If plastic is the problem, is bioplastic the solution?

Mariko McTier
Jul 19, 2019 · 5 min read

In June 2019, one of Japan’s largest retailers — convenience store chain Seven Eleven — announced that it will be replacing the packaging of its rice balls (onigiri 🍙) with bioplastic.

🍙 Onigiri 🍙 lined up in Seven Eleven — a convenience store, or ‘conbini’ (Photo: Mariko McTier)

Considering that Japan has the world’s second highest rate of plastic packaging waste per capita in the world (second only to the US) and a study recently found 3 million plastic bags in Osaka bay alone, this is welcome news. But, is bioplastic really the solution?

Despite its name, a bioplastic is not automatically a sustainable solution.

You might expect a bioplastic wrapper to break down on your compost heap, or to at least have a lower carbon footprint, but it might surprise you to find out that neither is necessarily true.

So as Japan (albeit cautiously) explores the viability of more sustainable plastic production and consumption, here are 4 facts about bioplastics to consider.


1 ) First things first…what is a bioplastic?

As you may have started to guess, ‘bioplastic’ is a confusingly vague term that can mean one or both of two things:

So far so good…?

In principal, a bioplastic that is either — or both — of the definitions above should be an improvement on the non-bio-based, non biodegradable plastics that are currently most common. Either because it reduces our use of fossil fuels and CO2 emissions (bio-based), or because it will biodegrade more quickly (biodegradable).

But here are some of the reasons it may not be the panacea we might be led to believe.

2 ) Bio-based and biodegradable are NOT one and the same

Despite being made from organic materials, a bio-based plastic may be neither biodegradable or compostable.

Although Seven Eleven’s new onigiri packaging — called ‘botanical film’ (….???) — is reported to be partly made from sugar cane, it doesn’t appear to be biodegradable or compostable, and is still largely made from petroleum-based resins.

If it washes into our oceans, it’s going to cause trouble for our underwater friends for just as long as conventional plastic.

Not so ‘eco’.

(Though, depending on where you live, it might be possible to add it to your recycling —but that’s a topic for another day).

On the flip side, a biodegradable plastic may still be derived completely from petrochemicals, with additives such as antioxidants added to make it break down more quickly in nature. This might help prevent long-lasting plastic waste on our beaches and in our oceans, but we are still using petrochemicals to produce it.

So to recap, NOT ALL bioplastics are biodegradable, and NOT ALL bioplastics are derived from biomass.

Here’s a helpful diagram from European Bioplastics, lest you be confused…!

3 ) We don’t yet have adequate facilities to compost or recycle these new plastics

Some bio-based plastics are compostable in 1-6 months, but only under very specific conditions (e.g. a constant temperature of 60℃ with a regular top-up of microbes), and this generally requires an industrial composter. Unfortunately in Japan, and in most parts of the world, we don’t have a lot of them, so it is likely to be incinerated (or go to landfill).

And, to complicate things further, some of the bio-based plastics that are technically recyclable (e.g. PLA) are chemically different from conventional plastics, so can’t be recycled in existing facilities. If a piece of PLA does end up in an existing recycling facility, it becomes a pollutant, contaminating and downgrading the quality of the recycled plastic.

Different types of plastics have to be carefully sorted, cleaned and dried before recycling

4 ) Production can compete with food production

If the raw material to produce the bio-based plastic is grown specifically as a feedstock for plastic (i.e. is not waste/an agricultural by-product), it will compete for land with food production, for which there is growing demand (an estimated 70% increase in food production is required by 2050).

Some bioplastics (e.g. PHA) that use microbes to turn waste food (and even human waste!) into plastic are being developed to help address this problem, but for the more prevalent bioplastics made from corn starch / sugar cane, for example, this use of land is unlikely to be sustainable.

Corn starch is commonly used in the production of bioplastic

So, is it better for the planet?

Bioplastics — either by reducing our dependency on fossil fuels and overall CO2 emissions, or by improving the biodegradability of plastics — are, in many cases, an improvement upon existing petrochemical-based, non-biodegradable plastic.

But they are far from perfect.

If you take a look at the life-cycle of a bioplastic, including the context for its production, use, and end-of-life, it’s clear that it requires a great deal more than swapping out conventional packaging for bioplastic to be ‘sustainable’.

What can we do about it?

I’m glad to see companies like Seven Eleven finally recognise that — both for the sake of our planet and the future of their businesses — they need to carefully review their existing, unsustainable business practices. But we also need to remain critical, and ensure that ‘eco branding’ such as their (spuriously named) ‘botanical film’ does not allow for complacency, or detract from the pursuit of a truly sustainable, circular solution.

Seven Eleven’s ‘botancial film’, now used to package its rice balls across Japan (Photo: Mariko McTier)

Crucially, Seven Eleven’s new onigiri packaging should not be treated as a solution in and of itself. It is but a baby step — part of a much larger and more drastic transition that needs to happen. For any significant change to happen, we also need to:

I’m optimistic that both of these are possible, but they have to happen hand-in-hand with the adoption of bioplastics, as only then will we even begin to make a dent in the level of plastic packaging waste being produced in Japan.


Social Innovation Japan

Social Innovation Japan is a platform for social action. We organise events, workshops, and programs for people to learn, connect and take action on today’s most pressing challenges. Together, we are building a movement for social good from Japan, with the rest of the world.

Mariko McTier

Written by

Mariko is Co-Founder of Social Innovation Japan — a platform to provide people with the tools, information, and network to tackle real-world problems.

Social Innovation Japan

Social Innovation Japan is a platform for social action. We organise events, workshops, and programs for people to learn, connect and take action on today’s most pressing challenges. Together, we are building a movement for social good from Japan, with the rest of the world.

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