The latest food scare frenzy is best demonstrated by this headline: KFC hit by cancer-causing red dye scare in China.

Kentucky Fried Chicken (KFC) outlets in China have stopped selling their New Orleans roast chicken wings and chicken hamburgers after a cancer-causing food coloring, Sudan I, was found in the sauce, state media said..."We feel deep sorry for this food safety accident and promise it will never happen again," Xinhua quoted the statement as saying.

Sudan I is a red dye traditionally used for coloring solvents, oils, waxes, petrol and shoe and floor polishes. It cannot safely be used in food as it can increase the risk of cancer.

Sudan 1 is a genotoxic carcinogen, which means that it can permanently alter the DNA in, say, a human liver cell. The study that links Sudan 1 to cancerous tumours was done in America 20 years ago. It found that when rats and mice were fed 30mg of Sudan 1 for each kilogram of their bodyweight every day for two years, the rats underwent changes that indicated they were on the way to getting tumours. The mice were okay. The study was peer reviewed, but was never replicated. When the International Agency for Research on Cancer looked at the data, it decided it was not robust enough to categorise Sudan 1 as a likely cause of cancer, says Alan Boobis, a toxicologist at Imperial College, London. He likens the risk of getting cancer from the affected food products to that from smoking one cigarette in a lifetime.

If an average-sized man, who weighed 80kg (12½ stone), volunteered to test the effects of Sudan 1 on humans, he would have to consume 2.4 grams of the dye a day to match the dose given to the rats. According to the Food Standards Agency (FSA), there are 3mg of Sudan 1 in every litre of the contaminated Worcester sauce. So our man would have to drink around 800 litres of Worcester sauce every day for two years. That's an awful lot of Bloody Marys.