A British firm says it has discovered how to make a significant reduction in the amount of waste people throw away.

The BBC's Margaret Gilmore: "New plastic degrades to leave water and carbon dioxide"

The firm, Symphony Environmental Ltd, of Hertfordshire, has produced a new sort of plastic that will degrade completely - in other words, it will self-destruct.

The company says the plastic can be manufactured to rot away in as little as 60 days, or as long as five to six years.

And when it has degraded, the new plastic is said to leave behind nothing but water, carbon dioxide (CO2), and what its makers call "existing minerals".

CO2 is the most significant global warming gas produced by human activities.

Dr David Wiles of Symphony Environmental Ltd: "Scientific breakthrough"

The firm told BBC News Online that the amount of CO2 its new product will emit as it degrades is "no more than a person eating a slice of bread".

And unlike a similar plastic that appeared a few years ago, Symphony says this version will not produce another greenhouse gas, methane.

More space to tip

With the United Kingdom disposing of about 120 m tonnes of waste a year, of which 1 m tonnes are plastic, Symphony says its product will make a big difference.

It can be used in waste tips ("landfills"), in incinerators, and for composting.

The firm says the new plastic will represent a 20% to 30% increase in the capacity of landfill sites.

Some environmental groups, like Friends of the Earth, say the plastic is a step forward.

But others are puzzled, and say they need to know more before they can give it the thumbs up.

There could be gains for gardeners

Tony Hirons, of the Institute of Wastes Management, is unclear what the plastic is, and what it is for.

"If you can put compostable material into this, that will be a major benefit", he says.

But if the plastic is going to an incinerator, then Mr Hirons foresees a problem.

"Incinerator operators have worked out carefully the water content of the material they'll be burning.

"If this product gives off water, they'll have a lot of work to make sure it's suitable."

And he is not at all sure that there is much future for biodegradable plastic in landfill sites.

Change on the way

"At present, landfills operate what is called 'co-disposal' - different sorts of waste are buried together in the same hole, with biodegradable material helping to break down the rest.

"But before long the EU landfill directive will ban co-disposal", says Mr Hirons.

"Everything that goes into a landfill for biodegradable waste will have to be capable of breaking down like this new plastic.