Something in the water
Yesterday, the Police released the first data from the expanded program of wastewater drug testing they have been doing with ESR (more detail). There’s a report at Stuff (from the Dominion Post).
The data are estimated total consumption of various drugs by the people using various parts of the sewer system in New Zealand. There’s obviously quite a bit of uncertainty, but it’s probably a useful guide. Because they’re measuring metabolites, not the original drugs, they are less likely to be misled by drugs discarded without being consumed — but they are probably more sensitive to differences in metabolism between people. The analogue for tobacco and alcohol is the data on total amount sold, which is a widely used statistic because it’s thought to be more accurate than self-report.
The headline figure is an estimated 16kg of methamphetamine used per week. So, how does this compare to other estimates? The story at Stuff has part of the calculation, showing about 1000 mg per day per 1000 people in the highest-testing areas, and a national average of about 600 mg/day/1000 people. If NZ survey-based statistics are accurate, perhaps 2 people per 1000 will be regular users, so we’d be looking at 300mg/user/day. That’s a lot, but it’s within the range that Erowid lists for chronic users. So, probably the surveys are underestimating the number of users, but not by a factor of ten or anything like that.
As Russell Brown says in his analysis of the report (which you should definitely read), one of the important findings is that total meth use seems to be pretty constant day to day, unlike MDMA use, which peaks at the weekend. That’s consistent with a subset of regular users taking it daily or most days. One of the limitations of wastewater testing is that the social impact of a drug doesn’t just depend on the total community consumption, but combining the wastewater data with other data is helpful.
The comparison of fentanyl to the other drugs is confounded with the higher potency of fentanyl — something it’s unusual for the media to gloss over. If we go by the therapeutic dose of fentanyl for post-operative pain, 50-100 micrograms, there are about as many doses in the 3g of fentanyl reported per week as in the 4kg of MDMA. On the other hand, the 3g does include prescription use, and people who were dependent on the drug would likely take higher doses and multiple doses per day.
Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »
The Police say :
“Average weekly use of the detected drugs has an estimated street value of $9.6 million. This is estimated to generate approximately $500 million of criminal profit annually. ”
Isnt that the turnover , not the ‘profit’.
The detail of the testing says:
‘baseline of what consumption looks like among the population covered by the Auckland, Christchurch and Whangarei sites.’ ( 2018)
the Auckland site mentioned is Rosedale, essentially only the North Shore but excludes Hisbiscus coast.
The Auckland (Rosedale) samples represent a population estimate of 240,000 people,Christchurch samples represent a population estimate of approximately 360,000 people,Whangarei samples represent a population estimate of approximately 47,000 people
All up its 650,000 urban area people and say 13% of a population of 5 mill.
Thats 3 locations, yet they feel confident to mention other regions and Russell Brown gets excited about
“Meth use was lowest in Queenstown (25%), where use of cocaine and MDMA was high. (The only site that registered higher for cocaine use than Queenstown was Moa Point in Wellington, which is either people hoovering up the last of their coke before getting on a plane or some sort of Wellywood business.)”
Which tells us that he doesnt know that Moa Pt is the ocean discharge point for all of Wellington and Hutt Valley ( they dont have treatment plants)
Where is the data for the regions outside the 3 mentioned.
5 years ago
The three sites covering 13% of the population was before the expansion (I linked to it because it’s got details about how they did the measurement). They have a lot more sites now.
I agree on the ‘social cost’ and ‘criminal profit’ thing: it’s not all profit and not everyone is paying street price. However, some of the costs for one person in the chain are someone else’s profit — we need sort of the opposite of “value added”
5 years ago