A global perspective on soil microplastic research: status, challenges, and suggestions

Soil microplastics (MPs) are a growing environmental concern with substantial implications for soil ecosystems, agricultural productivity, and human health. Extensive research has been conducted on the sources, transport, distribution, environmental risks, and toxic effects of soil MPs. However, research on soil MPs remains inconsistent and incomplete, and few reviews have provided a comprehensive global perspective on the key challenges in this field. In response, we compiled and analyzed baseline data from 152 studies, and conducted a comprehensive review of the literature on soil MPs. We identified key challenges in four critical areas: extraction methods, data reporting, spatial distribution characteristics, and environmental criteria. Additionally, we provided targeted recommendations: 1) establishment of standardized methods and processes for extracting soil MPs; 2) development of standardized guidelines for describing MPs and soil properties, along with an expansion of research into MP-derived pollutants and use of environmentally relevant MP materials; 3) expansion of soil MP research to socioeconomically vulnerable and ecologically sensitive regions, diverse land use types, and deeper soil layers; and 4) an approach to derive environmental quality criteria for soil MPs, based on human exposure risks. By establishing research standards and broadening the scope of soil MP studies, we aim to enhance global understanding and inform strategies for mitigating soil MP pollution.