(WAND) - 13 people have died from a mysterious lung illness linked to vape pens, and 805 have been hospitalized in nearly every state in the country.
The soaring popularity of vape products has led to many knock-offs being sold, some which contain dangerous chemicals.
"We are dealing with a new epidemic," said Dr. Melodi Pirzada, a pediatric pulmonologist at NYU Winthrop Hospital in Long Island, N.Y.
The Centers for Disease Control and Prevention said most of the patients reported using vapes containing THC, the psychoactive ingredient in marijuana.
Some state health officials have indicated that Vitamin E acetate, a solvent used to "cut" cannabis for use in vape pens, may be responsible for the outbreak.
No single substance or product has yet been linked to all of the cases of vaping-related lung disease.
The FDA is struggling to regulate what has rapidly grown into a billion dollar industry with a booming black market.
NBC News commissioned one of the nation's leading cannabis testing facilities to test a sampling of THC cartridges. They tested 18, all obtained from legal dispensaries and unlicensed dealers.
Of the three purchased from legal dispensaries in California, the CannaSafe testing company found no heavy metals, pesticides or residual solvents like Vitamin E.
But 13 out of the other 15 samples from black market THC cartridges were found to contain Vitamin E.
CannaSafe also tested ten of the unregulated cartridges for pesticides. All ten tested positive.
The products all contained myclobutanil, a fungicide that can transform into hydrogen cyanide when burned.
"You certainly don’t want to be smoking cyanide," said Antonio Frazier, the vice president of operations at CannaSafe. "I don’t think anyone would buy a cart that was labeled hydrogen cyanide on it."
In one case, an 18-year-old boy arrived at the hospital with pneumonia-like symptoms. But within 48 hours, his condition deteriorated rapidly and he was placed on a ventilator.
He spent five days on life support before he was able to breathe on his own and recover with the help of steroids.
Over the summer, an 18-year-old girl arrived at UCLA Health with a bad cough, fevers, nausea and labored breathing. Within 48 hours, her lung function deteriorated to the point that doctors sent her to the ICU and hooked her up to a respirator.
The teenager, who reported having vaped tobacco and pot products every day for the past two years, ultimately improved and was released from the hospital, NBC News reports.
Downtown Los Angeles features a 12-block area filled with shops selling vape supplies that can be used in bootleg products.NBC News
Officials said anyone who buys bootleg vapes is putting themselves at risk.
The American Vaping Association insists the outbreak is linked to THC oils and knock-offs.
Laboratory tests found no pesticides or residual solvents in these marijuana cartridges.NBC News
One of the shops visited by NBC News in Los Angeles sold packaging for Dank Vapes Gorilla Glue, the same brand of vape that Castillo was using before he landed in the hospital ICU.