Does sewage sludge spread microplastics in our agricultural soils and on our plates?

Every year, millions of tons of sludge from wastewater treatment plants are spread on fields as fertilizer. However, this sludge also carries microplastics—tiny fragments invisible to the naked eye that accumulate in soils and threaten crop quality and food safety.

Microplastics originate from the breakdown of plastic waste and are found in large quantities in sewage sludge. When used to fertilize land, this sludge releases billions of plastic particles into agricultural soils. Research shows that some fields receive up to several thousand microplastics per kilogram of soil, with particularly high concentrations near urban and industrial areas. These particles, often smaller than a grain of sand, can persist in the environment for decades.

Once in the soil, microplastics alter its structure and water retention capacity. They also disrupt the life of microorganisms essential for soil fertility. Plants such as rice, wheat, and corn absorb these particles through their roots or leaves. Microplastics then travel through their sap and eventually accumulate in edible parts, such as grains or vegetables. Studies have already detected their presence in plant tissues and even in certain foods.

The impact on crops varies depending on the species and the size of the particles. In rice, for example, microplastics reduce root growth and disrupt plant metabolism, which can decrease yields. They also worsen the effects of other pollutants, such as heavy metals or pesticides, by binding to their surface and transporting them deeper into the soil and plants.

Scientists are also concerned about the long-term consequences for soil health. Microplastics can clog soil pores, limit water and nutrient absorption by roots, and disrupt microbial communities. These changes affect the decomposition of organic matter and the nutrient cycle, thereby weakening land productivity.

In response to these findings, several countries are beginning to take action. Some ban the spreading of sludge containing too many microplastics, while others are developing methods to filter them before use. Research is also exploring alternatives, such as biodegradable plastics or agricultural waste recycling, to limit contamination.

However, the lack of standardized methods for measuring and identifying these particles complicates efforts to combat their spread. Current techniques, such as spectroscopy or density separation, remain expensive and inaccessible on a large scale. Without better monitoring and stricter regulations, microplastics will continue to infiltrate soils, plants, and ultimately our food. Growing awareness of this issue is pushing researchers and policymakers to seek sustainable solutions to protect agricultural land and the food chain.

Content References

Official Reference

DOI: https://doi.org/10.1007/s11270-026-09329-z

Title: Sewage Sludge-Mediated Microplastic Transfer to Agroecosystem: A Comprehensive Review on Detection, Fate and Ecological Impacts

Journal: Water, Air, & Soil Pollution

Publisher: Springer Science and Business Media LLC

Authors: Muhammad Tariq Khan; Masroor Waliullah; Zohaib Abbas; Saba Hafeez; Mohammad Bhuyan; Nasrin Akhter; Iqbal Ahmad; Asim Nawab; Mushtaq Ahmad; Yanbo Zhou; Md Faysal Hossain