What's behind the recent vaping deaths? Health officials may have a lead.

*Editor’s note: This story was updated Sept. 6 with new CDC data on suspected lung illness cases and deaths.

Federal and state health officials this week announced they have identified high levels of vitamin E acetate in samples of marijuana vaping products that have been linked to a deadly lung illness affecting patients across the country.

Background: A deadly mysterious lung illness leads to new concerns about vaping

Providers this summer began alerting CDC to a mysterious, severe lung illness that appears to be tied to e-cigarette use and vaping.

Emily Chapman—CMO at Children's Minnesota, which has treated four teenagers between the ages of 16 to 18 with the lung illness—said teenagers have presented with symptoms such as abdominal discomfort, coughing, fever, and shortness of breath. Chapman said standard treatments, including antibiotics and oxygen support, in some cases did not stop the symptoms. A few teens went on to experience respiratory failure and had to be placed on ventilators. Chapman said providers then treated the patients with steroids, which improved the patients' health.

CDC on Friday told reporters the agency is tracking 450 possible cases reported by 33 states. So far, three patient deaths and one suspected death have been tied to the illness. Public health officials in Oregon this week announced a patient had died after using a legally purchased vaping product containing tetrahydrocannabinol (THC), which is the high-inducing chemical found in marijuana. Oregon public health officials declined to disclose the patient's age or gender, but said the patient was middle-aged and an "otherwise healthy" person who "quickly became very ill" with lung disease. CDC is still investigating the death.

Health officials said it is unclear whether the lung illnesses are associated with e-cigarettes or the contaminants or ingredients inhaled through the devices, but they noted that patients with the condition have described using vaping "home brews," e-cigarettes containing THC, nicotine-based products, and other substances.

FDA and state public health departments are testing samples of nicotine, THC, and other chemicals used in vaping products to try to find a common compound.

Health officials identify chemical common in vaping illness cases

During a telephone briefing with states this week, FDA officials said they have found vitamin E acetate in many of the tested THC samples, several state officials who took part in the call told the Post.

Vitamin E is found naturally in foods such as canola oil, olive oil, and almonds, the Post reports, and it is commonly used in nutritional supplements and topical skin treatments. However, New York's Department of Public Health said the health risks of inhaling the oil-like substance are unknown.

"Vitamin E acetate is a commonly available nutritional supplement that is not known to cause harm when ingested as a vitamin supplement or applied to the skin. However, the Department continues to investigate its health effects when inhaled because its oil-like properties could be associated with the observed symptoms," the state said in a press release.

Individuals on this week's call told the Post FDA found vitamin E acetate in 10 of the 18 THC products it tested. FDA did not find any traces of vitamin E in the 12 tested nicotine samples, the state officials said.

FDA spokesperson Michael Felberbaum on Thursday said, "The number of samples received continues to increase, and we now have over 100 samples for testing."

A New York health department spokesperson on Thursday said FDA's findings appear to confirm the state's analyses. The spokesperson said New York investigators last week found "very high levels of vitamin E acetate in nearly all" of its tested THC samples, but none were present in tested nicotine samples. The spokesperson said the state had tested more than a dozen samples.

New York State Health Commissioner Howard Zucker said in a statement Thursday, "Vitamin E acetate is not an approved additive for New York State Medical Marijuana Program-authorized vape samples and was not seen in the nicotine-based products that were tested. As a result, vitamin E acetate is now a key focus" of the state's investigation.

While THC showed up in many of the samples, FDA's Felberbaum clarified that "[n]o one substance, including vitamin E acetate, has been identified in all of the samples tested." He added, "Importantly, identifying any compounds that are present in the samples will be one piece of the puzzle but will not necessarily answer questions about causality" (Boyles, MedPage Today, 9/6; Sun, Washington Post, 9/5; Richtel, New York Times, 9/65; Richtel, New York Times, 9/46; Zarkhin, The Oregonian, 9/3; Flaccus, Associated Press, 9/4; Flaccus, AP/KTVZ, 9/4).