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Last Updated: Tuesday, 22 February, 2005, 11:23 GMT
Illegal dye: What is the health risk?
Rats given Sudan 1 developed tumours
The contamination of food with an illegal dye has triggered the UK's biggest ever recall of products.

There is concern that the dye, Sudan I, has the potential to cause cancer.

However, the Food Standards Agency has said the risk is very low.

Professor Alan Boobis, an expert in toxicology at Imperial College London says there is little reason for the public to be alarmed.

People should not be unduly concerned about the health effects
Professor Alan Boobis
Sudan I was banned from use in food products following experiments on rats, which suggested that the chemical could trigger the formation of malignant tumours.

However, Professor Boobis told the BBC News website that the levels of the chemical fed to the rats bore no relation to the kind of levels that people would be exposed to if they ate contaminated products.

The rats who showed signs of developing tumours were given a daily dose of Sudan I of around 30 milligrams/kg of bodyweight for two years.

Animals given a lower dose - 15milligrams/kg of bodyweight - showed no signs of cancer-related changes.

The contaminated products would contain Sudan I doses of a much smaller magnitude - micrograms, rather than milligrams.

The animals that did show signs of cancer - known scientifically as tumourigenic changes - started to do so only after many months.

In human terms, this would suggest that if the dye was to have any effect, the symptoms would not start to become apparent for around 20 years.

Genetic damage

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The compound triggers cancer growth through what is known as a DNA reactive mechanism.

Within the body it is converted into a form which attacks the DNA of cells, causing damage which can be passed on to the next generation of cells in the affected tissue, ultimately leading to cancer.

However, Professor Boobis said that the risk of eating just one or two contaminated items was trivial.

While not an exact comparison, he likened it to the cancer risk associated with smoking just one cigarette in a lifetime.

Even if a person was to eat a contaminated product every day for several years, the risk of cancer, although higher, was still likely to be very low.

"This compound is not a very potent carcinogen in animals," he said.

"People should not be unduly concerned about the health effects.

"It is a good idea to remove this substance from the food chain, but this is being done simply as a precaution, not because there is an immediate impact on health."

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