A systematic review of published scientific literature conducted
by HYDRA Marine Sciences finds that in the presence of water or
humidity, the bioplastic polylactic acid (PLA) will fully
hydrolyze, and no persistent nano- or microplastics will remain or
accumulate in the environment.
A new meta-study report commissioned by Holland Bioplastics, an
association advancing bioplastics knowledge worldwide, concludes
that the fundamental characteristics of polylactic acid (PLA), a
biobased polymer made entirely from fermented plant sugars, and the
hydrolysis process indicate that PLA does not produce persistent
microplastics. The literature research, completed by HYDRA Marine
Sciences, a research laboratory, shows that unlike
non-biodegradable polymers, which will persist and permanently
accumulate as nano- or microplastics in the environment, PLA will
hydrolyze into molecules of ever-smaller size, becoming soluble in
water and eventually fully biodegraded.
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Mechanisms for PLA Degradation: In the
presence of water (1), PLA undergoes hydrolysis (2) as a pure
chemical process of polymer degradation during which low molecular
weight intermediates (3) such as oligomers and lactic acid monomers
are produced. These become soluble and can be biodegraded (4).
Microbes take up these oligomers and monomers as food (5) and use
them to build up biomass (6) and as energy for metabolism.
Ultimately, this leads to mineralization (7) of the original
polymer carbon into carbon dioxide, methane, and water. (Graphic:
Business Wire)
The report’s findings were drawn from an initial scan of over
30,000 reports, of which 500 were identified by HYDRA as relevant
and of sufficient quality for deeper review. The 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.
Neat PLA and its oligomers are also widely recognized as
non-toxic substances. Lactic acid, the monomer building block of
PLA, is classified as Generally Recognized as Safe by the US Food
and Drug Administration and European Union (EU). Many PLA grades
comply with long-standing global legislation for food contact
requirements in the US and EU. Additionally, specific grades of PLA
have been approved and used for decades in medical applications
such as sutures, tissue scaffolds, and drug administration
substrates. After use in the body, these PLA polymers are safely
absorbed and bioassimilated by the human body.
“As a society, we must work to end the plastics crisis from both
ends: developing collection and waste processing infrastructure and
products that are compostable, reusable, and recyclable while
simultaneously choosing more responsible materials for the products
we rely on today,” said Erwin Vink, Board Member from Holland
Bioplastics. “These findings confirm that as we are growing access
to waste infrastructure globally if PLA is leaked into the
environment, it will not have the long-term impact as a
microplastic that we know occurs with non-biodegradable
polymers.”
“The meta-study shows that in contrast to non-biodegradable
plastic, which will persist and permanently accumulate as micro-
and nanoplastics in the environment, PLA in the environment will
not leave persistent pollution as long as humidity and water are
present,” said Christian Lott, Managing Director, HYDRA Marine
Sciences. “However, we must be aware that it does not belong in the
environment, and it is critical that we do not use these attributes
to encourage littering or slow the development of global waste
infrastructure. Degradation of any material must be balanced with
accumulation, or how much material is entering the environment, in
order to reduce harm to the environment.”
Producing the biobased polymer, PLA, starts with plants as they
sequester atmospheric carbon dioxide in sugar molecules through the
process of photosynthesis. Plant sugars are then fermented using
microorganisms to produce the monomer lactic acid, a safe,
non-toxic substance that is also used to preserve foods and is
produced by our bodies during physical exertion. This lactic acid
is then polymerized into the polylactide (PLA) biopolymer used to
make a wide range of products like cups, cutlery, bin liners, or
flexible food packaging. Because PLA is made from plants that
absorb carbon dioxide (CO2) and water found in nature, when it is
composted, hydrolyzed, or biodegraded, the CO2 and water will
return back to nature, making the process circular.
To follow Holland Bioplastics and its member companies that
supported this study, Futerro, Total-Energies Corbion, and
NatureWorks, as they continue to make strides toward the global
expansion of bioplastics for a circular economy, visit
hollandbioplastics.nl.
About Holland Bioplastics
Holland Bioplastics is an organization that connects parties
directly or indirectly involved in the production of raw materials,
materials and products, and research and marketing for bioplastics
with the aim to spread, share, and make knowledge accessible about
bioplastics. With the vision that bioplastics make an important
contribution to the transition from a linear oil-based economy to a
biobased and circular economy.
About HYDRA Marine Sciences
HYDRA Marine Sciences GmbH is a distinguished institute for
aquatic research, documentation, and consulting. Since 2009, HYDRA
has been involved in the development and application of standard
tests under marine and freshwater field, tank and laboratory
conditions for partners from academia, associations, public
administration, and industry. HYDRA was the first laboratory
recognized for testing biodegradable plastics under the DIN CERTCO
Certifications ‘Biodegradable in Marine Environment’ and
‘Biodegradable in Marine Environment plus’.
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Rozlyn Paradis rparadis@launchsquad.com