STUDY ANALYSIS: Insects and Microplastics in the 1970s

This study provides important historical data about the plastic crisis

A new study reveals that insects were incorporating microplastics into their casings over 50 years ago, providing important evidence about the historical dimensions of the plastic crisis. For a full primer on microplastics, read my essay, “The Microplastic Menace.”

Plastics have been around, in various forms, for more than a hundred years, but when it comes to plastic pollution, and in particular microplastics, we don’t actually have much of a concrete historical sense of the trends in exposure among organisms: when—followed by the related questions how and why.

We can simply assume—rightly, I think—that microplastics have been around for as long as plastics themselves, since all plastics degrade and plastics have been entering the wider environment and degrading there for a long time. But that doesn’t get us any closer to understanding exactly how much or when exposure really started to increase, or how and why.

Again, we can simply assume: the problem has always been getting worse. Volumes of plastic produced and volumes entering the environment have only increased, so even in the absence of hard data we can just assume that exposure levels have increased and mirror fairly closely the amounts of plastic that exist in the world. It stands to reason.

Still, it’s good to have actual historical data, and there are plenty of places to find them, if you know where to look. One source of data on microplastic levels in the environment is museum collections.

In today’s study, which is now online ahead of publication, researchers looked at historical specimens of caddisfly larvae taken from a Dutch museum.

In 2018, it was discovered that caddisfly larvae—which build their hard casings from whatever they have to hand, whether that’s sand grains and small rocks or organic material like bark—were incorporating microplastics into their casings.

It’s highly unlikely this began happening in 2018, so the researchers wondered whether there might be historical evidence for just how long this had actually been taking place. They went to the Naturalis Biodiversity Center in Leiden, the Netherlands, and looked at their extensive collection of caddisfly samples, dating back to the middle of the twentieth century.