The severe respiratory sicknesses have largely been linked to vaping products from the illicit market, but the CDC said at least a few illnesses nationwide were “anecdotally” linked to licensed cannabis dispensaries. Some patients also reported using nicotine vapes. Many Massachusetts marijuana companies have insisted their products don’t contain vitamin E acetate, which has been used to thicken or thin concentrated THC, the main psychoactive chemical in pot.

Calling the information a breakthrough in their months-long investigation, authorities at the US Centers for Disease Control and Prevention said vitamin E acetate, an oily substance added to some vape cartridges, is a “very strong culprit” behind the lung illnesses, though they said other ingredients may also be contributors.

Federal officials on Friday identified one possible cause of the vaping-related illnesses that have killed at least 40 people nationwide and sickened more than 2,000.


Cannabis advocates in the state hoped the news would help move officials toward allowing vaping products back on store shelves after Governor Charlie Baker banned sales of all nicotine and marijuana vapes in late September.

“The legal, regulated products in Massachusetts are safe,” said Will Luzier, a medical marijuana patient who sued to lift the ban. “Once all the harmful additives are investigated and regulated, the sale of vaping products should go on.”

But local doctors stressed the investigation is far from over.

“Even if they take vitamin E out, the THC is cut with oils, so they’ll likely use something else that could potentially be harmful to the lungs,” said Dr. Alicia Casey, a pediatric pulmonologist at Boston Children’s Hospital who has treated several young patients with lung damage from vaping.

The vitamin E acetate was confirmed to be a contaminant through analysis of fluid samples taken from the lungs of 29 patients across 10 states, a CDC report released Friday said.


Researchers found vitamin E acetate in all 29 fluid specimens, and the majority of those patients reported using products containing THC.

“Until the relationship of vitamin E acetate and lung health is better characterized, it is important that vitamin E acetate not be added to e-cigarette, or vaping, products,” the CDC wrote in the report.

In a phone briefing Friday, Dr. Anne Schuchat, principal deputy director for the CDC, said researchers continue to be most concerned about products coming from the illicit market, but they aren’t ready to rule out state-licensed dispensary products, either.

“It is possible that vitamin E acetate may be included in some dispensary controlled products in one state or another,” Schuchat said. “And it’s possible it’s there intentionally, and it’s possible it’s there unintentionally.”

Illinois’s state epidemiologist, Jennifer Layden, said at the briefing her state hasn’t seen any cases connected with its medical marijuana program. Illinois legalized recreational marijuana this year, but those sales won’t take effect until January.

Schuchat emphasized that “the information is continuing to be collected.”

“There’s some anecdotal information right now about individuals who only report getting products from licensed dispensaries, and exactly what those products are and whether they were as labeled or as expected to be produced is unclear,” she said. “We have a few cases that I’m aware of, but I don’t have the details.”

In Massachusetts, state health officials have reported at least 68 illnesses to the CDC, according to the latest data released by the state Department of Public Health on Wednesday. Three people have died.


Baker banned the sale of all vaping products in Massachusetts for four months in September, saying he wanted to give medical experts time to determine what made people sick. His decision was applauded by many doctors, but criticized by some regulators, cannabis consumers, patients, and others who said his ban would send people to dangerous illicit-market vapes.

Baker spokesman Terry MacCormack said Friday “the administration is encouraged that the Centers for Disease Control is making progress in identifying possible elements that could be causing these illnesses.”

Dr. Ryan Zaklin, a Salem physician who specializes in cannabis medicine, said he doesn’t believe vapes would be safe, even without vitamin E or other known harmful additives in them. He said he wouldn’t recommend them to his patients unless they were rigorously tested and regulated the way the federal government treats medicines.

“Cannabis has been smoked for thousands of years,” Zaklin said. “These vape cartridges are brand new. You’re inhaling vegetable oil. You’re a guinea pig. It’s an experiment.”

But pot industry leaders said they hoped the news meant regulators would soon have enough confidence in the products’ safety to resume sales.

“It’s a positive step in the right direction,” said David Torrisi, executive director of the Commonwealth Dispensary Association. “Obviously we would like to sell vapes and we feel that our medical patients would like us to be selling vapes, but it’s important that the health and medical professionals do their work.”


Baker has defended his ban amid legal challenges, arguing that without more information about what’s causing the illnesses, he’s not prepared to allow any licensed vaping products to be sold.

“For me, the whole thing is terribly troubling,” Baker told reporters this week, “because we haven’t been able to secure an answer from any of these state and federal agencies that are looking into this yet that makes it possible for us to say to the public, ‘This is the answer. Don’t do this.’ ”

A judge this week ruled that the Cannabis Control Commission, not Baker, had the authority to determine next steps on the ban for medical marijuana products exclusively. The ban on vapes for patients could lift at noon Tuesday if the commission doesn’t act to uphold it before then.

Shaleen Title, one of the state’s five cannabis commissioners, tweeted Friday that the commission needs information about whether any illnesses in Massachusetts are connected to regulated vaporizers, and it has requested that data from state health officials.

“One obvious thing we need is information as to whether any of the illnesses are linked to regulated products, and which ones, so we can consider appropriate action,” she wrote.

The outbreak of lung illnesses has also drawn attention to widespread vaping among teenagers. On Friday, President Trump told reporters he wanted to limit flavors in vaping products and raise the legal age to buy them to 21 across the country.


Felicia Gans can be reached at felicia.gans@globe.com. Follow her on Twitter @FeliciaGans.