Bio plastic

Eco-friendly bio-plastics made from plants cause environmental problems, according to a recent study.

The substitute for conventional oil-based plastic can increase emissions of greenhouse gases on landfill sites as some need high temperatures to decompose and others cannot be recycled, the study said. Many of the bio-plastics are also contributing to the global food crisis by taking over large areas of land previously used to grow crops for human consumption. Bio-plastics are made from maize, sugarcane, wheat and other crops, it added.

The industry, which used words such as ''sustainable'', ''bio degradable'', ''compost able'' and ''recyclable'' to describe its products, claimed bio-plastics could save carbon up to 30-80 per cent compared with conventional oil-based plastics and can extend the shelf-life of food.

Some of the biggest supermarkets and food companies were using a corn-based packaging made with polylactic acid (Pla), which looks identical to conventional polyethylene terephthalate (Pet) plastic.

The product has been used to package organic foods, salads, snacks, desserts, fruits and vegetables and bottles mineral water as well.

While Pla was said to offer more disposal options, it has been found that it would barely break down on landfill sites, and could only be composted in the handful of anaerobic digesters which exist in Britain, but which do not take any packaging.

These new generations 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.
''A significant percentage leaks to the atmosphere,'' the Guardian quoted him as saying.

''Just because its 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 Programmed.

Some environmentalists said the terminology confused the public.

''The consumer is baffled,'' a Wrap briefing paper said. ''It considers these products degradable but ... they will not degrade effectively in (the closed environment of) a landfill site,'' it added.