Strategy towards producing relevant and reliable data for the hazard assessment of micro- and nanoplastics in agricultural soils

Micro- and nanoplastics (MNPs) are widespread emerging contaminants with many potential direct and indirect effects on soil ecosystems. Ecological soil MNP hazard assessment is thus crucial for a proper risk assessment and the development of environmental protection regulations. However, current hazard assessment testing approaches are hampered by the absence of guidelines, harmonization, and standard reference materials. This article discusses the need for improving testing approaches and provides specific recommendations to increase the relevance and reliability of ecotoxicity data. Our recommendations focus on environmentally relevant experimental designs, guidelines for microplastic test materials selection and characterization, analysis of MNPs and additives in soil and biota, and a proposal for relevant soil physicochemical properties to be assessed during ecotoxicity testing. This article brings novelty to the field of ecological hazard assessment of MNPs in soil by providing solutions and specific recommendations much needed in this field.