 | Grey death ingredients and their concentrations are unknown to users, making it particularly lethal. Because these drugs can be absorbed through the skin, simply touching it puts users at risk.
Last year, the U.S. Drug Enforcement Administration listed U-47700 in the category of the most dangerous drugs it regulates, saying it was associated with dozens of fatalities. Some of the pills taken from Prince's estate after the musician's overdose death last year contained U-47700. | 
 A typical new combination also being seen is heroin combined with 3-methylfentanyl, a more powerful version of fentanyl |