Sudan 1 is a dye to make chilli powder redder and is a weak carcinogen (Category 3 in IARC classification). Traces of the dye were found in a sauce in Italy. As a result, the UK Food Safety Agency (FSA) issued a notice in February 2005 that about 600 of products, including many pies and pizzas and other ready made meals, had to be taken off the shelves. This was the biggest recall of food ever - involving most of the big retailers in the UK and 15 countries other countries.

Sudan 1 was banned in the EU in 2003 (although banned in the USA since 1918). Traces of the dye were found and alerted the authorities of its possible presence in 1000’s of products. Government authorities said that there were no immediate risks to individuals, but there was a public health risk. Questions were raised as to why it took 2 years to find the dye, and why hadn’t it been spotted before by normal routine quality testing?

Asda withdrew 68 contaminated products, Waitrose took 54 products off its shelves. Sainsbury's, Morrisons and Tesco removed 41, 44, and 38 products respectively. Fast food chains like McDonald’s and Pret A Manger were also affected because their sauces were contaminated. The food recall, which has affected manufacturers like Heinz and Bird’s Eye, is estimated to cost more than £100 million. The recall eventaully hit China.

There is a maze of small businesses and export houses that work the world's commodity markets. It makes it almost impossible to trace the source of such "dirty" products. An Indian businessman is suspected of exporting the contaminated chilli powder to UK importers EW Spices, who then supplied five tonnes of chilli powder to an Essex-based company called East Anglian Food Ingredients. The chilli was sold on to another company called Unbar Rothon, which in turn supplied it to Premier Foods, claiming it was clear of the dye. Premier Foods added the contaminated chilli to Worcester sauce, which was used as a flavouring in the manufacture of top brand products. These products are all being recalled by the Food Safety Agency (FSA list)

The EU issued a Traceability Guide to help Food Firms understand and comply with the EU traceability laws.