An eight death from vaping has been reported in the United States. It was of a man in his mid-forties in Missouri.

Missouri health officials announced that the man normal lung function before he started to vape in May. He developed mild respiratory symptoms that worsened, and was hospitalised on August 22.

“This is an unfortunate case of a young man with no prior lung illness who started vaping because of chronic pain issues,” Dr. Michael Plisco, Mercy Hospital St. Louis critical care pulmonologist and medical director of Mercy’s extracorporeal membrane oxygenation (ECMO) program said in a media release, reported by Fox8

“He started out with shortness of breath and it rapidly progressed and deteriorated, developing into what is called acute respiratory distress syndrome (ARDS). Once the lungs are injured by vaping, we don’t know how quickly it worsens and if it depends on other risk factors.”

Vaping-related illnesses were previously linked to seven previous deaths — two in California and one each in Kansas, Illinois, Indiana, Minnesota, Oregon. CDC health officials said on Thursday they expect more deaths to be reported.

There have been 530 confirmed and probable cases of lung injuries related to e-cigarettes as of September 17, the US Centres for Disease Control and Prevention said Thursday. That’s 150 more than was reported on September 11.

As of September 17, there have been vaping-related illnesses in 38 states and one US territory, the CDC said. Among the cases for which patients’ sex and age are available, 72% are in men, 67% are in people ages 18 to 34, 16% are in people younger than 18 and 17% are in people age 35 and older. More than half of the cases are in people younger than 25.

Still, health officials said they haven’t found a definitive cause or a clear connection between cases, and they warned that patients worried about becoming ill from vaping should refrain from using e-cigarettes.

Hundreds of cases, multiple substances

On Thursday, officials from CDC, FDA and states complex investigations, involving hundreds of patients — including some who are reluctant or too ill to talk with investigators — and multiple substances.

“I wish we had more answers,” Dr. Anne Schuchat, principal deputy director of the CDC, said during a media briefing on Thursday.

The CDC and various state health departments have reported widespread use of products containing THC, or tetrahydrocannabinol, the psychoactive substance within cannabis, among people who became ill. But health officials emphasized Thursday that not all people who became ill had used THC, and many had used multiple substances.

Mitch Zeller, director of the US Food and Drug Administration’s Center for Tobacco Products, said the agency has collected more than 150 vaping product samples for analysis in its forensic chemistry centre and the number continues to grow. Investigators had previously mentioned finding vitamin E acetate in some samples, but lab tests show a “mix of results,” Zeller said, and no one ingredient, including vitamin E, has shown up in all of the samples.

Zeller also said the FDA has activated its law enforcement arm, the Office of Criminal Investigations for a parallel investigation to identify what is making people sick and how it’s supplied. Zeller said the investigation is ongoing, but the office is not pursuing any prosecutions related to personal use of e-cigarette products.