A new comprehensive study commissioned by Holland Bioplastics and conducted by HYDRA Marine Sciences has confirmed that bioplastic polylactic acid (PLA) fully breaks down in the presence of water or humidity, leaving no lasting microplastics in the environment. This research, which analyzed over 30,000 reports and reviewed 500 in detail, underscores PLA's ability to hydrolyze and biodegrade completely.
The study emphasizes that PLA, a polymer made from fermented plant sugars, predominantly degrades through hydrolysis. This process, driven by moisture, gradually reduces the molecular weight of PLA objects, fragmenting them into oligomers and lactic acid monomers. These smaller molecules are then biodegraded by microorganisms into biomass, water, and carbon dioxide.
The report addresses critical aspects of PLA's behavior in the environment:
Rate and Extent of Degradation: The disintegration of PLA in soil, freshwater, and marine environments varies, with complete mineralization potentially taking months to decades, depending on temperature and exposure conditions.
Microplastic Formation: While PLA microplastics have been rarely found in the environment, the increasing use of PLA suggests that such occurrences might become more frequent. However, these microplastics eventually break down completely.
Microbial Interaction: Specific microbes, including 78 bacteria, 27 fungi, and 2 archaea, have been identified to hydrolyze PLA in controlled settings. Direct enzymatic degradation by these microbes in natural environments remains largely unproven, likely due to insufficient detection methods.
The impact of PLA on ecosystems is multifaceted:
Biodegradation Pathways: PLA's breakdown into micro- and nanoparticles is part of a natural transition phase before complete mineralization. Unlike non-biodegradable plastics, PLA particles eventually dissolve and are assimilated into the environment, albeit over varying timeframes.
Ecotoxicity: Studies indicate that neat PLA generally poses minimal harm to algae, plants, and animals. However, commercial products made with PLA, often mixed with other polymers and additives, complicate the assessment of its true environmental impact.
Chemical Degradation: Over time, the hydrolysis of PLA can alter water pH levels, potentially affecting sensitive organisms, especially in confined environments. Yet, in open systems, these changes are expected to be negligible due to dilution effects.
On the regulatory front, the European Union's Action Plan, "Towards Zero Pollution of Air, Water and Soil," and Regulation 2019/1009, which mandates biodegradability for certain applications, highlight the need for clear and actionable policies for biodegradable materials like PLA. Current testing and certification frameworks often fail to account for PLA’s unique degradation profile, treating it as non-biodegradable under standard conditions.
The report calls for comprehensive, long-term studies to better understand the degradation rates of PLA under typical environmental conditions. Additionally, it emphasizes the need for:
Innovative Testing Methods: Development of new testing protocols that accommodate varying environmental conditions and longer timeframes to reflect real-world biodegradation.
Detailed Impact Assessments: Evaluating the potential transfer and impact of biodegradable plastics across different environmental settings, such as soil to freshwater.
Legislative Action: Prompt and carefully considered policy measures to manage and mitigate the environmental footprint of PLA and other biodegradable plastics, accounting for variabilities from legacy plastics.
As PLA continues to gain traction as a sustainable alternative in the plastics industry, it is crucial to balance its environmental benefits against potential risks. Ensuring that PLA and similar materials are thoroughly understood and properly managed will be key to achieving the goals of broader global sustainability objectives.
