Millions of cows were destroyed following the Bovine Spongiform Encephalopathy (BSE) epidemic, but a lack of incinerator capacity to properly dispose of the infected animals meant over 6,000 were buried in mass graves at almost 60 sites around the country.
Government health officials were criticised for the move after it emerged the highly infectious spinal cords were not amputated before the carcasses were interred.
And researchers at Edinburgh University’s Roslin Institute now believe prions - the proteins responsible for causing the condition - can remain toxic for “very long periods of time,” adding they could be washed through soil by rainwater.
The study, funded by the Department for Environment, Food and Rural Affairs (Defra), added bodies of water near to the burial pits could have been polluted as a result.
Scientists from the Institute partnered with researchers from the University of Nottingham for the study, which injected bovine skulls and brain tissue with prion disease and buried them in a controlled environment.
The migration of the proteins was then measured over a five-year period.
The study said: “We have shown that high levels of infectivity can, and probably in most circumstances do, survive in brain tissue underground for very long periods of time — at least five years in this case — without significant loss of infectivity.”
“These results should be taken into account when considering the future use and possible remediation of sites where BSE infectivity has been deposited. It should be assumed that high levels of BSE remain even after many years.”
An estimated 180,000 animals were infected with BSE at the peak of the crisis in 1993, thought to have been caused by feeding bovine meat and bone meal to cattle.
It emerged the disease had jumped the species barrier to humans in 1996 through the consumption of contaminated beef.
Since then, around 180 people were confirmed to have died of variant Creutzfeldt-Jakob disease (vCJD), the human form of the condition.
In October 2018, an infected cow was discovered on a farm in Lumsden, Aberdeenshire, the first confirmed case of BSE in Scotland in a decade. A total of 16 cases have been reported across the UK since 2011.
A spokeswoman for Defra said: “While the number of new cases of BSE in the UK in the past few years has been extremely low, we continue to have strict controls in place to protect the public and animals, and ultimately help eradicate this disease.”
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