Adverse reactions?

NZ$ Herald has a piece today about increases in methamphetamine consumption (as measured by wastewater)

The story is about cheap meth imports increasing the supply, with a speculative aside into a decrease in consumption in Ōpōtiki and whether it might be attributable to major gang arrests.

The sudden spike in 2024 is surprising. Normally I would guess that sudden level changes in a time series were due to different definitions of the variable, but it appears to be defined the same way.

It’s obviously tempting to attribute the sudden change to the relaxation of rules on pseudoephedrine sale in 2024, and some people on social media seemed happy to do so.  There are problems, though.

First, the suddenness is still strange. You’d expect the gangs to take a while to ramp up production and sale after years out of the business — and if they were ready on day one, the spike would have been in June rather than July.

Second, that’s a big spike.  There’s about gram and a half of pseudoephedrine in a pack of decongestant tablets, which will make under a gram of meth, so a 20kg jump in meth production is a lot of Sudafed: tens of  thousands of packets per week of a drug sold only by pharmacist prescription. Someone should have noticed.

The Drug Foundation says it’s due to international supply, which seems plausible — we’re seeing  300-500kg seized most quarters recently, which is 15-40kg/week, so unless we’re catching the majority there will be enough getting through to explain wastewater levels.

The Herald also quotes price data from the Drug Trends Survey, which says prices are down. That’s a bit less supportive than it looks. First, prices were only down in roughly a straight line over several years. Second, the say they think demand has saturated, which doesn’t fit the spike. And finally, the last edition of the survey sampled from February to July 2024, so mostly missed the spike