A long-abandoned factory and woodlands could still pose a “biohazard” to humans - as experts warn soil and water may be contaminated with Mad Cow Disease.

Thruxted Mill, between Ashford and Canterbury, was one of five sites used in the UK to dispose of the remains of cattle infected with the illness, also known as Bovine Spongiform Encephalopathy (BSE).

But now a scientific paper says the derelict seven-acre complex may still threaten people’s safety - with one of its authors, Prof Alan Colchester, even warning against housing developments on the land.

The University of Kent academic believes the former animal-rendering plant is dangerous because the molecules that cause BSE - as well as the human form of the disease - are incredibly hard to destroy.

“The site is a biohazard,” the Professor Emeritus of clinical neuroscience said.

“It’s always been known that the infected agents for Mad Cow Disease are incredibly resistant to normal decay and destruction and there will undoubtedly be some long-term contamination in the soil.

“The point is that there are various ways you could come into contact with it.”

In the 1990s and noughties, truckloads of animal remains were ferried to the site between Chartham and Godmersham, where machines separated animal fats and protein residue from the bone.

There were reports of piles of carcasses regularly being dumped in the yard area and a pungent smell hanging over the countryside. It was not uncommon for the surrounding routes to become littered with chunks of dead cattle.

In 2008, a lost lorry trying to find its way to the mill spilled tongues and lumps of a bladder the size of a football in Beech Avenue, Chartham.

Villager Peter Hancox said at the time the route “frequently had fluid spillages, but this was one lump of guts too far - the smell was horrible”.

The derelict mill has been described as the perfect site to film a horror movie.

The symptoms of the disease passed on to humans - called CJD - include memory loss, personality changes, abnormal jerking movements and a loss of brain function and mobility.

“The worst-case scenario is that you could transmit the illness to animals or humans from environmental materials that have themselves been infected in the past,” Prof Colchester added.

“And with CJD, we’re talking about a seriously long incubation period - from a few months to several years.”

In 1998, Prof Colchester, a consultant neurologist at Guy’s Hospital in London at the time, said “infected remains were left lying around and contaminated material is probably still lying in large quantities in the soil”.

Despite this, developers hoping to build 20 homes pledged to decontaminate the site at an estimated cost of £1.75 million in 2017.

They stressed how soil studies showed evidence of matter including asbestos, metals, petroleum oils and fats. No microbiological species, such as anthrax or salmonella, were found.

In determining the scheme, Ashford Borough Council recognised how the old mill “had the most dreadful legacy” and gave it the green light.

But following a legal fight led by disgruntled resident Camilla Swire - whose daughter Eleanor worked on the recent study with Prof Colchester - the authority’s ruling was overturned due to a lack of “expert evidence”.

An environmental impact assessment was required, but a year later the application was pulled.

And Prof Colchester’s paper “Out of sight, out of mind? BSE 30 years on” - which was published in the academic journal Land Use Policy - warns against any residential or recreational developments on such sites.

“Nothing should be done to encourage human activity around Thruxted Mill or the surrounding woodlands,” continued Prof Colchester.

“If you have places in an urban environment that has contamination, then there might be a case that we should tarmac it over completely.”

Thought to have originally been developed as a saw mill in the 1960s, Thruxted was transformed into the animal-rendering plant by Canterbury Mills Ltd. Documents on Companies House show the firm was dissolved in 2010, two years after the closure of the factory.

A spokesman for the Department for Environment, Food and Rural Affairs said: “To prevent risks of spreading disease from residues in the soil, groundwater or air pollution, the burial or burning of fallen stock, including all farmed animals, in the open has been banned since 2003.

“Before that, guidance on the safe and legal disposal of fallen stock was made readily available.

"The risk of biohazards are addressed through local authority planning processes if historic burial sites are redeveloped.”