Say Anything Blog

‘Sustainable’ bio-plastic can damage the environment

Corn-based material emits climate change gas in landfill and adds to food crisis

The worldwide effort by supermarkets and industry to replace conventional oil-based plastic with eco-friendly “bioplastics” made from plants is causing environmental problems and consumer confusion, according to a Guardian study.

The substitutes can increase emissions of greenhouse gases on landfill sites, some need high temperatures to decompose and others cannot be recycled in Britain.

Many of the bioplastics are also contributing to the global food crisis by taking over large areas of land previously used to grow crops for human consumption.

The market for bioplastics, which are made from maize, sugarcane, wheat and other crops, is growing by 20-30% a year.

The industry, which uses words such as “sustainable”, “biodegradeable”, “compostable” and “recyclable” to describe its products, says bioplastics make carbon savings of 30-80% compared with conventional oil-based plastics and can extend the shelf-life of food.

Concern centres on corn-based packaging made with polylactic acid (Pla). Made from GM crops, it looks identical to conventional polyethylene terephthalate (Pet) plastic and is produced by US company NatureWorks. The company is jointly owned by Cargill, the world’s second largest biofuel producer, and Teijin, one of the world’s largest plastic manufacturers.

Pla is used by some of the biggest supermarkets and food companies, including Wal-Mart, McDonald’s and Del Monte. It is used by Marks & Spencer to package organic foods, salads, snacks, desserts, and fruit and vegetables.

It is also used to bottle Belu mineral water, which is endorsed by environmentalists because the brand’s owners invest all profits in water projects in poor countries. Wal-Mart has said it plans to use 114m Pla containers over the course of a year.

While Pla is said to offer more disposal options, the Guardian has found that it will barely break down on landfill sites, and can only be composted in the handful of anaerobic digesters which exist in Britain, but which do not take any packaging. In addition, if Pla is sent to UK recycling works in large quantities, it can contaminate the waste stream, reportedly making other recycled plastics unsaleable.

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Concern is mounting because the new generation of biodegradable plastics ends up on landfill sites, where they degrade without oxygen, releasing methane, a greenhouse gas 23 times more powerful than carbon dioxide. This week the US national oceanic and atmospheric administration reported a sharp increase in global methane emissions last year.



“It is just not possible to capture all the methane from landfill sites,” said Michael Warhurt, resources campaigner at Friends of the Earth. “A significant percentage leaks to the atmosphere.”

“Just because it’s biodegradable does not mean it’s good. If it goes to landfill it breaks down to methane. Only a percentage is captured,” said Peter Skelton of Wrap, the UK government-funded Waste and Resources Action Programme. “In theory bioplastics are good. But in practice there are lots of barriers.”

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