explicitly marketed for aerosolizing nicotine derived from tobacco, which is the current legal hook for FDA regulation.

Manufacturers need to separate legitimate e-cigs from illegal adulterants by publishing detailed information on their ingredients, by taking meaningful steps to limit youths' access to their products and its appeal to them, and by fully embracing an FDA application process that they've largely fought.

Bright lines must be drawn between less-harmful ingredients and those that cause undue risk. That would arm regulators with the information to crack down on illegal and dangerous vape juices. It's also time to end the political ambivalence that allows THC and CBD to evade oversight.

The longer that legitimate e-cigarette companies reject their obligations to help distinguish acceptable products from dangerous ones, the more they will be lumped in with those contributing to the growing glut of illegal products. That's bad for preserving their businesses, and it's bad for protecting the public health.

Scott Gottlieb, a resident fellow at the American Enterprise Institute, is a former commissioner of the Food and Drug Administration. He consults for and invests in biopharmaceutical companies. He wrote this article for the Washington Post.