(China Daily)
Updated: 2008-04-29 07:20

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.

A man pours oats into a plastic container at the opening of a new organic grocery store that requests customers to bring their own packaging last Novermber in London. The shop "rewards" shoppers with a discount for using their own containers. [Agencies]

The substitutes can increase emissions of greenhouse gases on landfill sites, while 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 to 30 percent a year.

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

Concern centers on corn-based packaging made with polylactic acid (PLA). Made from genetically modified (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 largest 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 114 million 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.

Last year, Innocent drinks stopped using PLA because commercial composting was "not yet a mainstream option" in the UK.

Anson, one of Britain's largest suppliers of plastic food packaging, switched back to conventional plastic after testing PLA in sandwich packs. Sainsbury's has decided not to use it, saying PLA is made with GM corn.

"No local authority is collecting compostable packaging at the moment. Composters do not want it," a spokesman said.

Britain's supermarkets compete to claim the greatest commitment to the environment with plant-based products. The bioplastics industry expects rising oil prices to help it compete with conventional plastics, with Europe using about 50,000 tonnes of bioplastics a year.

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."

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