Study Reveals “Compostable” Plastic’s Troubling Longevity in the Ocean

by Klaus Müller
4 comments
compostable plastics

A recent study has shed light on the surprising and concerning findings regarding compostable plastics, specifically PLA, which remain unchanged in marine environments for over a year. Contrary to popular belief, the term “compostable” does not necessarily equate to natural biodegradability. This research highlights the urgent need for standardized tests to verify the true biodegradability of materials promoted as compostable in nature.

The use of the term “biodegradable” for plastic substitutes can be misleading, especially when these materials require high temperatures or industrial composting conditions to break down effectively.

Researchers, led by Dr. Sarah-Jeanne Royer and her team from the Scripps Institution of Oceanography at the University of California, San Diego, conducted the study. They examined the behavior of PLA, a commonly used compostable plastic derived from the fermentation of sugars and starches, in a natural marine environment. The goal was to understand if PLA and other plastic substitutes genuinely biodegrade when exposed to real-world conditions.

During the study, samples of PLA, oil-based materials, cellulose-based materials, and a blend of cellulose-based and oil-based materials were submerged in cages in coastal waters off La Jolla, California. Weekly examinations were performed to assess disintegration, and the samples were returned to the ocean after a few hours.

Surprisingly, the cellulose-based material showed rapid degradation in less than a month, primarily through biological processes that produced CO2. In contrast, neither the oil-based plastic nor the blend of materials, including PLA, showed any signs of degradation throughout the 14-month experiment.

Dr. Royer pointed out that referring to compostable plastics as biodegradable is misleading, as PLA-based plastics need to be composted in controlled facilities to achieve their compostable potential as substitutes for oil-based plastics.

The researchers emphasized the necessity of standardizing tests to verify the biodegradability claims of materials marketed as compostable or biodegradable, like PLA, under natural environmental conditions. Consumers concerned about microfiber plastic pollution should be informed and mindful of the materials they purchase.

The accumulation of oil-based plastic waste in the ocean poses a significant ecological problem for marine life. Macroscopic plastic items, such as water bottles, can persist in their original form for decades, and even when they break down into microplastics, they remain undegraded and pollute the oceans.

This study represents pioneering research in comparing the biodegradability of different material types (natural to fully synthetic and bio-based materials) in natural environmental conditions and controlled closed systems. It underscores the urgency of finding reliable solutions to combat plastic pollution in marine ecosystems.

The work is being supported by the Deheyn lab BEST Initiative (Biomimicry for Emerging Science and Technology Initiative), which facilitates academia-industry collaboration for nature-inspired research. The funders do not influence data collection, analysis, or publication decisions but may be involved in discussing study design and interpreting data outcomes to some extent.

In conclusion, the study’s outcomes raise concerns about the true biodegradability of compostable plastics in marine environments, emphasizing the need for stricter testing and consumer awareness regarding environmentally friendly materials.

Reference: “Not so biodegradable: Polylactic acid and cellulose/plastic blend textiles lack fast biodegradation in marine waters” by Sarah-Jeanne Royer, Francesco Greco, Michaela Kogler and Dimitri D. Deheyn, 24 May 2023, PLOS ONE.
DOI: 10.1371/journal.pone.0284681

Frequently Asked Questions (FAQs) about compostable plastics

Q: What did the study reveal about compostable plastics like PLA in the ocean?

A: The study revealed that compostable plastics, specifically PLA, remain unchanged in the ocean for over a year, indicating that being labeled as “compostable” doesn’t necessarily mean they are naturally biodegradable in marine environments.

Q: Why is the term “biodegradable” deceptive when applied to some plastic substitutes?

A: The term “biodegradable” can be misleading because some plastic substitutes, including PLA, require specific conditions like high temperatures or industrial composting facilities to break down effectively. In natural environments, these materials may not biodegrade as expected.

Q: What were the key findings of the research conducted on PLA and other materials?

A: The study found that cellulose-based materials biodegraded quickly in less than a month, while oil-based plastics, a blend of materials, and PLA did not show signs of degradation throughout the 14-month experiment in a marine environment.

Q: What is the impact of oil-based plastic waste on marine life?

A: Oil-based plastic waste accumulation in the ocean is a significant ecological problem for marine life. Macroscopic plastic items can persist for decades, and even when they break down into microplastics, they remain undegraded and pollute the oceans.

Q: What is the recommended approach for compostable plastics like PLA to achieve their compostable potential?

A: Compostable plastics like PLA should be composted in controlled facilities to achieve their potential as compostable substitutes for oil-based plastics. Composting in industrial contexts is necessary to ensure proper degradation.

Q: Why is it essential to standardize tests for materials marketed as compostable or biodegradable?

A: Standardizing tests is crucial to verify the true biodegradability of materials like PLA under natural environmental conditions. It helps ensure that consumers can trust the claims made about the compostability or biodegradability of products and make informed choices about their environmental impact.

Q: What role do funders play in the research?

A: The funders support the research through initiatives and grants, but they do not influence data collection, analysis, or publication decisions. They may be involved in discussing study design and interpreting data outcomes to some extent but have no role in directing the publication’s content, presentation, or conclusion.

Q: How can consumers help combat plastic pollution in marine ecosystems?

A: Consumers can contribute by being informed and mindful of the materials they purchase. Opting for sustainable alternatives and supporting environmentally friendly practices can help reduce plastic pollution in marine environments.

More about compostable plastics

  • PLOS ONE: “Not so biodegradable: Polylactic acid and cellulose/plastic blend textiles lack fast biodegradation in marine waters”
    Link

  • Scripps Institution of Oceanography at the University of California, San Diego
    Link

  • Biomimicry for Emerging Science and Technology Initiative (BEST Initiative)
    Link

  • Young Thousand Talents Plan of China
    Link

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4 comments

GreenThumb78 July 21, 2023 - 1:18 pm

whoa, didn’t know compostable plastics could stick around for so long! we gotta spread the word about this and put pressure on companies to use better alternatives. we can’t keep harming our oceans like this! #plasticpollution #saveouroceans

Reply
JohnDoe91 July 21, 2023 - 7:37 pm

wow this study found compostable plastics don’t break down in the ocean! that’s a big problem! they should really tell us these things when they sell us the stuff, ya know? like, we gotta know if it’s gonna harm the environment or not. and those microplastics, they’re everywhere, not good at all!

Reply
EcoWarrior23 July 22, 2023 - 3:39 am

this research is so important, we can’t just assume something is “biodegradable” if it doesn’t break down in nature. we need to be more careful with our choices and push for better testing and regulation. plastic pollution is killing marine life, we gotta do better!

Reply
OceanWatcher55 July 22, 2023 - 8:12 am

this is why we need better regulations and consumer education. people think they’re doing good by using compostable plastics, but turns out they might not be as eco-friendly as advertised. we must demand transparency and more responsible choices!

Reply

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