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Microplastics in Agricultural Soils

Updated: Jun 11

Corn growing in soil close up

What do you think of when you think of an organic vegetable farm? Health? Purity? Nourishment? Environmental sustainability? Working with nature? These things are what most of us understand to be the values of organic farming. We’ve been told that if we eat organically, that we are eating pure foods and we will therefore be healthier than those who eat conventional produce. However, both organic and conventional farms still use plastic in their growing practices, and it is beginning to show what a colossal problem it has become. 

An alarming amount of information on microplastics affecting the environment and human health has come out in recent years. Additives in microplastics such as stabilizers, plasticizers, flame retardants and coloring agents, are endocrine disruptors. 

Now, we are discovering that one of the biggest contributors to plastic pollution in soil and water is modern agriculture. A study in 2020 published by Science of the Total Environment found a disturbing link between microplastics and harmful toxins in wheat. Residues left behind in the soil increased the concentration of phthalates in all plant tissues- roots and grains. Phthalates are known carcinogens, they are neurotoxic and are harmful to reproductive systems. This discovery highlights a serious threat to the quality and safety of our food supply. 

The same study showed that microplastics are a vector for heavy metals such as Cadmium. Soil that is more contaminated with microplastics had much higher levels of Cadmium present. If plastic can increase the levels of heavy metals in the soil, what else can it do? That question seems to have been answered by Mary Beth Kirkham, in her book “Particulate Plastics in Terrestrial and Aquatic Environments”, in which she states that microplastics are essentially soaking up everything they come into contact with, and not only the chemicals used to produce the plastic. How many times have you heard about produce recalls for E. coli and Salmonella contamination? 

Human and animal pathogens adhere to microplastics, colonize them, then transfer into developing roots and onto surface leaves. Regular washing does not remove these pathogens. It seems we are beginning to understand one of the main ways these pathogens contaminate our food sources. 

Currently, more studies and risk assessment are necessary to understand the severity of the threats that microplastics in agricultural soil pose to human health. This goes far beyond that fact that microplastics themselves end up in our bloodstreams and in every part of our bodies. While that fact alone should alarm anyone with the slightest concern for their health, we now realize we can quickly become infected by deadly pathogens simply by eating our vegetables, organically farmed or not. We might also be ingesting heavy metals and pesticides which have used microplastics as a vector to enter the plant tissues we eat. 

What can farmers do to end this massacre on the environment and on our health? They can adopt regenerative farming practices. Regenerative agriculture uses methods that work with nature to bring nutrients back into the soil, rather than depleting it. It aims to increase biodiversity and aid in recreating healthy ecosystems, often on lands where biodiversity has been obliterated by conventional agriculture. Some of the regenerative farming methods that can be quickly and easily adopted in order to reduce plastic use include using biodegradable seed-starting pots, and using organic mulching materials and cover crops instead of plastic sheeting. Research and public awareness around microplastics in farming must continue to increase until we come to a place where it is universally recognized that plastic should never be an option in agriculture.

Biodegradable plant pots with herbs on white background


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