Biodegradable packaging can help tackle toxic plastic pollution. But what does it really mean when a product is labelled as biodegradable? We explain the term and how it differs from ‘compostability’.
The problem
Plastic pollution is choking the planet. 99% of all plastics today are made from petrochemicals that stay in the environment for hundreds of years, breaking down into hazardous microscopic pieces. These particles become small enough to leak into the human food system via soil, plants, and livestock.
All life on earth has become unwilling guinea pigs in the microplastics experiment: scientists are not clear on how damaging the long-term health effects of exposure will be. Urgent solutions are needed and biodegradable materials offer one way out. Eliminating plastics outright where possible should be the priority. However, certain single-use products need plastic or plastic-like packaging for hygiene purposes. Plastics are also hard to replace in many industrial applications.
What industry needs are materials that mimic oil-based plastics but behave like biological materials at the end of their product life. This is where biodegradable plastics come in.
The ideal sustainable packaging
By 2040, packaging is forecast to account for roughly 40 percent of plastic waste generation worldwide, according to one estimate.
Single use plastic packaging where that serves some kind of hygiene purpose can be difficult to eliminate. This is an obvious area where biodegradable alternatives could be useful.
The ideal sustainable packaging material for single use would decompose if left in the natural environment, just like a piece of wood on a forest floor.
An ideal sustainable packaging material would also decompose without toxic byproducts and only release harmless substances found everywhere in nature.
There is one caveat here, which is that no material – even completely natural ones – is entirely ‘traceless’. This is obvious in the sense that matter never really disappears.
In a less obvious sense, no material is universally biodegradable in every environment on earth. This is because the temperature, light, and the microbe species present in any particular ecosystem will determine how fast any material will degrade and whether they do so safely. Every ecosystem is different so there is no guaranteeing that a material will behave the same way in all of them.
That being said, unprocessed natural materials (think bark, fur, food waste) and certain processed ones (plastics made from plant matter) tend to break down more safely, quickly, and in far more diverse environments, than materials made using petrochemicals.
Taking these constraints into account, a truly sustainable packaging material would be one that breaks down into harmless compounds over a reasonable time span in many different natural environments, especially those where plastic waste tends to build up: soil and the sea.
This ideal sustainable packaging will most likely be a biomaterial or bioplastic, since they tend to be easier to break down into environmentally harmless compounds.
Bioplastics are a specific type of biomaterial. Many are suitable for packaging because they can closely resemble oil-based plastics.
The diversity of bioplastics we have at our disposal today is matched by the diversity of behaviours they exhibit once discarded. Which ones biodegrade? And what does that mean?
What biodegradable really means
Today, we can fashion many kinds of plastics using a range of raw biological materials. To sort through the choice on offer, eco-aware consumers seeking sustainable packaging will often look out for keywords like ‘biodegradable’. However, this marketing term does not necessarily mean that the product is better for the planet.
In general use, a biodegradable material is one that breaks down under certain conditions. However, it says nothing about precisely what conditions the material needs to break down safely, nor the amount of time that it will take to break down.
When you see the term ‘biodegradable’ on a product in the supermarket, it tends to mean something a bit more specific: that the material breaks down only if collected and treated in a specialised composting plant. These facilities offer a finely-tuned environment designed to break apart the bonds of these materials.
Unable to break down safely in marine or soil environments, materials labelled biodegradable need to be taken to a properly equipped industrial composting facility in order for them to meaningfully chip away at the problem of plastic pollution.
Biobased and biodegradable plastics like PLA and PP do not break down safely or quickly in a natural environment or even a home compost heap. The need for industrial facilities is not widely known among consumers, many of whom try (and fail) to compost these materials in their garden.
What we are seeing here is consumers mistake biodegradable products for home-compostable ones. The latter, which include potato starch bioplastics and certain algal bioplastics, can easily break down in a garden compost heap.
The problem with ‘biodegradable’ materials
The problem with biodegradable materials does not end at a lack of consumer awareness around their end-of-life treatment procedures. There is also a global infrastructural bottleneck.
Biodegradable plastics confront the same problem as recyclable plastics since there is nowhere near enough industrial capacity to break down the amount that is manufactured each year.
In theory, both biodegradable bioplastics and plastic recycling are strong solutions to the plastic pollution problem. Yet in practice, margins have remained too low for recyclers and composting firms alike to invest in enough capacity.
Without the capacity to treat them, a lot of biodegradable bioplastics are dumped into the environment, where these biobased materials can be just as dangerous to human health and wildlife as ordinary synthetic plastics.
More infrastructure for collecting and composting biodegradable plastics is needed to prevent them from contaminating natural environments. This is especially because we cannot use compostable materials in every applications.
There is often a trade-off between long-lasting material performance and compostability. Home-compostable materials are ideal substitutes for single use petroleum plastics packaging. However, they are less suitable for replacing other more durable applications such as industrial equipment or automotives.
As biodegradable plastics often have properties that are not easy to achieve with materials that break down so readily, they will remain an important part of the sustainable materials toolkit.
Standards and regulations
For the ‘biodegradable’ label to better support sustainable consumption, however, we need more laws governing when and how companies can use the term on their product.
This includes the UK, where companies are not regulated in their use of biodegradability claims, leaving the door open to greenwashing and consumer mistrust.
In the EU, there is a harmonised standard that lays out the criteria that a product has to meet to be classed as industrially compostable. There is another standard laying out the definition of biodegradable mulch films used for agriculture. However, there is no general standard defining what it means for a material to be ‘marine biodegradable’.
Standards are one thing but imposing regulations that govern how companies talk about their products is a much more difficult step. There is some movement on this in the EU parliament. In 2024, it finally adopted a directive that would force companies to submit evidence if they are to use marketing claims like “biodegradable”.
The science of biodegradation
Formulating regulations around biodegradability claims can be complicated but not impossible. There are many rigorous standards and assessment frameworks that have been developed by international and national bodies on the question.
Scientists already deploy precise ways of assessing biodegradability. Mostly this revolves around measuring how much of a material degrades in a given time frame in a given environment.
For example, a UCL study into materials labelled ‘home-compostable’ reported that 45% of materials they tested had either completely disintegrated or broken down to less than 2mm.
Robust labeling laws would force companies to label their products in line with the material science of biodegradability, taking the guesswork out of sustainable purchasing. Marketing language would be tied to laboratory, simulation, and field tests that show how rapidly materials break down in synthetic, industrial, and natural environments.
Industry & consumers need clear labels
Biodegradable bioplastics could play a vital role in the fight against plastics pollution. However, regulations are hampering industry growth.
Regulation is an under-appreciated factor in scaling the biobased industries. Today, a biobased company could develop a low-cost, high-performance biopolymer that easily biodegrades in diverse natural environments. Yet without the backing of regulatory authorities, it will have no easy way of proving these claims to the consumer.
Verified labelling would help sustainable materials companies find and expand markets more efficiently.
Consumers equally have a lot to gain from scientifically-grounded and tightly regulated labelling tiers indicating the degradability of packaging. It would leave them much less vulnerable to paying a green premium for products that do not necessarily live up to its sustainability claims.
In the rush for renewable alternatives, consumers and producers must not overlook the nuances of how materials behave when they reach natural environments. Further growth in the biomanufacturing industries will depend on clear labelling regulations that give producers and consumers alike much-needed clarity.
