On June 25, a new comprehensive study commissioned by Holland Bioplastics concluded that the basic properties and hydrolysis of polylactic acid (PLA), a biobased polymer made exclusively from fermented plant sugars, indicate that PLA does not produce persistent microplastics.
Literature studies conducted by research laboratory HYDRA Marine Sciences have shown that non-biodegradable polymers persist in the environment in the form of nano- or micro-plastics and accumulate permanently, while polylactic acid (PLA) hydrolyzes into smaller and smaller molecules that dissolve in water and eventually biodegrade completely.
This conclusion came from an initial review of more than 30,000 scientific reports, 500 of which were identified by HYDRA as relevant and of sufficiently outstanding quality to warrant an in-depth review. Research has confirmed that environmental degradation of PLA is primarily driven by hydrolysis, an abiotic process that occurs in the presence of moisture or humidity. As long as these conditions exist, the molecular weight and size of any PLA object or fragment will continue to decrease through hydrolysis at a rate determined by temperature until the polymer chains become so short that the material is soluble in water. These soluble materials, oligomers and lactic acid monomers will then be biodegraded by microorganisms into biomass, water and carbon dioxide.
PLA Degradation Mechanism: In the presence of water (1), PLA undergoes hydrolysis (2), a purely chemical polymer degradation process in which low molecular weight intermediates (3) such as oligomers and lactic acid monomers are produced. These intermediates become soluble and biodegradable (4), and microorganisms use these oligomers and monomers as food (5) and utilize them to form biomass (6) and as metabolic energy. Ultimately, this leads to carbon mineralization of the original polymer (7) into carbon dioxide, methane and water.
Pure PLA and its oligomers have long been widely recognized as non-toxic substances. PLA's monomeric lactic acid is classified as a recognized safe substance by the U.S. Food and Drug Administration and the European Union. Many PLA grades comply with long-standing U.S. and EU legislation on global food contact requirements. In addition, specific grades of PLA have been approved and used for decades in medical applications such as sutures, tissue scaffolds and drug delivery substrates. Upon entry into the body, these PLA polymers are safely absorbed and bioassimilated by the body.
“As a society, we must work to end the plastics crisis on two fronts: by developing compostable, reusable and recyclable products and by developing the infrastructure to collect and dispose of the waste, while choosing more responsible materials for the products we rely on in our daily lives,” said Dutch Bioplastics Consortium board member Erwin Vink said, “These studies confirm that even if PLA leaks into the environment, it will not have the same long-term environmental impacts as microplastics that occur in non-biodegradable polymers as we know them.”
“This comprehensive study shows that unlike non-biodegradable plastics, which persist and accumulate permanently in the environment in the form of microplastics and nanoplastics, PLA does not leave a lasting legacy of contamination as long as there is moisture and water in the environment,” said Christian Lott, Head of Marine Science at HYDRA. “Of course, we must also realize that it does not belong in the environment. We cannot use these properties to encourage littering or to slow down the development of a global waste infrastructure. The degradation of any material must be balanced with the amount of material that accumulates or enters the environment to minimize harm to the environment.”
The bio-based polymer PLA begins in plants, which sequester atmospheric carbon dioxide in sugar molecules through photosynthesis, and then use microorganisms to ferment the plant sugars to produce monomeric lactic acid, a safe, non-toxic substance also used to preserve food, and which the human body produces during physical activity. Lactic acid polymerizes into polylactic acid (PLA) biopolymers, which can be used to make a variety of products such as cups, cutlery, garbage bags or flexible food packaging. Since PLA is made from plants that absorb carbon dioxide (CO2) and water from nature, when it is composted, hydrolyzed or biodegraded, the CO2 and water are returned to nature, thus enabling a circular model for the entire process.
The Holland Bioplastics Consortium (Holland Bioplastics) is an organization that connects all parties directly or indirectly involved in the production of raw materials, materials and products as well as in the research, development and marketing of bioplastics, with the aim of disseminating, sharing and popularizing knowledge about bioplastics. Its vision is to actively promote the important contribution of bioplastics in humanity's transition from a linear petroleum-based economy to a biobased and circular economy.
HYDRA Marine Science is a renowned organization for aquatic research, documentation and consulting. Since 2009, HYDRA has been involved in the development and application of standardized tests in marine and freshwater field, tank and laboratory conditions for partners in academia, associations, public administrations and industry HYDRA was the first laboratory to be DIN CERTCO accredited for the testing of biodegradable plastics in the “biodegradable in the marine environment” and “biodegradable+ in the marine environment”. “Biodegradable in the marine environment +” for biodegradable plastics.
