The opioid – which looks like a concrete mix – is a highly potent combination of heroin, fentanyl (a synthetic opioid), cafentanil (which is also used as an elephant tranquilizer) and U-47700 (synthetic opioid). 
Since this drug is created in illegal underground labs, users can’t possibly know exactly what they are ingesting or how potent it is. In addition, drugs like “gray death” are so strong, they can be absorbed through the skin and can affect someone who simply touches the powder, Deneen Kilcrease, manager of the chemistry section at the Georgia Bureau of Investigation told the Associated Press.
“Gray death is one of the scariest combinations that I have ever seen in nearly 20 years of forensic chemistry drug analysis,” Kilcrease said. Read more.