91av

FIELDS across Europe are contaminated with dangerous levels of the antibiotics given to farm animals. The drugs, which are in manure sprayed onto fields as fertiliser, could be getting into our food and water, helping to create a new generation of antibiotic-resistant “superbugs”.

The warning comes from a researcher in Switzerland who looked at levels of the drugs in farm slurry. His findings are particularly shocking because Switzerland is one of the few countries to have banned antibiotics as growth promoters in animal feed.

Some 20,000 tonnes of antibiotics are used in the European Union and the US each year. More than half are given to farm animals to prevent disease and promote growth. But recent research has found a direct link between the increased use of these farmyard drugs and the appearance of antibiotic-resistant bugs that infect people.

Most researchers assumed that humans become infected with the resistant strains by eating contaminated meat. But far more of the drugs end up in manure than in meat products, says Stephan Mueller of the Swiss Federal Institute for Environmental Science and Technology in Dübendorf. And manure contains especially high levels of bugs that are resistant to antibiotics, he says.

With millions of tonnes of animal manure spread onto fields of crops such as wheat and barley each year, this pathway seems an equally likely route for spreading resistance, he told 91av. The drugs contaminate the crops, which are then eaten. They could also be leaching into tap water pumped from rocks beneath fertilised fields.

Mueller is particularly concerned about a group of antibiotics called sulphonamides. They do not easily degrade or dissolve in water. His analysis found that Swiss farm manure contains up to 20 parts per million of sulphonamides. That means each hectare of field could be contaminated with up to 1 kilogram of the drugs. “This concentration is high enough to trigger the development of resistance among bacteria, such as E. coli,” says Mueller. He says vets are not treating the issue seriously, and is calling for urgent action to reduce antibiotic use in animals, especially as growth promoters.

Two years ago, regulators in the US persuaded the EU to relax its rules on antibiotics in animal manure, allowing up to 75 grams of any one antibiotic onto each hectare of field (91av, 19 February 2000, p 20). But there are few checks, and Mueller’s findings suggest this figure may be widely breached.

There is growing concern at the extent to which drugs, including antibiotics, are polluting the environment. Many drugs given to humans are also excreted unchanged and are not broken down by conventional sewage treatment. Last week, Johns Hopkins University in Baltimore launched a programme to track 200 major drugs in the US.

Steve Killeen, head of chemicals policy at Britain’s Environment Agency, says his agency has worked hard to monitor levels of pharmaceuticals in the environment. But “animal antibiotics remains a blank spot for us. Very little research has been done.”