How Soil Microplastics Affect Our Health

At DYCLE, we always refer to the recent scientific research to inform our work. In this article, we want to have a look at plastic waste and its consequenses.

When we hear about plastic pollution we immediately think about oceans with bottles, bags and other debris. But in reality, there is a silent, less visible major concern: plastic in the soil. The small plastic particles, invisible to the eye, slowly work their way from the ground into our food, water and air,  finally entering our bodies.

What Are Microplastics?

Microplastics are plastic fragments smaller than 5mm. Their origin can vary from degraded plastic bottles to fertilisers, but the one element they have in common is they do not degrade easily. Instead, they accumulate year after year. In the years soil has become the biggest reserve of microplastics on the planet, sometimes with a concentration even larger than the oceans. Nevertheless, this pollution still receives less attention.

From soil to body: how do microplastic reach us?

The main ways in which these microplastic reach us are three: food, air and water. Plants absorb microplastics through their roots. When we eat foods that are grown in contaminated fields, we also absorb the microplastic. Microplastics can also end up in ground water or be washed in water drinking systems without being completely filtered out or enter our lungs thanks to dust from the contaminated soil, for example during agricultural activities.

Microplastics are present in human body

Until recent years, the effects of microplastics on humans were mostly studied in labs. But a clinical lab report in The New England Journal of Medicine (Marfella et al., 2024) changed everything. 

Researchers studied patients with cardiovascular diseases and they found microplastics (polyethylene and polyvinyl chloride) directly embedded in people’s arteries. These are the same types of plastics commonly found in agricultural and packaging materials. The patients of the study consequently had a 4.5 times higher risk of experiencing a heart attack, stroke, or death over the next three years.

What Happens When Microplastics Enter the Body?

Microplastics have been detected in a range of human tissues,  including the lungs, liver, spleen, kidneys, placenta, blood, and breast milk. Once inside the body, microplastics damage our system in more than one way. Organs can be damaged through inflammation and stress, hormone levels can be disrupted, chemical toxins can be transported deep in tissues arriving to the alteration of DNA in worst cases. The constant exposure to these plastics might also keep our immune system triggered for a long time facilitating the insurgence of autoimmune diseases. Some studies have also shown that microplastics act as vehicles for other nocive toxins such as bacteria.

Why Soil Microplastics Are Especially Concerning

Unlike microplastics in air and water, soil microplastics can stay for decades. They are not eliminated easily, becoming a constant, long-term risk for health. In farming, plastic use is common and constant and therefore creates a compounding problem: more plastics enter the soil every year, but very little leaves.

Still, soil microplastics are not strictly regulated. Sewage sludge, plastic-covered compost, and plastic mulch films are widely used nearly without restrictions. This lack of oversight means microplastics can enter our environment and bodies almost unnoticed.

What Can Be Done?

We are just starting in the most recent years to understand what is the extent of the microplastic problem and how much of it comes from soil. The problem is already urgent enough to call for urgent changes in how we use and manage plastic. Firstly, we must regulate the use of plastics in soil and compost systems to prevent further accumulation. This includes excluding plastic mulch in agriculture and promoting biodegradable alternatives that do not stay in the environment. Additionally, microplastics in fertilizers and biosolids should be carefully monitored and limited through stricter quality controls. Finally, public awareness needs to be raised about how microplastics from soil can enter the food chain and, ultimately, the human body, people understand the health risks and take informed action.

To truly protect ourselves and future generations, we must shift our focus beyond what’s floating on the surface and begin confronting the hidden plastic pollution accumulating beneath our feet.

References

[1] Bhuyan, M. S. (2022). Effects of microplastics on fish and in human health. Frontiers in Environmental Science, 10, Article 827289. https://doi.org/10.3389/fenvs.2022.827289

[2] Marfella, R., Prattichizzo, F., Sardu, C., Fulgenzi, G., D’Onofrio, N., Mauro, C., … & Paolisso, G. (2024). Microplastics and nanoplastics in atheromas and cardiovascular events. The New England Journal of Medicine, 390(10), 900–910. https://doi.org/10.1056/NEJMoa2309822

[3] Sun, A., & Wang, W.-X. (2023). Human exposure to microplastics and its associated health risks. Environment & Health, 1(3), 139–149. https://doi.org/10.1021/envhealth.3c00053