Over the course of several months, Fabian Castillo’s ability to breathe grew more difficult until he finally checked into a hospital where X-rays showed severe damage to his lungs. NBC News is now reporting that Castillo’s marijuana cartridge and potential others contained myclobutanil, which when burned, transforms into hydrogen cyanide.

According to Castillo, the vape was working as he expected with no notable oddities, but it turns out, it seems to have been a bootleg product. Castillo spent nine days in a medically induced coma.

The Centers for Disease Control and Prevention claim that the majority of the 805 hospitalizations and twelve deaths are from cartridges containing THC. Certain officials believe Vitamin E acetate, a solvent used for cutting cannabis to be the cause for the outbreak; however, no definitive substance/product has been determined as the cause.

There is one section from the NBC News report that is particularly concerning. According to Cannasafe, a testing company, as high as thirteen out of fifteen black market THC cartridges were found to include Vitamin E. The company also tested 10 of the unregulated cartridges for pesticides and all 10 returned positive. On the bright side, of three carts purchased from legal dispensaries, none contained heavy metals, pesticides or residual solvents such as Vitamin E.

It’s been eight weeks since Castillo’s incident and he still finds difficulty breathing.