Needless to say, alcohol is considered one of the most lethal recreational drugs – the World Health Organization attributes over 3.3 million deaths a year to the liquid substance that is legal in most countries. To put that into context, that’s nearly 6% of all global deaths and more startlingly yet, 61.7% of the population don’t even drink alcohol, meaning a more concentrated level of drinking among less than half the world. These WHO findings might present the big picture, but since the report is based on country-level analysis, using qualitative interviews and sales figures as the basis of the study, they might not present an actionable nor targeted outcome. “Such information has been traditionally obtained from sales statistics and population surveys that require additional data due to their limits to cost- and time- effectiveness, representativeness and accuracy,” reads the introduction to a new study led by Yeonsuk Ryu of the Norwegian Institute for Water Research. Looking to find more accurate, timely and geographically-specific data on alcohol consumption, Ryu and a network of colleagues across 20 cities in 11 countries have been testing the waterwaste to find out just how much alcohol urban populations consume… By figuring out just how much they excrete.

wastewater alcohol drinking

A waterwaste treatment plant in Dresden, Germany. Photo couresy of Stadtentwässerung Dresden GmbH.

“The accurate and timely assessment of alcohol consumption is necessary for maintaining and improving the quality of health care. The quantitative analysis of specific biomarkers in wastewater, produced following the consumption and excretion of drugs, is a complementary approach for estimating the levels and trends of drug use by a population in a specific sewer catchment area,” explains the original research paper published in Science of The Total Environment. “Compared to sales figures and general population surveys, the data source for this approach (wastewater) is readily available and feasible to provide reliable information almost in real-time.”

Waterwaste-based epidemiology (WBE) methods for tracking drug use are not new approaches. Previous studies have found that cocaine and ecstasy use increase on weekends in London, while methadone levels remain pretty stable all week-long; in Zagreb, heroin and marijuana are the drugs of choice and, on campus at University of Puget Sound in Tacoma, Washington, amphetamine spikes are noted during final exams. However, given alcohol’s legal status in most countries, the need to conduct covert experiments to gauge the level of drinking has seemingly been overlooked. In fact, Rye’s experiment is the first multi-city international report on the comparative measurement of alcohol use through WBE.

The science behind WBE for alcohol detection is pretty simple: Raw 24 hour composite wastewater samples were collected for a week from 23 wastewater treatment plants in the 20 cities covered for the report. With these samples, the researchers tested for ethyl sulfate (EtS) which is “a metabolite of ethanol that indicates the recent consumption of alcohol with detection times up to 48 hours in healthy volunteers and is stable in wastewater.” The amount of EtS is calculated taking into account excretion rates and the daily flow of wastewater, as well as the local population being served by the treatment plants in questions, helping calculate alcohol consumption. Meanwhile, each of the cities were monitored on what the researchers called a ‘normal week’ – that is, a period of time where no special events (that could alter typical alcohol consumption behavior) occurred.

alcohol consumption cities wastewater

Estimated population-normalized daily alcohol consumption in 20 cities during the predefined sampling period (March 2014). Error bar indicates the combined uncertainty calculated (Ut). Dashed lines present the daily consumption (both recorded and unrecorded) in the corresponding country calculated based on the report by WHO (2014). aSample of Tuesday 18th March < LOQ. bn = 26 (4 WWTPs). cDifferent sampling period (February 2015). dn = 6 (sample of Wednesday 12th March missing). en = 8, different sampling period (March 2015).

The results, as seen in the graph above, show some disparities between the WHO’s 2015 country-level report (as referenced at the start of this article). While some cities’ level of EtS correlated with alcohol consumption rates as recorded on a country-level (as indicated by the horizontal dotted line), such as Amsterdam and Eindhoven, the Netherlands, Dresden and Munich, Germany, and (to a slightly lesser extent) Oslo, Norway, other cities showed a rate much higher than country averages. Copenhagen, Denmark and Granby, Canada showed extremely higher rates than the WHO country-level analysis, while residents of the two Australian cities in the study, Canberra and Toowoomba, look to have been painted with the same high-alcohol-consumption brush as their fellow countrymen, though they drink far less. Similarly low levels, vis a vis WHO’s country-based reports, were found in Lugano, Switzerland, Milan, Italy, Barcelona, Spain, Almada, Portugal, and Berlin, Germany.

“The minimum period of sampling to reveal statistically valid pictures of alcohol consumption needs to be further investigated, however it is clear that reliable results can be obtained by WBE within much shorter period than general population data that requires at least several months,” continue the report’s findings, which also found that alcohol consumption peaks (unsurprisingly so) on the weekends. Additionally, the WBE analysis looked at biomarkers for illicit drugs, namely cocaine, amphetamines, methamphetamines, MDMA and cannabis, in order to spot correlations for drugs used in tandem with alcohol. “It is important to note that such comparisons are only meant as a crude assumption since specific biomarkers of co-consumption (such as cocaethylene) are required to verify the combined use of alcohol and other drugs. Especially, the excretion rates of drugs can be affected by co-administration of alcohol, and therefore the direct comparisons of drug biomarker loads (present study) should be carefully interpreted,” warns Rye. Nonetheless, the “crude” assumptions shed light on the culture of recreational drug use in various cities. While cocaine correlated most strongly with alcohol, with positive correlations in 15 of the 20 cities studied, only 5 cities showed a high correlation between alcohol and MDMA, and only 4 between alcohol and amphetamine. “This result is in contrast with the previous study carried out in Barcelona, 2013 ,that presented strong correlations of MDMA and amphetamine with alcohol consumption,” explain the researchers.