Twenty-eight local authorities across the UK will take a total of 224 samples, and results are due to be published in April.

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In the traditional model of medicine, a doctor takes samples, has these analysed and uses the results to diagnose the presence of a disease.

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Analysis on worldwide DNA samples suggested the results were similar regardless of a person's geographic ancestry.

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The results, based on test performances of samples of 9, 13 and 17 year olds, suggest that apart from maths, average school standards have not risen since the early 1990s.

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Commenting on the latest results, Ireland's Agriculture Minister Simon Coveney said seven samples of raw ingredients had been tested, including one sourced from another European country that had tested positive.

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Today doctors must follow complicated steps to prepare samples, and 10% of DNA material is lost, ruining results.

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While some of the samples have tested negative for the rare strain of enterohaemorrhagic E. coli (EHEC), the results of other tests are still pending and expected later on Wednesday.

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