A pioneering test found a toxic stew of dangerous chemicals — including formaldehyde and hydrogen cyanide — in the vapor produced by some illicit THC vaping cartridges, according to data shared with NBC News.

Federal health officials and private companies have previously published test results on the cannabis oils used in vaping devices, but the new report from the CannaSafe lab in California is believed to be the release of the first findings analyzing the vapor people suck into their lungs.

In all six bootleg THC cartridges it tested, CannaSafe found the vapors they produced were filled with high levels of pesticides and other harmful substances. One of the illicit products, Maui Waui, contained 1,500 times the legal limit of pesticides.

"It had everything bad in it," said Antonio Frazier, the vice president of operations at the Los Angeles-based CannaSafe, one of the nation's leading marijuana testing firms. "If you look at some of the [Centers for Disease Control and Prevention] data for fatal dosing, I'd be willing to bet that some of these are over what they would consider a fatal dose."

The CannaSafe lab in California analyzed vapor from illicit THC oils and found high levels of dangerous chemicals. NBC News

Tests done on the vapor generated by seven THC cartridges purchased at licensed dispensaries turned up no indication of dangerous chemicals — when heated at the industry-recommended standard temperature of 3 volts.

But many vaping pens allow users to crank up the heat to twice that, and the CannaSafe tests showed that doing so has harmful consequences.

"When you vaporize stuff at too high a temperature, it's much more dangerous than a cigarette," CannaSafe President Aaron Riley said.

He added: "People don't die from smoking a pack of cigarettes, which is what we're seeing with some of these illicit vape products. People are actually dying over a month of use."

Health experts said the results underscore the dangers of vaping amid a sweeping outbreak of mysterious lung injuries linked to the use of THC oils. The vapor analysis findings also raise questions about why the federal government hasn't conducted its own vapor tests.

A CDC spokeswoman confirmed to NBC News that it has not yet tested the aerosol emissions from vaping devices but plans to do so in “the next couple of weeks.” Karen Hunter said CDC researchers have focused on analyzing the lung fluid from patients stricken with vaping-related illnesses.

In the past seven months, vaping-related ailments have claimed the lives of 39 people and sickened more than 2,000 others. The condition has affected mostly young people, triggering a rapid onset of breathing problems and other life-threatening symptoms.

Earlier this week, federal health officials announced they had identified a "very strong culprit" in the rash of injuries — a form of Vitamin E.

Investigators found vitamin E acetate, an oily supplement commonly used in skin care lotions and other cosmetic products, in all 29 of the fluid samples taken from the lungs of patients suffering from vape-related illnesses. The substance is sometimes used as a cutting agent in bootleg THC oils, allowing dealers to dilute the product and therefore increase profits, federal health officials say.

But even the CDC acknowledges that the health crisis may not be tied exclusively to Vitamin E.

Dr. Melodi Pirzada, a pediatric pulmonologist at NYU Winthrop Hospital in Long Island, New York, said it's critically important to analyze the vapors generated from heating THC oils.

"It's a great idea to test the vapors," Pirzada said. "That tells you exactly what people are inhaling."

The results of CannaSafe's vapor analysis were released less than two months after NBC News commissioned the lab to analyze THC oils in a variety of black-market products. In all 10 illicit cartridges tested, pesticides were found, including myclobutanil, which transforms into hydrogen cyanide when burned.

In order to analyze the vapor, CannaSafe researchers assembled new testing devices and a new protocol, a process that took roughly a month.

CannaSafe tested the vapor from two counterfeit THC oil cartridges, knock-offs of the brands Kingpen and STIIIZY, revealing the presence of significant levels of carbon monoxide and formaldehyde. The vapor from the counterfeit Kingpen cartridge was also found to contain hydrogen cyanide.

The company also tested an illicit product called Dank Vapes, which the CDC says was used by many of those suffering from vape-related illness. The Dank Vapes vapor was found to contain seven pesticides, as well as significant levels of vitamin E and trace amounts of formaldehyde.

The CannaSafe tests also detected the presence of lead in the oil of several illicit products, company executives said, suggesting the cheap metals used to produce the cartridges and heating coils, mostly imported from China, may also pose health dangers.

"We found actually five times the amount of the legal concentration of lead in the Maui Waui [oil]," Frasier said. "Most likely that's the hardware leaching back into it over time. I'm sure that's why these numbers are so gross because the hardware isn't controlled."

Of all the substances detected in the vapor tests, Pirzada she was particularly concerned about the presence of formaldehyde, a chemical also known to exist in electronic cigarettes.

"Formaldehyde is a very toxic material, but does it explain the real problem in these patients we're seeing? I do not know that," she said.

The long-term effects of vaping, if any, are still unknown, medical experts say.

Dr. Mickey Sachdeva, a pulmonologist at Kaiser Permanente in Fresno, California, said the vapor test results amount to "further proof that vaping is harmful and can lead to serious health issues."

But Sachdeva emphasized that the root cause of the outbreak remains an unknown. "There are ongoing studies trying to figure out which substances are to blame, but I would advise anyone who is vaping to stop immediately," he said.