Thread by @KeithNHumphreys

Today in @ScienceMagazine my colleagues and I address the mystery of why opioid overdoses in the US and Canada suddenly began dropping dramatically. We assemble traditional and novel evidence to point to an illicit drug supply disruption, probably in China. 1/8

Any given locality might experience a drop because say, the police took down a big drug gang, EMS got a new ambulance crew, a methadone clinic opened. But why did overdoses drop suddenly across two nations *even in places that didn’t do these things*? 2/8

First, our team analyzed U.S. drug seizures. The purity of both fentanyl powder and pills began dropping in mid-2023, and overdoses dropped in tandem. People were buying 50% weaker fentanyl by the end of 2024, and the dose makes the poison. 3/8

Second, we did something novel and looked at Reddit sublists to record how often people mentioned shortages/weaker fentanyl. There was a 14-fold spike of these conversations in mid-2023. The moderator then banned the topic, but it soon surged back 19-fold baseline.4/8

So something disrupted the fentanyl supply, but at what point in the chain? China sends precursor chemicals to Mexican cartels who process it into fentanyl and ship it north, but Canadian drug gangs process precursors themselves for domestic sale. So let’s look at Canada. 5/8

It turns out that again in mid-2023, the purity of the Canadian fentanyl supply suddenly gets volatile and then declines through 2024. Critical point: If the fentanyl supply has been disrupted in Mexico we would not have expected this to happen. 6/8

Lots of other opioid problem indicators in Canada also declined following again the pattern of the U.S. Since Mexican interdiction/disruption would not have affected both countries we look higher up the supply chain to China. 7/8

And indeed, China began warning chemical/pharma companies, closing down websites & tightening chemical controls in 2023. It is likely if not certain that China’s actions disrupted the fentanyl trade in both the US and Canada, Paper link below 8/8.
science.org/doi/10.1126/sc…