Science - December 1, 2011

What we don't know about bioplastics

The environmental impact of plastic is still increasing, as can be seen from the contents of seabirds' stomachs, among other things. Bioplastics are generally seen as the perfect solution, but is that really true? Six fallacies about bioplastics.

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The plastic problem is getting smaller.
Wrong. Pollution by industrial plastic has gone down since the nineteen eighties, says researcher Jan Andries van Franeker of IMARES, but consumer waste has only gone up. Some of this waste ends up in the oceans where, together with the waste dumped by ships, it forms a plastic soup that is causing more and more problems for sea life and birds (see box).
Bioplastics are biodegradable in seawater and are therefore better for the environment.
Wrong. There are bioplastics made from vegetable matter (maize or grass, for example) which are no more biodegradable than any other plastics, says Christiaan Bolck of Food & Biobased Research. Other bioplastics are biodegradable, but at a tempo that varies a lot with the conditions. These plastics are converted into CO2, water and minerals by micro-organisms that need heat and moisture such as a compost heap provides. Conditions in the sea are less favourable, so it takes them longer to break down there.
Ady Jager works at Nature Works, a producer of bioplastics made from plant-based biopolymers. ‘We have had a few phone calls from sea freight companies', she says. ‘They wanted our material so they could throw the plastic overboard. But our biopolymers do not dissolve completely in water. This is a good illustration of the inadequate communication about bioplastics. It is hard enough for us to follow, let alone for the consumer.'

All bioplastics are made from biomass.
Wrong. Some bioplastics are made from oil. These are called bioplastics because they are biodegradable. And that completes the confusion: plastics made from oil can be biodegradable whereas some plant-based bioplastics are not. So the term bioplastics can refer either to the raw material (biomass) or, in the case of oil-based plastic, to its biodegradability.
The term bioplastics is pretty meaningless actually.

All the plastics in the green boxes are categorized as bioplastics.

My plastic carrier bag is oxo-degradable. Biodegradable, in other words.
Wrong. Oxo-degradables look like plastic, but they are not. It is true that the material falls apart, but that is because it contains metal salts which cause it to disintegrate rapidly into tiny particles. Then you cannot see it anymore, but it is still there, in the ocean too. Just as with conventional plastics, these oxo-degradables release harmful substances when they are broken down. So they are not such a great solution after all.

Plastics made from biomass are not better for the environment than ‘ordinary' plastic.

Wrong. After all the misconceptions listed above, you might indeed get the idea that it makes no difference whether plastic is made from oil or from biomass. But the environmental impact depends on more than just the biodegradability. A crucial advantage of plastics made from biomass is that they do not release any toxins when they are broken down. They also score better on CO2 emissions, and they are not dependent on shrinking oil stocks. The environmental impact of biomass plastics is still small, however. Of the 250 million tons of plastic produced worldwide, plant-based bioplastics account for only 0.25 percent.

Bioplastics are the solution to the plastic problem.
Wrong. ‘Our bioplastics are not a solution to ocean pollution', says Jager of Nature Works. To address that problem, she thinks recycling is the best solution. ‘Our plastics are now still burned after use, because volumes are still small, but for larger quantities recycling is perfectly feasible.' Van Franeker favours recycling too, preferably stimulated through a refundable deposit system. He thinks governments should enforce recycling, multiple use and the use of non-polluting materials in the packaging industry. He also thinks the system for collecting shipping waste in port could be vastly improved.

In a fulmar's stomach
Jan Andries van Franeker is doing research on the northern fulmars of the North Sea. He has established that the stomachs of 95 percent of the more than 1,000 fulmars he has studied contain plastic - an average of 30 pieces, weighing 0.33 grams. The equivalent for a human being would be a bowlful of plastic. The birds do not usually die immediately, although damage to their stomachs, constipation and the release of toxins do reduce their chances of survival and of successful reproduction. In most cases, the plastics are ground up in the birds' stomachs and these microplastics are then excreted. Van Franeker estimates that the fulmars process and excrete into the North Sea 6 tons of plastic per year. This creates a plastic soup which, through the workings of the ecosystem, ends up on our plates.
The ecological objectives for waste in the North Sea expressed in the OSPAR convention set an upper limit at 10 percent of the northern fulmars carrying more than the critical amount of 0.1 grams of plastic in their stomachs. Franeker's research shows that 58 percent of the birds are over this limit.
Want to know more about the plastic soup? Follow the three-day campaign on the Plastic Soup (http://plasticsoupfoundation.org/driedaagse/) from 30 November to 2 December, with speakers including Charles Moore (who discovered the plastic soup) and Jan Andries van Franeker.

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