Marijuana regulators said in documents released Thursday night that testing had found the presence of lead in over a dozen quarantined vape products.

The Cannabis Control Commission has been testing vaping products that have sat on shelves since September due to Gov. Charlie Baker’s vape ban. Initial concerns focused on products containing vitamin E acetate, an additive identified by the Centers for Disease Control and Prevention as contributing to the national outbreak of illnesses.

An initial 91 tests from November and another 109 tests from December, released Thursday, did not find the presence of vitamin E acetate in any of the regulated vapes. But the commission said that out of 109 vapes recently tested in December, 13 showed presence for lead.

“These findings make clear that the Commission should, and will, continue its investigation into vaping products,” the commission said. “As additional information and findings become available, the Commission will continue to share them with the public.”

Citing the ongoing testing, the commission said it would not identify which of the 22 tested dispensaries the products were from.

The problem isn’t with the way the cannabis concentrate was manufactured. The commission said that all of the vaping concentrate they recently tested had initially passed lab tests for heavy metals. The cannabis concentrate likely had been contaminated by the vaping device.

“The product that was acquired and purchased prior to the ban had been previously tested for contaminants and passed that screen,” Shawn Collins, Cannabis Control Commission’s executive director, said at a hearing on Thursday, in an update to the commission about the metals testing. “The contaminants may have developed over time.”

Vapes that had lead in concentrations greater than 500 parts per billion, and subsequently failed the test, included Sativa Strawberry Cough, Concentrate-300mg Vape Pens Spiked Sativa Lemon Ice, Cannabis TerpCart GDP, UKU CO2 Double Dr m (H), UKU CO2 Gelato (H), UKU CO2 Wedding Cake (H), CuraSlim CO2 Strawberry, DART-Jack Herer-500MG, DART -Northern Lights -500MG, Cannabis Terp Cartridge, Granddaddy Purple, Vape Rythm Balance Cartridge Kimbo Kush Concentrate, Vape Rythm Energize Pen Grady’s Cure Concentrate and T-Pen Bulk- AC/DC.

Collins said that if consumers had vaping products that they purchased prior to the ban, they may contain lead.

“If that product has been sitting, and purchased and acquired before the initial vape ban, that product as it sits may have contaminants,” Collins said. “That’s why the second screen we’ve conducted includes a screen for heavy metals… and the disclosure of what the hardware is comprised of.”

The findings highlight the concerns that e-liquid is being contaminated by the devices that contain it. In February 2018, Johns Hopkins Bloomberg School of Public Health discovered that vaping liquid was contaminated with metals when it came into contact with the heating coils.