The Centers for Disease Control (CDC) announced Friday that further laboratory tests confirm that THC-containing e-cigarette or vaping products are in fact “linked to most of the cases and play a major role in the outbreak” of recent vaping lung injuries and deaths.

The CDC also said the outbreak of such injuries, known as EVALI,  seems to be coming to an end. Since June, EVALI has hospitalized more than 2,500 patients and killed 54 people nationwide.

Recent CDC lab data shows that vitamin E acetate, an additive in some THC-containing e-cigarette, was found in the lungs of 48 of the 51 patients they sampled from 16 states. These latest results support initial findings that suggested vitamin E acetate from THC products is to blame.

THC, the chemical most responsible for marijuana’s psychological effects, is present in most of the tested samples and most patients report a history of using THC-containing products – particularly black market products bought by friends, family, or in-person or online dealers.

The EVALI outbreak coincides with a fast-growing THC-vaping black market supplied by domestic and international criminal organizations. Ray Donovan, the Drug Enforcement Agency’s Special Agent in Charge in New York, said the number of illegal THC vaping products seized by their office has grown exponentially in the state from just 38 in 2017 to more than 210,000 in 2019.

“They’re being manufactured on the West Coast, Asia or in Mexico and smuggled by international organizations into the United States,” Donovan said. “It’s very easy. You can go online and get this product. You can have it delivered to your doorstep”

Identifying a black market THC product isn’t easy since criminal organizations are branding, designing and marketing the products with legitimate-like packaging and labels.

“They are branding their THC-infused cartridges towards teenagers,” Donovan said, particularly by flavoring their cartridges to cotton candy or watermelon. Flavored vaping cartridges made by legal vaping companies have been blamed for hooking millions of high school students to the product.

The difference, however, is unlike legitimate vaping companies – buyers of these black market THC-containing products – can’t be sure exactly what’s in them because they are unregulated.

“There’s no quality control here. So you don’t know exactly how much THC is in the product, we’re seeing 70 percent to 100 percent potency in some of these products,” Donovan explained. “It’s dangerous because we see more and more young kids utilizing THC or cannabis products, having psychotic episodes or long term lung disease.”

Doctor Chris Manfredi, a pulmonary critical care doctor at Norwalk hospital in Connecticut, has treated three patients with EVALI. Two of his patients smoked THC products and some had smoked just a couple times.

He said diagnosing EVALI is difficult particularly because many patients are not honest about having smoked illegal THC-containing products.”No one wants to admit it,” Dr. Manfredi said. “The majority of the patients are young people under age 35.”

Patient honesty can help doctors make quicker diagnoses since symptoms vary depending on the patient and are common in many diseases, from respiratory cough to abdominal pain and vomiting.