According to DEA documents, levamisole is still in over 80 percent of the cocaine moving around the US, as of last summer. The mystery of the tainted cocaine persists.

The going probable theory about why levamisole is being cut into cocaine at the source (South America) instead of North America (one typically wants to ship a drug as pure as possible for less bulk and then cut it when it gets across the border): It passes street tests for purity. The bleach tests and all that. Which means that South American producers are trying to trick Central American (mostly Mexican) narcos into moving stuff that isn't 100% pure to increase the producers' margins.

But that theory has some weaknesses: How did 80% of the South American drug producers figure out that this was a good idea? How have the Mexican narcos not figured it out yet? Or if the Mexican narcos have figured it out, why would they accept/be using this relatively expensive cut that not only increases their bulk—therefore increasing their smuggling risk—but has become a p.r. liability?

Sometimes I wish Walter White in Breaking Bad—the dorky chemist who falls into the meth netherworld—was a real guy.

He could explain all of this to me.