Can wastewater monitoring help inform future drug prevention strategies?
The future of illicit drug surveillance may be coming from the flush of your toilet in a “collective urine test.”
Wastewater drug monitoring is a rapidly developing body of research and some countries, including Canada, are using researchers’ findings to shape policy and illicit drug prevention strategies.
In the largest wastewater study ever conducted, researchers from 41 international institutions as a part of SCORE, (Sewage analysis CORe group Europe) tracked drug use over seven years, from 2011 to 2017. The samples came from 120 cities in 37 countries and measured drug residue in urine from more than 60 million people.
Published in the journal Addiction in October of last year, the study aimed to demonstrate the efficiency and robustness of this methodology by standardizing sampling and analysis procedures.
But perhaps more notably, the study unveiled interesting patterns, spikes and trends in illicit drug use globally. Wastewater analysis takes the methodology we currently use to screen for drug use on an individual level and expands it to monitor and surveil an entire population.
The study identified four drug substances in wastewater — amphetamine, methamphetamine, ecstasy and cocaine. Regional variations of drug use were significant. Iria González-Mariño, the co-lead on the study and professor of chemistry at the University of Salamanca in Spain, says she was surprised by the high levels of cocaine in the Spanish city of Santiago de Compostela. This trend was true across Europe, where cocaine use appears to be rising.
Meanwhile in Canada, Viviane Yargeau, chair of the department of chemical engineering at McGill University in Montreal, who led the Canadian wastewater analysis for this study, says she was surprised by the levels of methamphetamine use. “We see there’s a clear preference for that drug in Montreal as a metropolitan area compared to Europe, the U.S. and other places,” she says.
The researchers’ surprise indicates that such changes in drug use have not been captured through other drug surveillance methods. “This becomes valuable information for decision makers or people designing intervention strategies,” says Yargeau.
González-Mariño says this analysis can be done “almost in real time.” This is a significant time-saver, given that traditional methods of drug surveillance have relied on time-consuming and expensive surveys, which also have inherent bias.
Alternatively, data can be gathered through hospitalizations, rehab check-ins, law enforcement drug seizures and even deaths. But these options are limited and do not tell us what drugs are being consumed right now, at least not until it is too late for an effective prevention campaign to intervene.
This is why countries have begun adopting wastewater drug analysis into their formal data collection agencies, including Statistics Canada, and for policy making. Leading the way is Australia, where the National Wastewater Drug Monitoring Program is funded by the Australian Criminal Intelligence Commission and has been in place since 2016.
Kevin Thomas, who leads the research for this national program out of Queensland University and is the co-founder of SCORE, says his team “covers 55 per cent of the Australian population, around 13 million people, and 52 wastewater treatment plants.” The program is able to track illicit drug use in addition to nicotine, alcohol and opiates, which, Thomas says, “sets us apart from a lot of other countries collecting.”
The data gathered in Australia is used to shape policy and provide intelligence to look at the effectiveness of various prevention programs. With a more comprehensive picture of the country’s drug use, and level of harm for each drug type, more targeted education campaigns have been created and vital drug use information is being provided to health authorities. The effectiveness of drug seizures in relation to the national demand of each illicit drug can also be better measured using wastewater data. This could be the future for Canada as well.
Yargeau partnered with Statistics Canada to track cannabis use before and after its legalization, using 14 wastewater treatment plants in five cities. In addition to cannabis, the pilot project tracked cocaine, methamphetamine and opioid use. Yargeau says Statistics Canada was quite happy with the effectiveness of this study, in terms of its efficiency in both cost and time, and that they intend to continue the research.
Many researchers in the field are also eager to expand wastewater monitoring to other areas of public health analysis. “If you go through all that effort of collecting samples and sending them to a lab, why not look for other indicators of health?” asks Yargeau.
Thomas says his team is already starting to monitor the health of populations using wastewater. “We can look at allergy burdens, for instance, in cities to see whether that correlates with weather events.” Such as changes in humidity, temperature and even wind.
Yargeau says they could also look at medication use and proteins found in wastewater to indicate the health of a population and its disease burdens. Surviellence can go beyond illicit consumption to look at a populations’ use of, or exposure to, substances including alcohol, nicotine, caffine and even artificial sweeteners. Further, exposure to environmental and food contaminants can also be traced through the presence of pesticides, parabens and ultraviolet radiation.
However, the methodology does not come without its challenges.
One source of uncertainty is in making sure the samples collected are representative of a population. Thomas says this requires comparing wastewater to census data to determine how many people actually live in the area. They also use mobile phone tracking data to see how many people are in a catchment at any given time.
There is also the risk of spikes due to drug dumping, tourist season and false positives from some common medications such as Vick’s vapor inhalers. Such medications have a drug called levomethamphetamine which is a lawful component of methamphetamine and can therefore set off alarms for illicit drugs. Thomas also says they can actually tell whether or not a drug has passed through the human body to avoid including drug dumps in their sampling. As well, researchers can determine how the drugs were manufactured to see whether or not they are pharmaceutical medications by examining the compounds present in the drug through an immunoassay screening test.
While researchers have reached a point where they are fairly confidencet in their sampling analysis, some members of the public are concerned about their privacy. This is a real risk, according to Thomas, who says there is an “issue of stigmatization which leaves people vulnerable in that their community has been identified as being associated with drug use.”
This has even led some cities to refuse wastewater analysis to avoid being labelled as a hotspot for illicit drugs.
Thomas is trying to minimize this problem by anonymizing his data at the national level in Australia and is encouraging other researchers to do the same. SCORE has set out ethical guidelines aimed to “minimize risks for vulnerable people and other groups and help maintain the good reputation of the field.”
When conducted ethically, Thomas believes this practice can be “totally noninvasive.” And the people he has spoken to agree that it makes sense. “If this is what we do to understand if an individual’s been taking a drug, why not do it for an entire community?”
Natasha Comeau is an international development expert who specializes in global health. She is a fellow in global journalism at the Dalla Lana School of Public Health.