Public health officials revealed Friday vitamin E acetate has been found in the lungs of people suffering damage linked to vaping as President Trump said he wants to raise the legal age for vaping to 21.

An anonymous vaping habits survey released by Illinois health officials indicated those with lung damage used black-market THC vaping products. (THC is the psychoactive ingredient in marijuana.)

As of Tuesday, there had been 2,051 confirmed and probable lung injury cases associated with e-cigarettes or vaping products in 49 states, the District of Columbia and the Virgin Islands, the Centers for Disease Control and Prevention reported, with 39 of the cases fatal.

In a telebriefing Friday, CDC officials told reporters investigators regard vitamin E acetate as “a very strong culprit of concern” but there still may be other compounds or ingredients contributing to the lung damage problem.

Anne Schuchat, the CDC’s principal deputy director, said tests have been conducted for a wide variety of substances, including plant oils and petroleum distillates.

“No other potential toxins were detected” in the lungs of victims, she said.

A CDC report said vitamin E acetate was found in all 29 samples of lung fluid examined, with THC present in 23 of the samples and nicotine in 16. Most of those stricken with lung damage vaped THC. Previously, researchers had found vitamin E acetate in product samples tested.

Vitamin E acetate, which is used in food and skin care products without adverse effects, is used as a cutting agent or additive on the cannabis black market because it is colorless, odorless and inexpensive, and has a consistency similar to THC oil. As it is heated beyond its 363-degree boiling point, however, it begins to decompose.

The Illinois survey of 4,600 people who vape found 94% of respondents reported vaping only nicotine while 21% vaped only THC and 11% said they vaped both. A subset of 66 people who suffered lung damage indicated they were nine times more likely to have used illicit products and to have indulged more often.

Trump said the administration is getting to raise the vaping age to 21 “or so” but may not go through with plans to ban flavored products. Several state and local governments already have raised the legal age.

Juul Labs, the nation’s biggest e-cigarrettes seller, Thursday said it would eliminate its mint-flavored pods, which are popular among teenagers, leaving just tobacco and menthol as its only offerings.