Biodegradable plastics in soils: sources, degradation, and effects

Biodegradable plastics (BPs) are increasingly marketed as sustainable alternatives to conventional plastics, yet their environmental impacts on soil ecosystems remain uncertain. Attention to plastic-related policies, global treaties, and initiatives assessing industrial sustainability are growing, and thus there is an urgent need for scientific data on the life cycle of BPs in soils to determine their viability as a truly sustainable alternative. BPs enter soil through agricultural applications, waste disposal, and landfills, undergoing complex degradation processes influenced by soil properties, environmental conditions, and polymer characteristics. However, the release of degradation by-products, including potential toxins and microplastics, raises concerns about soil health and plant growth. Furthermore, discrepancies in biodegradability claims and the lack of standardized assessment methods hinder the reliable evaluation of BP sustainability. To ensure the environmental viability of BPs, rigorous long-term studies and standardized testing protocols are necessary to validate their degradation, <i>in situ</i>, under environmentally relevant soil conditions. Without robust scientific evidence demonstrating the safe and effective degradation of BPs in soils, the expansion of their production and investment in these materials may be limited. This review highlights the urgent necessity for integrated approaches to support effective BP assessment, to bridge scientific research, industrial deployment, and policy frameworks, which are beneficial for mitigating potential unintended environmental consequences and achieving the relevant UN Sustainable Development Goals (SDGs).