New Delhi: Researchers investigated how microplastics move through earthworms, to better understand how the small particles can move from the digestive
system to other body tissues, where they can persist and cause long-term harm. Microplastics are tiny flakes of plastics that are shed by clothing, paints and cosmetics, with as much as 40 million tonnes of microplastics released into the environment every year, globally. The researchers tracked how microplastics move through earthworms, as earthworms play a key role in improving soil health, and are also considered a good indicator of what happens when living organisms ingest microplastics.
The researchers placed earthworms in soil that was saturated with microplastics, at levels far in excess of what they could be exposed to in the environment. The microplastics ranged in sizes from five to 20 microns, smaller than a human red blood cell, and were made from polyethylene, one of the most common plastics in the world. The microplastics were also coated with barium, that allowed X-rays to observe the distribution of the microplastics within the bodies, where they appear as bright, white particles.
The results of the experiment
The scientists found that the earthworms quickly ingested microplastics in the soil, reaching a consistent level in their systems over a period of about two weeks. When the earthworms where then transferred to clean soil, the earthworms were able to eliminate almost all of the accumulated microplastics within a single day, indicating that the particles did not accumulate in their bodies. The researchers mapped about 2,500 individual microplastic particles within the earthworms, that showed that the particles remained within the gut and did not cross over into internal tissues. The ingested plastics easily pass through the body, and move through the earthworms. At least the digestive systems of earthworms do not allow the microplastics to move into the body beyond the gut. A paper describing the research has been published in Environmental Toxicology and Chemistry.
