Officials have identified Vitamin E Acetate as a "strong culprit" in the vaping-related lung injuries that left thousands sick and 39 people dead, the Centers for Disease Control and Prevention said on Friday.
Dr. Anne Schuchat, principal deputy director of the CDC, described the Vitamin E Acetate link as a "breakthrough" in the investigation, but cautioned that the news does not mean the investigation is over.
"These findings do not rule out other possible compounds that may be causing lung injuries but help us better understand potential ingredients that may contribute to the cause of EVALI," Schuchat said during the Friday news briefing. She also stressed that inhaling Vitamin E acetate is very different than applying it as a cream or taking it as a supplement, neither of which is thought to be harmful.
"We are not talking about the Vitamin E capsules that people swallow," Schuchat said. "This is a case of inhaled aerosol."
There have been 2,051 lung illnesses and 39 deaths linked to vaping, according to the CDC's latest numbers.
Seattle public schools filed a lawsuit against Juul Labs and its parent company, Altria Group, on Thursday on the grounds that the e-cigarette company purposely targeted minors with its advertising campaigns.
Juul did not respond to ABC News' request for comment on the lawsuit.
Two surveys published this week in the Journal of the American Medical Association found that mint was the most popular flavor among older high schoolers, and the second most popular flavor among younger high schoolers, who used Juul e-cigarettes.
Nearly 60% of high school students and 54% of middle school students reported that Juul was their preferred e-cigarette brand.
Juul halted sales of the mint e-cigarettes, its best-selling flavor, on Thursday.
The Trump administration said on Friday that it would announce the details for a possible ban on flavored e-cigarettes next week.