Man-made chemicals found in all soil samples collected by Danish schoolchildren

Man-made chemicals have been detected in every soil sample collected by 30,000 Danish schoolchildren as part of a nationwide science project, according to a report by Danish broadcaster DR.

The findings, released by the national science education centre Astra, reveal that industrial chemicals and PFAS—often called “forever chemicals”—were present in all tested soil from 97 of Denmark’s 98 municipalities. Only Læsø, the country’s smallest municipality, did not participate.

Researchers from Aarhus University, Aalborg University, and the Technical University of Denmark analysed the samples, collected last September as part of the annual Masseeksperiment (Mass Experiment). The project, supported by the Nordea Foundation and Villum Foundation, engages schoolchildren in large-scale scientific data collection.

“It’s a wake-up call”
Mogens Humlekrog Greve, the lead researcher and section head at Aarhus University, described the results as alarming.

“I think it’s a wake-up call when we confirm that the situation is as bad as—or worse than—we feared,” he told DR. “This is the first time we’ve systematically examined soil in urban-adjacent areas, and the findings are concerning.”

While the presence of chemicals has been confirmed, their concentrations have not yet been measured. Further analysis will determine levels of contamination.

PFAS detected in 80% of samples
The study found PFAS (per- and polyfluoroalkyl substances) in roughly 80% of the samples, alongside other industrial chemicals. These synthetic compounds, used in products like non-stick cookware and firefighting foam, are known for their persistence in the environment.

Lene Christensen, programme director for Masseeksperiment, emphasised the reliability of the data despite being collected by schoolchildren.

“The students aren’t trained lab technicians, but experience shows they gather high-quality data when given clear instructions,” she said.

Data to support EU soil monitoring laws
Humlekrog Greve noted that the findings will aid Denmark in implementing the EU’s Soil Monitoring Law, which requires member states to track soil health.

“We need to establish threshold values for soil health indicators, and this project has provided a goldmine of data we can draw from,” he said.

The Mass Experiment has run annually since 2007, engaging students in hands-on science while contributing to national research.