Biodegradable vs Compostable Materials and Sustainability
by Heather Smith on Jan 19, 2022
The topic of packaging materials is much less sexy than the look of packaging materials. This article focuses on biodegradable materials and we work to explain biodegradable vs compostable when it comes to the world of skincare containers.
When it comes to cosmetics, skincare, and beauty - beautiful packaging reigns supreme. Unfortunately, greenwashing is very common and much of the marketing hype is focused on esthetics (does it look luxurious and beautiful??) over the environmental impact. This is a shame, because it's possible to have both gorgeous packaging and an improved eco-impact, it just costs the brand a lot more money to produce.
This article builds on our introduction to bio-plastics, and focuses on the differences and meaning of biodegradable vs compostable materials in the cosmetics world.
Biodegradable vs Compostable: TL/DR
We find this whole topic is overwhelming, confusing, and nearly impossible to keep up with. Here's the bottom line:
- The beauty industry has a toxic relationship with plastic that needs to end. Beauty industry pollution makes up an incredible volume of wasted plastic, including liquid microplastics.
- Don't get caught up trying to memorize all the different materials and their pros and cons. As hybrid and composite materials become more effective, it won't be possible to keep up. Some materials go through phases being both praised and vilified. It's the end product and how it degrades that matters most.
- Products labelled as biodegradable or compostable with no easy to find details are extremely suspicious for greenwashing.
- Products labelled as compostable, at the very minimum, must be described as for the industrial or home environment. If they don't tell you the process/certifications, they may be greenwashing.
- The more information the better! It should be easy for consumers to find and very clear. This is one example of a company doing it right:
- Regarding their product, Tishwish clearly states that it is compostable (industrially) or compostable (home) - with a breakdown timeline of 6 months if composted at home. They also clearly advertise their certifications in the European Union.
As exciting, newer materials get developed and more technology gets perfected, the world of biodegradable vs compostable replacements for traditional plastics gets more and more complex.
It's very hard to keep up and to know what's new, true and exciting and what's greenwashing.
If you want to get deeper into the details, keep reading:
What Does Biodegradable Mean?
Biodegradability means that a substance is able to decompose with the help of microorganisms. The process occurs over time and the eventual result is that the entire substance is consumed by bacteria, fungi, or algae.
The fact that something is biodegradable says nothing about the timeline on which that occurs or whether or not the by-products are completely safe for the environment (i.e. methane production from biodegrading substances in landfills is harmful).
Non-plastic natural materials like paper, cardboard, cork or, a bamboo toothbrush will biodegrade over a reasonable timeframe depending on temperature and levels of moisture and oxygen. However, remember that 'reasonable timeframe' in the natural environment isn't defined.
What Does Compostable Mean?
Compostable describes a substance that can biodegrade into natural elements in a compost environment. The process usually takes about 60-180 days.
The ASTM (American Society for Testing and Materials) defines compostable as anything that undergoes degradation by biological processes to yield CO2, water, inorganic compounds, and biomass at a rate consistent with other compostable materials and leaves no visible, distinguishable, or toxic residue.
When consumers see the words "biodegradable" on a packaging label, it can create false reassurance. Throwing these substances in the trash and allowing them to get to the landfill might result in eventual biodegradation; what often isn't clearly communicated is the timeline.
Depending on the chemical structure and origin of the material as well as mechanical properties like thickness, the timeline to full biodegradation may be unacceptably long.
Additionally, remember that a landfill can act like a tomb due to the suffocating lack of oxygen.
If the right conditions don't exist, it will just sit there forever. Biodegradable or not.
Industrial vs Home Composting
Within the category of compostable materials, there is yet another distinction: that of industrial versus home compostability.
Simply explained, the conditions needed to compost some materials in a timely fashion can only be created in a specific, controlled environment.
Industrial composting occurs when various factors are managed in a controlled fashion: temperature (typically 40–60°C/104-140oF), moisture and oxygen content, particle size, the carbon-to-nitrogen ratio, and the amount of turning.
The products of industrial composting are carbon dioxide, water, and compost. The compost is organic matter that includes nutrients, and can be returned to the agricultural environment as a beneficial soil enhancer, if they have not been contaminated by undesired substances.
Currently, rigid skincare containers that are advertised as compostable are generally only able to undergo the process in industrial conditions. Many of these are PLA, which we discuss below. However, newer materials that biodegrade much more readily in the natural environment (when industrial composting isn't available) are hopefully going to become more available.
- Unfortunately, even in the industrial composting world, there is variability in both capacity and capabilities. Some programs are unable to accommodate certain materials even if they are stated to be compostable. It's not uncommon for a community composting program to remove certain items from the stream and send them to the landfill.
- Depending on how advanced your biowaste management program and community infrastructure is, the end compost may be too contaminated by plastics, inks, dyes, etc., to incorporate it back into the agricultural environment.
This might make it all sound too difficult or even hopeless, but don't despair! With community pressure and education, consumer demand, government legislation, and infrastructure development, all of this will become more mainstream and more successful over time.
Global cultural change is not rapid.
What is OXO-Degradable Plastic?
It's important to understand the degradation process and how it differs from biodegradation.
When conventional plastics disappear, it's because the degraded into smaller and smaller particles, until invisible. The chemical structure remains environmentally persistent (usually petroleum based) and is left to start re-accumulating as it integrates into the food chain.
OXO-degradable plastic has biodegradable material mixed with non-biodegradable traditional plastic. With oxygen and sunlight, the container rapidly degrades into little pieces. The problem is that this accelerated breakdown creates microplastics rapidly (degradation, not biodegradation). The microplastics are then left to breakdown as they normally do (which means they don't).
Just because you can't see them, doesn't mean they're gone.
Second generation materials (labelled as oxo-biodegradable) are better. The materials used are all biodegradable, they just do so at different paces. Think of this like hybrid material that can be fully biodegraded with no microplastics, but different materials are blended together in order to make the overall timeline of more acceptable. Some biodegradation is rapid, some is slower; but at the end you're left with nothing and no microplastics.
PLA vs PHA
Another example that illustrates the differences between biodegradability and compostability can be found when comparing PLA to PHA.
PLA (poly lactic acid) initially took the bio-plastic world by storm. Both bio-based and biodegradable, PLA is made from corn, sugarcane, potatoes, and other sources.
PHA (polyhydroxyalkanoate) is the exciting up-and-comer. Also bio-based and biodegradable, PHA is made from corn and other sources.
Both PLA and PHA can be used as substitutes for various traditional plastics (i.e. polypropylene).
A challenge with PLA is that, though biodegradable, it will still take ~100+ years to fully disappear. For rigid items like skincare containers, industrial composting is necessary and it carries with it the risk of contaminating the plastic recycling chain if disposed of incorrectly.
If PLA is mass-produced with incomplete or misleading disposal instructions, we are just going to end up with a huge PLA buildup in our landfills. This is not clearly an improvement, though still likely slightly better on a mass-scale due to the fact manufacturing carbon footprint is lower and resources used are renewable.
PHA, on the other hand, can be structurally modified depending on the product that it is used for. This allows a bit more "designability" when taking end-of-life disposal into account. It still isn't recyclable through normal streams, but it is definitely industrially compostable and some versions are able to be composted in the home compost environment. Biodegradation in the open environment appears to be much faster than PLA, but PHA use is still quite limited to know certainties.
The European Union is way ahead of North America when it comes to eco-friendly packaging materials and skincare containers. It is very likely that future solutions will be hybrid materials that build upon most or all the technologies to date.
Distinguishing compostable vs biodegradable is difficult and that is why it's easy for brands to greenwash. The world of novel materials, especially hybrid materials, is growing too rapidly for everyone to keep up.
Additionally, the lack of urban waste-management and commercial composting infrastructure makes a lot of the new materials useless from an environmental standpoint.
Until we all unite globally to make this a priority, it will be very hard to see any meaningful change in the reduction of plastic waste.
GreenPeace: biodegradable plastics facts
National Geographic article on bioplastics
Plastics Europe Factsheet