Deadly 'Zombie Drug' Believed to Contain Human Bones Wreaks Havoc in West Africa
sciencealert.com
sciencealert.com
I mean... the users will be lucky if some of the volume is a substance as harmless as bone, the rest of that list will kill you and shouldn't be casually mixed.
Formaldehyde in particular should simply be avoided, although I guess dying of cancer is a distant prospect for a fentanyl addict, and an unlikely one. More of a goal really.