A new study published in Ecological Applications has shown how microplastics have affected living things in the past.
Scientists at the Loyola University of Chicago have used museum collections to study the intestines of freshwater fish over the past century. The study found that fish have been ingesting plastic waste for decades since 1950. Moreover, the concentration in their digestive tracts has increased dramatically in recent times.
What are microplastics? These are small particles of plastic of any kind. The marking does not matter. In 2004, marine biologist Richard Thompson identified plastic pieces no larger than 5 mm in a separate category.
To make it clearer, imagine a handful of beads: small, plastic, multi-colored. If you scatter it around the room, you will most likely not collect all the beads. They will remain in the cracks behind the furniture. So it is with microplastics – it cannot be separated from water, soil, air. Particles of the finest fraction do not lend themselves to filtration.
Microplastic pollutes our habitat, and its final stop is human, animal, fish, bird, and insect organisms. Through them, it can be transmitted to humans. The problem of environmental pollution by microplastics became urgent right now because its amount did not raise concerns before that. Now it has accumulated and has become the cause of invisible but dangerous pollution. However, the new study authors wanted to understand how microplastics have accumulated over the past century. They used specimens of fish from the Chicago Field Museum. There, 2 million samples are stored in alcohol and in an underground collection.
Biologists focused on four types of fish: largemouth bass, channel catfish, sandstone, and round gobies. Life records for these species date back to the period from 2017 to 1900. Scientists also collected fresh samples of the same species of animals for study.
The researchers used scalpels and tweezers to dissect the digestive tract and then treated it with hydrogen peroxide. It destroys all organic matter but leaves behind any potential plastics.
Scientists have used microscopes to identify materials with suspiciously smooth edges, which could indicate microplastics. Then, in collaboration with researchers at the University of Toronto, the scientists confirmed their chemical signatures using Raman spectroscopy.
Plastics were not discovered until the middle of the last century. The amount of microplastics in the intestines of the studied fish increased dramatically with the rise in plastic production in the middle of the last century, starting in the 1950s.