Solution or Pollution? A paradigm shifts in understanding the fate and threats of biodegradable plastics in the marine environment

• Microplastic pollution may result from the decomposition of biodegradable polymers • Biodegradation mechanisms of biodegradable plastics are crucial. • Biodegradation depend on plastisphere and external environmental conditions Biodegradable plastics are proven to degrade faster and are thus presented as more eco-friendly than traditional plastics. However, certain environmental concerns—such as the need for specific conditions to biodegrade—may contribute to microplastic pollution. Understanding the degradation of biodegradable plastics is essential for developing effective waste management strategies and mitigating their environmental impacts. This review aims to provide a comprehensive overview of the degradation and toxicity mechanisms of biodegradable plastics, while identifying and emphasizing their potential fates and threats in marine environments. It is also important to acknowledge that the extent of biodegradation and the efficiency of biodegradable plastics in reducing environmental pollution are strongly influenced by factors such as microbial activity, oxygen, temperature, humidity, ultraviolet radiation, pH, and the physicochemical properties of the plastics. This review highlights the research gap in fully understanding the degradation mechanisms and fate of biodegradable nano- and even pico-plastics, which is crucial for developing effective solutions to manage plastic waste in estuarine ecosystems.