According to an Associated Press article from 2016, “Chemical weapon for sale: China’s unregulated narcotic”, fentanyl, carfentanil and other highly potent derivatives of fentanyl are actively marketed by several Chinese chemical companies. Carfentanil was not a controlled substance in China until 1 March 2017, and until then was manufactured legally and sold openly over the Internet.
Authorities in Latvia and Lithuania reported seizing carfentanil as an illicit drug in the early 2000s. Around 2016, the US and Canada started reporting a dramatic increase in shipment of carfentanil and other strong opioid drugs to customers in North America from Chinese chemical supply firms. In June 2016 the Royal Canadian Mounted Police seized one kilogram of carfentanil shipped from China in a box labeled “printer accessories”. According to the Canada Border Services Agency, the shipment contained 50 million lethal doses of the drug, more than enough to wipe out the entire population of the country, in containers labeled as toner cartridges for Hewlett-Packard LaserJet printers. Allan Lai, an officer-in-charge at the Royal Canadian Mounted Police in Calgary who helped oversee the criminal investigation said, “With respect to carfentanil, we don’t know why a substance of that potency is coming into our country
In 2012, a team of researchers at the British chemical and biological defence laboratories at Porton Down found carfentanil and remifentanil in clothing from two British survivors of the 2002 Moscow theater hostage crisis and in the urine from a third survivor. The team concluded that the Russian military used an aerosol mist of carfentanil and remifentanil to subdue Chechen hostage takers.
Authors of a previous paper in the Annals of Emergency Medicine surmised from the available evidence that the Moscow emergency services had not been informed of the use of the agent, but were instructed to bring opioid antagonists. Not knowing to expect hundreds of patients exposed to high doses of strong opioids, the emergency workers did not bring enough naloxone or naltrexone (the two most commonly-used opioid antagonists) to counteract the carfentanil and remifentanil and save the lives of many of the victims. 125 people exposed to the gas used in the rescue attempt are confirmed to have died from both respiratory failure and aerosol inhalation during the incident. The authors state that, assuming carfentanil and remifentanil were the only active ingredients of the knockout gas, the worst danger to the theater victims would have been apnea (loss of breathing), and that mechanical ventilation and/or treatment with opioid antagonists could have saved many lives