Experts are calling for urgent action to investigate the theoretical risk of UK abattoirs being contaminated with mad cow disease.
Scientists from the Royal Society and the Academy of Medical Sciences, who published the Transmissible Spongiform Encephalopathies report, are calling for new measures to prevent any risk of cross-infection.
Cattle over the age of 30 months, which might be infected with BSE, are routinely slaughtered and prevented from entering the human food chain.
Contamination fears
Some slaughterhouses contracted to carry out the culling also produce meat destined for butchers and supermarkets.
Abattoirs are forbidden from carrying out both activities on the same day, under European Union rules.
But this does not rule out the possibility of cross-contamination, according to the report's authors.
Brian Heap, vice-president of the Royal Society, said: "Urgent consideration needs to be given to the possibility of cross-infection in the few abattoirs in the UK that handle both the slaughter of animals for food and the culling of cattle aged over 30 months that may be incubating BSE."
He said there was some evidence that prions - agents thought to transmit BSE and related diseases - might still be active even after heating to 600 C.
"Since cattle aged over 30 months are culled because they might be infected with BSE, we need to establish conclusively that work surfaces and equipment in abattoirs are not contaminated after the usual cleaning and sterilisation procedures," said Professor Heap, who chaired the working group.
Disposal backlog
The report also highlights the risk posed by the backlog of potentially-infected material building up in storage hangers.
More than 430,000 tonnes of meat and bone meal, and a further 200,000 tonnes of tallow, are currently awaiting safe disposal in the UK.
"There is always a danger of leaks into the environment through, for example, infestation of rodents or invertebrates," says the report.
The Consumers' Association says the Food Standards Agency should urgently investigate the concerns raised by the report and ensure that any risk of cross-contamination in slaughterhouses is prevented.
"Given the spread of BSE across Europe, it's also essential that the European Commission acts on the concerns that have been highlighted," the Consumers' Association adds.
"This report reiterates the importance of constantly keeping potential routes of infectivity and BSE control measures under review."