London

Walls have ears, and soon they could have the burnt remains of snouts, bones and skin as well. No longer able to feed meat-and-bone meal (MBM) to farm animals, British researchers are assessing its potential as a construction material.

The Meat and Livestock Commission has asked engineers at the Building Research Establishment (BRE) in Watford, near London, to investigate whether ash from incinerated MBM can be mixed into concrete and used to fill holes, lay roads and even build houses.

About 2.5 million tonnes of MBM are produced in Europe each year as a by-product of the meat trade. MBM was used in animal feed in Britain until 1996, when the practice was banned because the feed was thought to be playing a role in the spread of mad-cow disease.

Slaughterhouses are now left with mountains of animal leftovers that they currently incinerate and pay to dump as landfill.

The industry is keen to find cheaper ways to dispose of this unwanted legacy. One option is to use the MBM ash as an alternative 'aggregate' — material such as crushed stone and gravel that is used to make concrete. Ash from domestic incinerators is already used to make concrete in some European countries.

“The construction industry could basically have the stuff for free if it helped to offset disposal costs,” says Martin Grantley-Smith, head of planning at the Meat and Livestock Commission in Milton Keynes.

Next month, a BRE team will start testing the mechanical strength of concrete made with the animal ash, and will see if any substances leach out. Ash has a different density and chemical composition depending on the burnt material.

“MBM ash contains a lot of calcium phosphate, not surprisingly because that's what bones are made of,” says Rod Collins, who heads the BRE team. He adds that the MBM ash could possibly be used in construction, but acknowledges that people might not accept materials containing MBM in housing.

Collins is confident that the infectious agent that may cause mad-cow disease will not be a problem, however, as it should be destroyed in the incinerator. “You can never be absolutely certain,” he admits. “But we're as sure as we can be that the material would be safe.”