Microplastics—tiny fragments of plastic less than five millimeters in size—are acting like a "Trojan horse" in soil, carrying pollutants, pesticides, and bacteria through the environment, according to a major five-year research project funded by the European Union. The project, which has generated 22 peer-reviewed studies, found microplastics in all 227 agricultural fields tested across 11 European countries. This discovery highlights a growing global concern, as healthy soil is crucial for sustaining life on Earth. The contamination was linked to both modern farming practices and historical land use, showing that plastic pollution can remain in the environment for many years. The research also revealed that microplastics can interact with other agricultural stressors such as pesticides and veterinary drugs. In one Swiss study, fields with high levels of tire-wear particles—microplastics from vehicle tires—also had high concentrations of toxic chemicals and heavy metals. These tiny plastic fragments create new habitats on their surfaces, known as the "plastisphere," where microbes and agrochemicals can interact. Researchers found that these areas had a higher presence of antibiotic-resistant genes compared to non-plastic areas. Pesticides appeared to increase this effect, making the problem even more concerning. Smaller microplastics are especially effective at absorbing pollutants, microbes, and genetic material, leading to a "Trojan horse effect" that may spread pathogens and antibiotic resistance. This effect can disrupt important soil processes, such as nutrient cycling, affecting earthworms and other soil organisms. Earthworms are key to maintaining soil health, as they influence the composition of the soil microbiome and support ecological functions. The study also found that microplastics can negatively impact plant growth, reducing leaf area, chlorophyll content, and biomass in plants like lettuce. These effects were more severe under drought conditions, showing that the combined stress of microplastics and environmental factors can be particularly harmful. Environmental assessments often look at pollutants individually, but this research shows that their combined presence can lead to different and more complex outcomes. The researchers argue that policies must recognize plastic contamination as part of a broader issue of soil degradation and pollution. While biodegradable plastics are being promoted as a solution to reduce plastic waste, the study found that they can still break down into microplastics and cause ecological harm. Dr. Esperanza Huerta Lwanga from Wageningen University emphasized the need for standardized monitoring, transparency from manufacturers, and risk assessments that consider how microplastics interact with other pollutants across various species. Protecting soil health and ensuring long-term food production require urgent policy action.