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E. coli danger stalks farmland sewage sludge

HUMAN INFECTION from deadly pathogens including the feared E. coli O157 bacteria could be linked to the spreading of sewage sludge on farmland, a government report is expected to confirm this week.

Scientists working on the review of the code of practice for the agricultural use of sludge warned that there are also concerns over the risk of entero viruses and a potentially lethal form of salmonella, known as serotype DT104, being passed to humans through grazing cattle.

And with new government regulations set to ban sludge dumping at sea by the end of this year, it is feared that more of the toxic waste product will end up spread on the UK's farmland.

Severn Trent Water's sludge planning manager Chris Rowlands confirmed that the industry was concerned about the practice. 'There is an anxiety that these pathogens may be viable in the environment for a long time and may produce a risk to humans,' he said.

Although 98% of sewage sludge spread to land is 'treated', the latest research shows that some organisms may survive the process. Bacteria like E. coli O157 are particularly dangerous as only 10 to 50 cells are needed to produce infection.

But Rowlands stressed: 'What we're talking about is a very, very low risk indeed. The existing code of practice has been in place since 1989 and there has been no reported disease in either livestock or humans.'

Present guidelines advise farmers to keep livestock off fields for three weeks after spreading sludge. But laboratory trials by the Centre for Applied Microbiology and Research at Porton Down have shown that E. coli O157 can survive in the environment for up to 140 days.

CAMR microbiologist Dr. Andy Maul said: 'The results indicate that the organism survives well in model soil systems. We now need to determine how long it survives in practice.'

Under the 1994 Urban Wastewater Treatment regulations, all water companies must stop sludge dumping at sea by the end of the year. The high cost of landfill disposal and need to reduce carbon dioxide emissions from incineration are likely to mean a significant increase in the disposal of sludge to land.

The review of the practice, carried out by UK Water Industry Research for the Department of Health, Department of the Environment, Transport and the Regions and Ministry of Agriculture Food and Fisheries, is ex- pected to form the basis of the government response to a select committee report published in February.

Matthew Jones

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