Toxicological Effects of Micro and Nanoplastics on Soil Fauna: Current Research, Advances, and Future Outlook

Microplastics and nanoplastics (M/NPs) are ubiquitous in soil environment because of agricultural, industrial, and waste management activities. They can spread and age in soil due to the physical, chemical, or biological factors related to soil and plastics. Their fate in soil environment mainly depends on their adsorption capacities to soil and other contaminants. Their spread, aging, and fate in soil determine their bioavailability for soil fauna. Bioavailable fraction of micro and nanoplastics is partitioned into terrestrial organisms based on the toxicokinetics principles. Although the toxicodynamics of M/NPs, including at cellular and organism levels, has been studied relatively commonly, their toxicodynamics at the macromolecular level and toxicokinetics have not been investigated properly, yet. Moreover, the mixture of toxicological effects of M/NPs with other emerging contaminants and heavy metals is still in its infant stages in the literature. These studies should be advanced with mechanistic understandings in order to make contribution to environmental risk management of M/NPs. As a future outlook, the toxicity of M/NPs may need a different insight when the circular economy principles will be adopted widely and released M/NPs may have unusual characteristics due to the shift in waste management.