Ilaria Rosella Pagliaro Discovery in Dutch stream reveals that microplastics have contaminated even the most pristine springs since the early 1970s
©Science of The Total Environment
In the spring of 1971, an entomologist scooped a small insect larva from a clear stream in the Netherlands and placed it in a museum drawer. At first glance, it seemed like nothing unusual — a typical caddisfly larva (Ironoquia dubia), neatly tucked inside its portable shelter made from leaves, twigs, and grains of sand.
But fifty years later, a new analysis of that same specimen has completely changed the story. Hidden among the natural debris were bright yellow fragments that had no business being there. Under the microscope and using energy-dispersive X-ray spectroscopy, scientists discovered something shocking: the larva had used microplastics to build its home.
The microplastic builders
Caddisfly larvae are known for their ingenuity. They build protective cases from whatever materials they find in their surroundings. In laboratory settings, they’ve assembled homes from gold flakes, pearls, even crystal shards. In nature, though, they rely on available detritus — and that now inevitably includes plastic waste from human activity.
The specimen came from a freshwater stream in the Dutch countryside, fed by a spring — an area long considered pristine. Yet this larva’s plastic-enhanced case is now the oldest known instance of a freshwater animal incorporating microplastics into its life structure. It pushes back the earliest recorded case by 47 years, from 2018 to 1971.
Back in 1971, as the study notes, scientists were already detecting high levels of colored synthetic fibers in the North Sea. That year is now marked as the beginning of visible plastic pollution in marine environments. But this new discovery shows that the invasion had already reached the source — far upstream.
Plastic was already everywhere
The larva was collected from a spot with no visible signs of pollution: the source of the Loenense Beek, a stream that had delivered clean water to the region for centuries. But microplastics were already present, not downstream, not from sewage systems — but right at the origin.
This finding upends our understanding. It was widely believed that plastic accumulation in freshwater systems began only in recent decades. But this larva proves contamination started earlier — quietly, and deeply.
Led by Auke-Florian Hiemstra of the Naturalis Biodiversity Center in Leiden, the research team reexamined museum specimens for overlooked clues of environmental change. What they found was a plasticized fragment of history, a synthetic trail woven into the life of a freshwater insect.
It wasn’t a one-off case. Other specimens from 1986, collected near Oosterbeek, showed blue plastic fragments, likely from expanded packaging foam. These larvae, too, had combined natural and artificial materials in building their defenses.
A single insect rewrites the history of plastic pollution
It may seem like a small detail — but that larva is crushing evidence that microplastic contamination began far earlier than assumed. Today, microplastics are among the most widespread materials on Earth: found in clouds, soils, polar ice, rainfall, deep-sea sediments, and even the air on mountaintops.
And yes, they’re inside us, too. Microplastics have been detected in human blood, breast milk, and brain tissue. Some studies estimate we ingest tens of thousands of plastic particles a year. One calculation suggests we consume the equivalent of a credit card per week.
That larva from 1971 wasn’t just adapting — it was sounding an alarm. A warning we ignored for decades. If microplastics were already at the base of freshwater food chains then, they’ve only moved upward since — from insects to fish to us.
We were there. We were already plasticizing the world. We just didn’t notice.
The study was published in Science of The Total Environment.
