Worms no longer thrive in micro-plastic soil, as new research has shown, and this reinforces evidence of the impact of increasingly common pollutants on the natural world.
The rosy earthworm, Aporrectodea rosea is one of the most abundant species in temperate regions. The scientists found that worms that were loaded for 30 days with high density polyethylene (HDPE), a plastic common to bags and bottles, lost about 3% of their body weight compared to a control sample of similar worms found in similar soils without Polyethylene were HDPE, which gained 5% body weight over the same period.
Bas Boots, an associate professor of biology at Anglia Ruskin University and lead author of the study, said the specific reasons for the observed weight loss were not yet clear, but may be due to the effects of microplastics on digestion of worms. "These effects include constipation and irritation of the digestive tract, limiting nutrient intake, and reducing growth," he said.
If microplastic greatly inhibits the growth of earthworms, it could affect soil health and agriculture, as worms are an integral part of the arable land ecosystem.
The study, published in the journal Environmental Science and Technology, complements a growing body of research into the effects of microscopic plastic particles on invertebrates and fish. Although it is still too early to draw conclusions about the effects on human health, studies have shown that aquatic lugworms and possible effects on fish and molluscs are harmful.
In tap water, the seas around the world, microplastics were found in chairs, in the air and in a variety of other environments.
In many places, a large number of microplastics are likely to be found in soils that are deposited there because they are present in sewage, water and air. However, the extent of contamination is largely unknown, although European studies report between 700 and 4,000 plastic particles per kilogram of soil in some agricultural areas.