An opioid combo called “gray death” is the latest dangerous trend in drug use, and one that highlights the growing threat of the burgeoning drug epidemic, authorities warn.

The drug looks like concrete mix and can contain what could essentially be a suicide cocktail—everything from heroin to fentanyl to carfentanil to a synthetic opioid called U-47700, according to the Associated Press. The powerful cocktail typically includes several drugs, but the exact combination and strength often isn’t known to users.  

"It's mad science and the guinea pigs are the American public," the DEA’s Russ Baer told NBC News. "The ingredients come from abroad but this is made in America."

So far, the new drug mix has mostly popped up in Gulf Coast states, though it’s also shown up in Georgia and Ohio. “We’ve not yet seen a national proliferation of the ‘gray death’ substance,” Baer said. 

Some of the drugs in gray death can be absorbed through the skin, Deneen Kilcrease of the Georgia Bureau of Investigation told the AP. "Gray death is one of the scariest combinations that I have ever seen in nearly 20 years of forensic chemistry drug analysis," she said.

One of the ingredients, U-47700, was placed last year in the DEA’s most dangerous drugs category, and was linked to dozens of deaths in New York and North Carolina. It was even found in some of the pills at Prince’s mansion after his April 2016 fatal overdose.

In the last three months, Georgia clocked at least 50 gray death-related overdoses, mostly in the Atlanta metro area. In Ohio, authorities near Cincinnati have watched the compound stream in for a few months. 

“We have put out the bulletin to all of the other drug task forces in Ohio,” Lorain County detective Jim Larkin told CBS. 

And, as is often the case, the sinister name doesn’t seem to be deterring users. "It's amazing to me that they find out one of their friends died from an overdose from the drug and they immediately try to find out where he got it from because they want to try it too," Larkin said. 

"Why anybody—'Hey here's some gray death'—but what do you think is going to happen to you? Why do you think it's called gray death?"