Q&A: Drugs in poultry

The Soil Association has raised concerns about the level of drug residues in chicken and eggs.

BBC News Online looks at what the drugs are used for and how they might get into our food.

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What drugs are used in poultry farming?

A range of drugs - mainly antibiotics and anti-parasitic treatments - are used routinely in intensive poultry farming. They are given to the birds in their feed or water.

The Soil Association says it is most concerned about drugs used to control intestinal parasites in poultry and game birds.

These include nicarbazin, lasalocid and dimetridazole. Nicarbazin and lasalocid, both used to treat a parasitic infection known as coccidiosis, are given in feed.

Dimetridazole is another anti-parasitic drug, given to birds in their water.

Why is lasalocid a potential problem?

The latest Soil Association investigation focuses specificaly on the antibiotic lasalocid.

The chemical is too toxic to ever be used in medicine and has been shown to have potent effects on animals at low levels.

Rabbit hearts contract when exposed to the drug ¿ a discovery which prompted an experiment in 1974 using human heart muscle.

Rapid contractions were observed and were still evident an hour after the drug had been given.

Alison Craig, of the Soil Association, said "Even low levels of lasalocid are dangerous to mammals and this raises concerns about how toxic the drug is to humans.

"We know that this drug hangs around in the body, so we could be accumulating it every time we eat eggs or chicken."

How might these drugs get into human food?

The drugs are given to poultry in the first three weeks of life but must be withdrawn before the birds are sent to slaughter or before they lay eggs.

Most drugs must be stopped for eight days before the animal's meat or eggs enter the human food chain.

This should stop any traces of medicine, which might remain in the animal's body, from getting into human food.

The Veterinary Medicines Directorate (MVD), an executive agency of Maff, is responsible for monitoring for the presence of residues in meat and eggs.

According to the VMD, in 1999, 8,063 poultry samples were tested for all likely contaminants. Of these 99.3% were "free of detectable residues".

But the Soil Association disputes these figures, and has claimed that residue levels may be up to 2,000% higher than the officially recognised levels.

Alastair Johnston, of the British Veterinary Poultry Association (BVPA) says the UK is doing its best to minimise the use of anti-parasitic and antibiotic drugs.

He told BBC News Online: "As long as we aim to obey the withdrawal periods and maintain the standard of regulation concerning poultry drugs and antibiotics in the UK, then I think the poultry and eggs in the UK are the safest in the world."

Why are the drugs needed?

The Soil Association says that the use of such drugs has its roots in intensive farming methods.

It says that unnatural feeding practices and the unsanitary, overcrowded, moist, dark, confined conditions in which large numbers of chickens are kept would inevitably lead to most of the birds perishing without drugs to keep them alive until they are ready for slaughter.

But Alastair Johnston, said the health and welfare of birds would deteriorate if anti-parasitic and antibiotic products were not used, even in free-range conditions.

Less drugs would be needed for free range chickens, he said - but they would still be needed to control disease.