Drug cartels in Mexico are testing their latest risky formulas for fentanyl production on rabbits, chickens and humans amid a global crackdown on synthetic opioids that has forced the criminal groups to develop other ways to produce drugs.

According to the New York Times, cartel members visited homeless people’s encampments. They paid up to $30 per person for anyone volunteering to inject the new concoction into themselves as the criminal groups observed the drug’s effects on them.

One of the two men living in the camp who spoke to the Times, Pedro López Camacho, said he volunteered for the risky test several times, and the cartels were even visiting every day at some point. 

He said they would snap and film his reaction to the effect of the new formulas.

According to him, many people died in the camp from the drug’s effects. 

“When it’s really strong, it knocks you out or kills you,” said Mr Camacho of the drugs he and others were given. “The people here died.”

The Mexican drug cartels are being forced to devise extremely risky new methods to maintain potent fentanyl production after China, the original source of chemicals for production, restricted exports of the necessary raw ingredients.

Members of the cartels told the Times that the new experimentation involves combining the drug with a wider range of additives — including animal sedatives and other dangerous anaesthetics.

The mixtures were tested on human subjects, rabbits, and chickens for potency. 

If the rabbits survive beyond 90 seconds, the drug is deemed too weak to be sold to Americans, according to six operatives and two U.S. Embassy officials who monitor cartel activity.