Hydrolysis prevents the formation of persistent PLA microplastics in the environment

A new meta-study funded by Holland Bioplastics and completed by HYDRA Marine Sciences finds that in the presence of water or humidity, PLA will fully hydrolyze and no persistent nano- or microplastics will accumulate
By Leah Ford, Global Marketing and Communications Director

Today Holland Bioplastics released an important meta-study that summarizes currently available peer-reviewed research on how polylactic acid (PLA) interacts with the environment. This study, conducted by HYDRA Marine Sciences, found that in the presence of water or humidity, PLA will fully hydrolyze, and no persistent nano- or microplastics will remain or accumulate in the environment. 

HYDRA Marine Sciences is a research institute known for their work in developing standards and conducting tests on the biodegradability of materials under marine and freshwater field, tank and laboratory conditions. To understand the fate of PLA nano- and microplastics in the environment, HYDRA began with an initial scan of over 30,000 reports, of which 500 were identified as relevant and of sufficient quality for deeper review. Their research confirmed that the environmental degradation of PLA is mainly driven by hydrolysis, an abiotic process that occurs in the presence of moisture or humidity. As long as these conditions prevail, the molecular weight and size of any PLA objects or fragments will continually decrease via hydrolysis, at a rate determined by temperature, until the polymer chains are so short that the material becomes soluble in water. These soluble substances, oligomers and lactic acid monomers, will subsequently be biodegraded by microorganisms into biomass, water, and carbon dioxide.

The process of disintegration by hydrolysis followed by biodegradation is the same process that products made from PLA undergo when in a composting environment. This is also why PLA does not create persistent microplastics in compost either.

While it remains our highest priority that we don’t design materials or products that encourage littering, it is important that we understand the impact materials have on the environment in a worst-case scenario. That’s why it’s useful to conduct these types of studies and develop a more nuanced understanding of the materials we’re scaling up to replace persistent, fossil-based plastics.

For a more on this topic:

Executive Brief (PDF)

Technical Summary Report (PDF)

Press Release from Holland Bioplastics