Wastewater analysis is a way to monitor drug use at the population level without conducting research on individuals. THL has monitored the drug situation in Finland using wastewater samples for more than ten years. Today, THL’s national wastewater analysis covers more than 60 per cent of Finland’s population. The results provide a broad and up-to-date picture of changes in drug use patterns.
Sewage samples reflect population-level behaviour
In wastewater analysis, samples are collected from wastewater treatment plants across Finland. Composite samples are taken from untreated wastewater over a 24-hour period, reflecting drug use among the entire population of the area.
"In the laboratory, drugs or their metabolites produced in the body when substances are used are measured from the water. This provides information on which substances are used in the area and in what quantities," says Aino Kankaanpää, Development Manager.
The method does not identify individuals or reveal who has used which substance.
Results are reported at city or regional level and adjusted to population size, enabling the monitoring of regional differences and trends over time.
A comprehensive picture of the drug situation through combined data
Traditional research methods – such as surveys or crime statistics – do not provide a complete picture. Not all users participate in surveys or know which substances they have used, and crime statistics only reflect part of reality.
Wastewater analysis complements this overall picture by providing representative and objective measurements of the quantities of drugs used.
"The results help different actors assess and target resources for substance use treatment and preventive substance use work. When data are collected regularly, it is possible to identify not only long-term trends but also whether observed changes in drug use are permanent or temporary," says Teemu Gunnar, Leading Expert.
"For example, if the concentrations of a particular substance in wastewater increase rapidly, this indicates increased use or the spread of new substances. This provides an opportunity to respond before problems appear in other statistics."
Information to support decision-making and research
The results of wastewater analysis are published regularly and are used to support both national and local decision-making.
The data can be used to assess how drug supply and use change in response to factors such as legislation, the economic situation or international trends.
According to Gunnar, the method is also cost-effective: when a single wastewater sample contains information from tens or even hundreds of thousands of people, it provides a broad perspective with relatively little effort.
The results complement other data sources and help form a realistic picture of the drug situation in Finland. International comparative studies also make it possible to compare regional trends with those in other countries.
New methods provide new insights
THL is currently developing new approaches to generate even more comprehensive information from wastewater analysis.
In the future, wastewater analysis methods may be able to detect new psychoactive substances more effectively, or for example bacteria resistant to antibiotics.
Wastewater analysis has become an established and important part of monitoring drug use in Finland. It helps to understand the phenomenon and provides decision-makers, law enforcement authorities and preventive substance use work with information that cannot be obtained elsewhere.
Drugs – Population-level use by region
Wastewater analysis provides an effective tool for examining changes in the drug situation.