A few months ago, while conducting a feasibility study for an innovative sustainable product, I picked up a cosmetic product in a store. “100% biodegradable!” jumped out at me from the label. As a Sustainability Detective, my eyebrows immediately went up. Because my first question is always, “How?”

I can’t shake this question. I see claims of biodegradability everywhere in the industry, but I can’t find the details. Under what conditions does it break down? Over what time frame? And what’s the impact on our ecosystems?

When ‘biodegradable’ doesn’t mean what we think

You know, those laundry detergent pods? They’re marketed as “biodegradable,” made from PVA (Polyvinyl Alcohol). Sounds good, right? But here’s the reality: PVA only breaks down under very specific microbial conditions [1] — conditions often unmet in standard wastewater treatment plants, leading to potential accumulation in waterways.[1] Concerns have even been raised about microplastic contamination, with studies detecting plastic particles in human breast milk, although the specific contribution of PVA requires further research.[2] This gap between marketing and reality is not an isolated incident; it is a pattern I see in the cosmetics industry as well.

Disclaimer: The debate around PVA is ongoing. While some studies highlight degradation challenges, the U.S. Environmental Protection Agency (EPA) maintains it doesn't currently meet their criteria for problematic persistent chemicals, whereas the OECD calls PVA a problem chemical. [3]

Testing is a great first step to take!

In the cosmetics industry, biodegradability claims often rely on standardised tests, primarily the OECD 301 series for 'Ready Biodegradability'. Test 301B, for example, measures CO₂ evolution in an aquatic medium over 28 days. A pass requires reaching 60% biodegradation within a '10-day window' after degradation begins.

But here's what simplified marketing claims often omit:

• Variety of Tests: The OECD 301 series includes six different methods (A-F) simulating various conditions (e.g., CO₂ evolution, oxygen consumption, dissolved organic carbon).[4] Beyond this, OECD 302 assesses 'inherent biodegradability' (potential to degrade under favourable conditions), and OECD 303 simulates degradation in activated sludge, relevant for wastewater treatment.[4]

• Readily' vs. 'Inherently' vs. 'Ultimately': 'Readily biodegradable' (passing OECD 301) implies relatively quick and complete degradation in diverse environments. 'Inherently biodegradable' (passing OECD 302 but not 301) suggests degradation is possible but might be slower or require specific conditions. 'Ultimately biodegradable' means complete breakdown occurs, but the timeframe might be longer than 28 days. These nuances are often lost.

When a brand simply states “biodegradable” without specifying which test was used or the results, it tells us very little about how that ingredient will actually behave in our rivers, lakes, and oceans.

From 'Persistent' to 'Non-Persistent': A New Way of Thinking

At that symposium on circularity, I learned a concept that has stuck with me: the difference between 'persistent' and 'non-persistent' materials. Fossil plastic is persistent: it can take 1.000 years or it to decompose.[5] Take a moment to imagine that with the amount of plastic you personally dispose in a year. Multiply by 1.000. Getting claustrophobic?

Certain biobased materials are non-persistent: they disappear within one generation. This way of thinking changes the conversation from “Is it biodegradable?” to “How long does it last in our environment?”

What does this mean for our industry?

As cosmetic professionals, we need to ask ourselves four critical questions for every biodegradability claim:

1. Under what specific conditions does the material break down?

2. How long does this process take in the real world?

3. What happens to the breakdown products in our water systems?

4. Is the material persistent or non-persistent in the environment?

The way forward

Instead of vague claims like “100% biodegradable”, we can now be more specific: “Readily biodegradable (OECD 301B >60% in 28 days)” or “Biodegradable in marine water (OECD 306)”. Not sexy, but fair.

As a Sustainability Detective, I see a clear path forward, though it requires effort:

1. Demand Specificity: Ask suppliers not just _if_ an ingredient is biodegradable, but _how_ (which test, what result, under what conditions).

2. Prioritise 'Readily Biodegradable': Favour ingredients proven to pass stricter OECD 301 tests.

3. Consider Real-World Conditions: Investigate degradation data relevant to the product's likely end-of-life environment (freshwater, marine, soil, wastewater treatment).

4. Be Transparent: Communicate honestly with consumers about the nuances of biodegradability, even if it's complex. Explain the tests used and what the results mean.

Many ingredients still lack comprehensive, publicly available biodegradability data, particularly for real-world conditions. More research and testing, especially under environmentally relevant scenarios, are urgently needed. But above all, our industry needs a commitment to rigorous honesty.

Would you like to participate in this research? I am looking for partners who want to dig with me into the real impact of biodegradability claims. Because only by being fully transparent about the conditions and limitations can we build a truly sustainable industry.

Are you ready to look beyond the buzzwords? Get in touch. I would love to have a virtual cup of coffee with you to discuss the possibilities.

1. Rolsky, Charles, and Varun Kelkar. 2021. ‘Degradation of Polyvinyl Alcohol in US Wastewater Treatment Plants and Subsequent Nationwide Emission Estimate’. _International Journal of Environmental Research and Public Health_ 18 (11): 6027. [https://doi.org/10.3390/ijerph18116027](https://doi.org/10.3390/ijerph18116027).
2. Adjama, Irédon, Hemen Dave, Bachir Yaou Balarabe, Vimbai Masiyambiri, and Manka Marycleopha. 2024. ‘Microplastics in Dairy Products and Human Breast Milk: Contamination Status and Greenness Analysis of Available Analytical Methods’. _Journal of Hazardous Materials Letters_ 5 (November):100120. https://doi.org/10.1016/j.hazl.2024.100120
3. https://www.resources.aropha.com/docs/test-methods/biodegradation-test-method-overview/](https://www.resources.aropha.com/docs/test-methods/biodegradation-test-method-overview/
4. Organisation for Economic Co-operation and Development, _OECD Guidelines for the Testing of Chemicals, Section 3, Degradation and Accumulation_ (Paris: OECD Publishing, continuously updated), https://www.oecd-ilibrary.org/environment/oecd-guidelines-for-the-testing-of-chemicals-section-3-degradation-and-accumulation_2074577x
5. https://www.savemoneycutcarbon.com/learn-save/how-long-does-it-take-for-plastic-to-biodegrade/