Flush with data
January 2, 2019 1:10 PM   Subscribe

Statistics Canada is measuring cannabis use by sampling wastewater in five Canadian cities. In the first data release, Halifax has come out on top. The Canadian pilot study is one example of research being carried out in the burgeoning field of wastewater-based epidemiology.

Wastewater-based drug epidemiology explained (2:15)

Wastewater Epidemiology: Real-time Public Health Research:

Wastewater epidemiology has several advantages as an information source. A major pro is that it’s anonymous–yet it’s able to capture a little bit of data from a wide cross-section of the population. Depending on the wastewater treatment facility size, upwards of a million people could be represented in a single day. Additionally, screening for drugs that pass through the body and enter the sewer system may be one of the fastest, most accurate ways to assess a community’s drug-related behavior.

Dr. Prasse highlighted that wastewater epidemiology might provide insight into the chemicals that we are exposed to through tap water, food, and products we use. For scientists using wastewater epidemiology to study exposure he said that “the important part is to monitor specific biomarkers in the water (such as metabolites of pesticides or pharmaceuticals that are only formed in the human body). By analyzing these biomarkers you can ensure that humans have been exposed and they are not originating from other sources.”

Finally, wastewater epidemiology offers (almost) immediate results. This is very different than typical surveys and data collection that often have substantial lag times before information is made available.

While the study of sewage is inherently anonymous (as everyone’s excreta gets mixed together in wastewater), there are still concerns about privacy. An individual’s anonymity is generally not an issue, but how it affects smaller areas of the city can be of concern. Certain areas fear stigmatization if a non-zero amount of any drug shows up in their wastewater–particularly since wastewater can help track illicit drug use. Researchers need to ensure that their research is ethically conducted and does not endanger vulnerable groups–like students, schools, or prisoners.


Wastewater-based epidemiology, an analytical chemical approach for the investigation of human consumption of lifestyle chemicals:

The research presented in this thesis supports the hypothesis that wastewater-based epidemiology (WBE) approach can be used as an alternative and non-intrusive technique that provides information about a population’s health and lifestyle habits.

Latest data reveal drug-taking habits in close to 60 European cities:

The latest findings from the largest European project in the emerging science of wastewater analysis are presented today by the Europe-wide SCORE group, in association with the EU drugs agency (EMCDDA). The project analysed wastewater in 56 European cities in 19 European countries in March 2017 to explore the drug-taking behaviours of their inhabitants.

From Berlin to Vilnius and from Helsinki to Barcelona, the study analysed daily wastewater samples in the catchment areas of wastewater treatment plants (WWTPs) over a one-week period. Wastewater from approximately 43 million people was analysed for traces of four illicit drugs: amphetamine, cocaine, MDMA (ecstasy) and methamphetamine.
posted by mandolin conspiracy (17 comments total) 27 users marked this as a favorite
 
A major pro is that it’s anonymous

Upstream swimming sniffy snake robot. Problem solved. :[
posted by sexyrobot at 1:23 PM on January 2 [1 favorite]


Vancouver had the lowest average of the five cities sampled, at 288 micrograms per person a week.
Canadian stereotype goes boom.

It's probably because they don't have any money left over for weed after they pay the rent.
posted by clawsoon at 1:27 PM on January 2 [27 favorites]


This is pretty interesting. I wonder: would be legal, either in Canada or in the US, for wastewater samples to be taken from a single street block with maybe only 10-12 houses on it?

How about a single apartment building? What about a single house?

I’m reminded that in many venues, the authorities cannot search your trash bin without a warrant, but if they wait until it’s dumped into the garbage truck or a community bin, the presumption of privacy goes away and they can look through it without a warrant.

It would be a way to pick up on drug abuses, narrowing them down by neighborhood, then apartment buildings, etc.
posted by darkstar at 1:40 PM on January 2 [1 favorite]


Literal piss-takes. Off to a fine start 2019!
posted by srboisvert at 1:40 PM on January 2 [3 favorites]


More like wasted-water epidemiology, eh?
posted by blakewest at 1:41 PM on January 2 [4 favorites]


The first flush of data has been released from a unique pilot project that aims to measure Canadians' marijuana consumption through their sewage, and the results are murky.

^ Needs more ASCII puts-on-sunglasses meme.

It's interesting stuff to be sure, but the uncertainty in the final consumption estimates is huge. I'm not sure it's really going to be useful for estimating the size of the black market, when the amount of product in tons-per-year is somewhere between 300 and 1900 tons (depending on the estimated potency of product and also the two scenarios of THC excretion rate). Hopefully they can tighten it up over time and with more samplings—it says the numbers are expected to "improve substantially".

I suppose if the numbers are at least consistent and proportional, there will be some interesting data as the legal recreational market grows. E.g. if the metabolites in sewage stay constant, we could probably conclude that people are moving over from the black market to the legalized one, and if they're different, it might provide a clue as to the size of the black market if we know the additional new consumption on the legalized side. (Though if legalization leads to more people just buying from the unregulated market, that might not be a reliable indicator.)

It appears that Canada is aiming for a much lower tax rate (around 10%) than some places in the US have attempted to impose, with entirely predictable consequences and a failure to eliminate the black market as a result. I'm hoping, perhaps naively, that the data they're collecting will inform future legalization initiatives in the US as well. (California having helpfully provided us with an example of how not to do it...)
posted by Kadin2048 at 1:41 PM on January 2 [4 favorites]


More like wasted-water epidemiology, eh?

I was trying to work a bongwater joke into the title but couldn't quite stick the landing.
posted by mandolin conspiracy at 1:45 PM on January 2 [3 favorites]


This is pretty interesting. I wonder: would be legal, either in Canada or in the US, for wastewater samples to be taken from a single street block with maybe only 10-12 houses on it?

Well - there is a school of thought that says once something becomes "waste", it is free to be investigated for statistical/law enforcement purposes... (at least this is what a lifetime of TV media with detectives and crime scene investigators has "taught" me)...

... But, in terms of Cannabis use for overall population... in Canada, it really doesn't matter anymore, it is legal and available across the country... Perhaps, if a government bases their policies on science, they could use similar studies in countries where it is not legalized, to find that it is being used in the population anyways - and should be legalized... (ha... yeah, I am thinking the reality is more likely used for policing of certain communities)
posted by jkaczor at 1:46 PM on January 2 [1 favorite]


It's interesting stuff to be sure, but the uncertainty in the final consumption estimates is huge. I'm not sure it's really going to be useful for estimating the size of the black market, when the amount of product in tons-per-year is somewhere between 300 and 1900 tons (depending on the estimated potency of product and also the two scenarios of THC excretion rate). Hopefully they can tighten it up over time and with more samplings—it says the numbers are expected to "improve substantially".

Yeah, as you point out it's not really the absolute value as much as the trend that is important; there seem to be three major sources of uncertainty: in addition to the potency and the excretion rate, whatever environmental conditions affect the measurement on the way from the, um, source to the treatment plant. The population-level excretion rate seems like it should be stable (unless demographics shift substantially?), and the environmental conditions should also be relatively stable.

The potency may change over time, but in a way this is a feature not a bug -- alcohol consumption is often normalized to take into account the different strengths of wine/beer/liquor. If people smoke a little less weed because it gets way more potent, this would track the actual amount of drug being administered, not the amount of plant consumed.
posted by Homeboy Trouble at 2:13 PM on January 2 [1 favorite]


Upstream swimming sniffy snake robot. Problem solved. :[
posted by sexyrobot at 4:23 PM


Paging Dr. Cronenberg to the Body Horror department.
posted by mandolin conspiracy at 2:13 PM on January 2 [7 favorites]


It appears that Canada is aiming for a much lower tax rate (around 10%) than some places in the US have attempted to impose, with entirely predictable consequences and a failure to eliminate the black market as a result.

I'm confused by this; can you elaborate? My initial (perhaps naive) thought would be that a lower tax rate, although it might not be the best decision for other reasons, would encourage people to move away from the black market.
posted by Expecto Cilantro at 3:38 PM on January 2 [2 favorites]


I'm happy to have a septic tank.

As far as the black market goes, my thinking about how legislation in Vermont went has changed. I thought at first it was stupid to legalize pot but not the sale of it. After the fall harvest, I thought the bottom must have fallen out of the black market. Everyone I know who uses pot has gotten free pot from home growers.
posted by MtDewd at 4:39 PM on January 2 [2 favorites]


Halifax has come out on top

I am Jack-the-ex-Haligonian’s total lack of surprise.
posted by ricochet biscuit at 5:46 PM on January 2 [4 favorites]


would encourage people to move away from the black market.

Depends. A high tax rate PLUS draconian enforcement against black market material could reduce illicit activities and reduce overall use.

A high tax rate plus selective enforcement can be spun to seem to show that legalized Cannabis has no effect on the illicit market and that draconian enforcement should be considered instead of legalization/ regulation.

A reasonable tax rate - to support testing, quality assurance, inspection, and education - plus reasonable enforcement against black market material is probably the most neutral path to attempt.

Depends on what you're intentions are.
posted by porpoise at 8:25 PM on January 2


wrt Vancouver having lower than expected values, well, there are a lot of people in Vancouver - many of whom aren't actually here.

The higher Asian/ South Asian population also contributes to a more bimodal distribution of users. Yes, there are many open heavy users but there are also a lot more non-users/ not-present potential users.

I'm with a federally licensed Cannabis company in the Vancouver area and it's about 15% regular users, 15% occasional users, another 35% have ever used, and the remaining 35% are (seriously) "have never used."
posted by porpoise at 8:33 PM on January 2 [1 favorite]


My initial (perhaps naive) thought would be that a lower tax rate, although it might not be the best decision for other reasons, would encourage people to move away from the black market.

That's what I meant; the placement of the comma in that sentence was unfortunate. Mea culpa.

I was referring to the very high excise taxes imposed by some US jurisdictions on recreational cannabis, in particular the effect of those high taxes, which has (based on most analysis I've read) been to keep the black market around. Canada seems to be shooting for something in the neighborhood of 10%, and a price of $10/gram, significantly less than CA (and most other US states I believe). That, I'd imagine, will make significant inroads against the unregulated market in a way that California has failed to.

I think regulators in the US have consistently overestimated the "risk premium" associated with the unregulated/illegal market. People who are already buying from a dealer are unlikely to suddenly pay 30% more to shop at a store, it would seem. And the shortage of stores is preventing the recreational market from expanding to other consumers who wouldn't purchase from the black market.

To get rid of the unregulated market, you need accessible product at a comparable price. Canada seems to be on a better path, and I'm particularly impressed that they're doing mail-order sales.
posted by Kadin2048 at 12:27 PM on January 3 [2 favorites]


News from Canada: My provincial Conservative government was complaining on the radio the other day that Justin Trudeau's federal government is failing to provide them with enough weed to distribute.
posted by clawsoon at 7:40 AM on January 8


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