A years-long study by the Brazilian police into the "DNA" of cuts in the country's cocaine found that 11 percent of the bulk product (the "DNA" tests were only triggered after a seizure of more than five kilos) is cut with levamisole.
But thirty-five percent of their bulk cocaine is cut with Phenacetin, a non-opioid painkiller that has been banned in the UK since the 1960s, after it was linked to kidney and bladder cancers. Phenacetin has also been linked to the dissolution of blood cells and necrosis of the kidneys.
In short, it's nasty stuff.
And what's in Brazil's cocaine is probably in North America's cocaine as well—levamisole and other cuts have been found in cocaine-producing countries. But why are the producers bulking up their cocaine before smuggling it, thereby increasing their risk of getting caught? (The game used to be to ship purerelatively pure product and bulk it up with cuts once it was over the border.) There are plenty of theories, but that question still hasn't been fully answered.