The number of vaping-related lung illnesses has risen to 530 probable cases, according to an update on Thursday by the Centers for Disease Control and Prevention, and a Missouri man became the eighth to die from the mysterious ailments.
During a news briefing, Dr. Anne Schuchat, principal deputy director of the C.D.C., said officials expect more deaths because some people are suffering from severe lung illnesses.
But the nation’s public health officials said they still were unable to pinpoint the cause, or causes, of the sicknesses that have resulted in hundreds of hospitalizations, with many in intensive care units.
Dr. Schuchat said some patients are on ventilators and therefore are unable to tell investigators what substances they vaped.
“I wish we had more answers,” she said.
The C.D.C. provided the first demographic snapshot of the afflicted: Nearly three-quarters are male, two-thirds between 18 and 34. Sixteen percent are 18 or younger. “More than half of cases are under 25 years of age,” Dr. Schuchat said.
Illnesses have now been reported in 38 states, and one United States territory.
In the most recent case, in St. Louis, officials said on Thursday that a man in his mid-40s who had chronic pain had begun vaping last May. He was hospitalized Aug. 22 with respiratory problems and died on Wednesday.
“He started out with shortness of breath and it rapidly progressed and deteriorated, developing into what is called acute respiratory distress syndrome (ARDS),” said Dr. Michael Plisco, a critical care pulmonologist at Mercy Hospital St. Louis. “Once the lungs are injured by vaping, we don’t know how quickly it worsens and if it depends on other risk factors.”
He and other officials said they did not know what substance the patient had been vaping, but Dr. Plisco said in an interview that tissue samples from his lungs showed cells stained with oil.
Some products include oils that if inhaled — even small droplets — can cling to the lungs and airways and cause acute inflammation, doctors have said.
The first case in Canada also emerged this week. Officials there released information about a teenager in Ontario who was put on life support in an intensive care unit, but has now recovered.
The spate of illnesses this summer, coupled with the rising popularity of teenage vaping, has led a few states and the Trump administration to propose outlawing flavored e-cigarettes. Public officials hope restricting flavors that hold particular appeal for youth may discourage teenage use and adoption of vaping. Early results of an annual survey released on Wednesday show that teenage vaping has doubled since 2017.
Vaping typically entails inhalation of aerosolized substances, usually nicotine or THC — the psychoactive ingredient in marijuana — mixed with solvents or other chemicals.
The C.D.C. reiterated that many of the people who have gotten sick have used THC-based products, some obtained on the street, rather than from retailers in states where recreational or medical marijuana is legal. But C.D.C. officials continued to emphasize they have not identified a single clear chemical or cause of the outbreak. The officials said patients have reported using THC, THC and nicotine and for some, just nicotine.
The C.D.C. has said that to be safe for the time being, people should not vape anything at all. The lack of answers has begun to elicit frustration from various camps, including consumers, policy experts and industry groups. Since mid-August, when public health officials first disclosed that nearly three dozen people had gotten sick, a clear cause has not been identified. The agencies have pointed to the complexity of testing products and challenges of getting detailed history from patients about their behavior.
At the same time, a growing number of critics have said, there should be clearer results from the massive machinery of the federal investigation — more than 80 people at the C.D.C. working on the issue and a Food and Drug Administration lab in Cincinnati working with more than 150 samples from patients who got sick.
“We are not getting specific information we need to protect the public,” said Dr. Michael Siegel, a pediatrician at Boston University who has been a strong advocate for the use of e-cigarettes as a less dangerous alternative to traditional smoking. He said that the government has heavily implied that the problem is largely resulting from the use of illicit THC-related vaping products made but has not exonerated e-cigarettes, creating confusion.
“They’re not releasing the number of cases involved with THC,” he said. “That’s information they should be releasing.”
Eric Lindblom, an expert in tobacco policy at Georgetown Law School and a former F.D.A. senior adviser, said that the F.D.A. has the authority to ban the sale of THC vaping liquid, or THC vape pens, even in states where recreational marijuana is legal — or to ban sales that include any solvents other than ones known to be safe.
“They need to do something,” he said. “They should just take action to stop these things. It’s a no-lose situation.”
Mitchell Zeller, director of the F.D.A.’s Center for Tobacco Products, said it would be premature to take further action until “we get answers to these questions.”
“We are in desperate need of facts and evidence,” he said during a news briefing with the C.D.C. on Thursday. He said that there were multiple compounds showing up in the vaping mixtures, including Vitamin E acetate and other additives. He said that Vitamin E did not appear to be the sole factor but did not elaborate on other substances involved.
Mr. Zeller also said that the F.D.A.’s office of criminal investigations has begun “parallel investigative efforts.” He declined to specify any target of those efforts or whether an enforcement action is forthcoming, but he did say that particular arm of the FDA has gotten involved because it “has special investigative skills.
Dr. Schuchat from the C.D.C. said she understood the desire for more precise information. “We absolutely want to do that,” she said but added that in providing partial information, officials might “prematurely reassure” consumers about the safety of a product that ultimately turns out to be problematic.
One outstanding question, for instance, is whether there might be any connection between the recent bust in Wisconsin of an alleged vaping ring and the outbreak of illnesses. The bust involved seizing 57 Mason jars filled with liquid thought to be THC, or contain it, and thousands of empty vaping cartridges.
The bust and the outbreak come against a backdrop of tremendous uncertainty, even confusion, at the federal level over the governance of both e-cigarettes and, more so, marijuana.
With e-cigarettes, the F.D.A. has for years been developing regulations and policy about what products to allow into the market and under what circumstances. Recently, a federal court ruled that the F.D.A. must demand that e-cigarette makers provide evidence by May of next year about their public health benefits or be pulled from the market.
The issue is even trickier with marijuana, which the federal government still considers to be a Schedule 1 drug, a category it shares with such deadly substances as heroin. Yet with nearly a dozen states having legalized marijuana, and nearly three dozen allowing medicinal use, the federal government has essentially stood on the sidelines, trying to balance the growing political momentum behind legalization — as well as a burgeoning industry of cannabis and hemp products — against the uncertain health effects and longstanding federal policy.
Mitch Smith contributed reporting to this article.