Environmental Fate and Risk Assessment of Biodegradable Polymer Intermediates

The increasing demand for biodegradable plastics and the expansion of their applications have led to their use in agriculture to replace conventional mulch films. However, our understanding of the environmental impact of biodegradable polymers during degradation, particularly the ecotoxicity of degradation intermediates, remains a limiting factor. In this study, Lactuca sativa was grown using hydroponics, and monomers which are degradation intermediates were added to the nutrient solution to evaluate phytotoxicity. Biodegradable polymers are assumed to pass through a monomer stage before being converted into final inorganic products. Based on this, five monomers were selected and experiments were conducted under controlled conditions. To confirm whether lettuce absorbed the monomers, isotope ratio mass spectrometry was used to analyze changes in isotope ratios. Additionally, plant growth indicators such as biomass accumulation, number of leaves, and root elongation were monitored to evaluate toxic effects. The results showed that toxic effects varied significantly depending on the monomer type, demonstrating that structural differences in biodegradable polymers play a decisive role in environmental safety. While certain monomers exhibited distinct growth inhibiting effects, others had minimal impacts, suggesting that not all biodegradable polymers pose the same environmental risks. Furthermore, isotope analysis revealed distinct absorption pathways for different monomers, providing insights into how degradation products interact with plant systems. This study went beyond a simple assessment of biodegradability to systematically elucidate the impact of biodegradable polymers on real world agricultural systems. These findings demonstrate environmental efficacy and provide foundational data for considering toxicological risks when designing biodegradable materials for agricultural use.