Black-market marijuana vape cartridges have been found to contain hydrogen cyanide in laboratory testing commissioned by NBC News. The network reports it asked a California cannabis testing facility to examine a sample of 18 cartridges containing THC, the psychoactive ingredient in marijuana. The three purchased from legal dispensaries found no toxins, such as heavy metals or pesticides, but the other 15 samples from black-market THC cartridges gave troubling results. They all contained myclobutanil, a fungicide that can transform into hydrogen cyanide when burned. Thirteen out of the 15 contained Vitamin E acetate, which some health officials have blamed for the deaths and lung illnesses linked to vape pens. Ten of the unregulated cartridges also tested positive for pesticides. “You certainly don’t want to be smoking cyanide,” Antonio Frazier, the vice president of operations at testing lab CannaSafe, told NBC News. “I don’t think anyone would buy a cart that was labeled hydrogen cyanide on it.” The Centers for Disease Control and Prevention reported Thursday that 12 people have now died from mysterious illnesses believed to be related to vaping, with the number of confirmed cases at 275.