We often hear about microplastics in our food, water, and bodies…but did you know there is also dangerous plastic pollution in the ground below us? Today, on World Soil Day, we would like to share what you need to know about microplastics in soil.
Soils serve as the literal foundation for our lives on land. Soils support the lives of animals, bacteria and other microorganisms, fungi, insects, plants, and people through essential Earth processes like cycling nutrients necessary for survival, filtering and storing water, and sequestering carbon to regulate the climate. When plastics pollute soils, they endanger soil-dwelling organisms and ecosystems, and all beings who depend on them for survival—including people.
Plastics Permeate Earth’s Soils
As we know, plastic doesn’t break down, it only breaks up into smaller pieces of micro- and nanoplastic that harm living beings and damage the ecosystems we need to survive. These tiny, lightweight plastic particles are not stationary; instead, they travel far and wide around our planet—from the atmosphere into the air, and from waterways to lands—and through our bodies. These particles and the plastic items from which they shed also leach thousands of hazardous plastic chemicals. Earth’s soils are a major sink for plastic particles and chemicals as they move throughout the environment.
Agricultural soils are hotspots for the accumulation of plastic pollution, particularly microplastics, as the use of plastic mulching, application of microplastic-containing fertilizers, and application of microplastic-contaminated sewage sludge has unfortunately become common and widespread. United Nations research suggests that agricultural soils are polluted with greater quantities of microplastics than the oceans. Scientists at Murdoch University in Australia estimate that agricultural soils now hold around 23 times more microplastics than oceans—and this number is increasing as the amount of plastics used for food production increases dramatically.
Soils in densely populated urban areas also tend to be highly polluted with plastic items and particles due to higher rates of plastic pollution. However, even forests are also accumulating significant amounts of plastic pollution, particularly in the form of microplastics—which rain, snow, and fall from the atmosphere.
Microplastics Harm Earth from the Ground Up
The presence of plastic in the ground harms the overall health of terrestrial ecosystems from the soils up. Microplastics are known to:
- inhibit plant growth and yield
- interfere with normal enzymatic activities in soils
- reduce soil microorganism biodiversity
- reduce soil porosity, reducing its ability to absorb water and nutrients
- travel deep into soils, reaching and leaching plastic chemicals into groundwater
Microplastics pose both physical and chemical hazards to organisms who play key roles in keeping soils healthy. Researchers have found that earthworms living in microplastic polluted soil experience stunted growth, which in turn stunts the growth of plants in the soils where the earthworms live. Snails, mice, and soil-dwelling invertebrates important to maintaining soil health are also harmed by microplastics. With soils and soil organisms acting as the foundation for terrestrial life, these findings are concerning and underscore how the interconnected nature of all life on Earth is harmed by plastic pollution.
Microplastics in Soil Threaten Our Food
The rise of plastic use in agriculture (plasticulture) poses particular threats to human health, as much of the food we eat is now grown using plastic. Polyethylene plastic, which is widely used as mulching to stop weeds, breaks up readily into microplastics that enter soils and plants. Research shows that the microorganisms in agricultural soils are diminished by the presence of polyethylene plastic particles: a healthy diversity of soil microorganisms is necessary to keep soils healthy. Plastic farm equipment and plastic-coated release fertilizers also send microplastics into soils, as does sewage sludge used as fertilizer—also a major source of PFAS (chemicals commonly used in plastics) polluting agricultural regions.
What’s more, plastic polluted soils send plastic particles into plants, which we in turn consume as food. While many experts suggest reducing intake of processed foods to reduce exposure to microplastics from plastic packaging, studies have found that common fruits and vegetables, including apples, broccoli, carrots, lettuce, and radishes are absorbing microplastics straight from soils. These microplastics and the chemicals they carry are entering our bodies, where they can cause serious health issues.
What’s more, plastic production and plastics themselves release climate-warming greenhouse gases. Earth’s warming is a major threat to agriculture and is a leading cause of food insecurity as it disrupts crops with extreme weather, surging temperatures, and unpredictable food yields, which disproportionately affects already vulnerable populations.
Take Action
Today, plastic particles and plastic chemicals contaminate our planet and our bodies. But we don’t have to accept a future where our world is polluted with plastics from the ground up. Tell world leaders to support a strong Global Plastics Treaty that ends plastic pollution, starting at the source by curbing and capping plastic production.
