Earthworms lose weight in plastic-filled soil

When the earthworms are in trouble, we all are.

An interesting new study, published in the journal Environmental Science and Technology, has looked at the effect that microplastics in the soil have on earthworms. Researchers from Anglia Ruskin University in the United Kingdom compared soils contaminated by biodegradable polylactic acid (PLA), high-density polyethylene (HDPE), and microplastic clothing fibres (acrylic and nylon), as well as clean soil without any of these additives.

Over a period of 30 days, rosy-tipped earthworms (Aporrectodea rosea) living in microplastic-contaminated soil lost on average 3.1 percent of their bodyweight. In the same amount of time, those living in clean soil gained 5.1 percent. The precise reason for why this happened is not clear. Lead study author Dr. Bas Boots said in a press release,

“It may be that the response mechanisms to microplastics may be comparable in earthworms to that of the aquatic lugworms, which have been previously studied. These effects include the obstruction and irritation of the digestive tract, limiting the absorption of nutrients and reducing growth.”

The researchers also planted rye grass (Lolium perenne) in the different soils and found that fewer and smaller shoots grew in the contaminated soils.

The evidence is piling up that plastic is not good for life forms of all kinds, and the fact that it's harmful to earthworms is particularly distressing, as these humble dirt-dwellers are crucial players in the circle of life. Their subterranean pathways bring oxygen to plant roots, and their gargantuan appetites break down waste and generate rich compost.

Without earthworms, we'd be in big trouble, which is yet another reason why we need to seriously reassess our lifestyle habits and pressure leaders to reduce plastic usage. But before you do anything else, please go and get your hands on a copy of Gary Larson's highly amusing children's book, “There's a Hair in My Dirt! A Worm's Story.” You'll never look at worms in the same way again.