Science - January 20, 2005

Quicker dioxin detection useful in crisis

Recently developed methods for tracing dioxin in food are cheaper and quicker than the traditional method, and will therefore be valuable in times of crisis. The reliability of the methods is not yet good enough however.

Rivo and Rikilt from Wageningen UR participated in a recently held symposium on dioxin detection in Brussels, together with their Swedish, Belgian and Spanish counterparts in the Difference-project. This EU project was started in response to the Belgian dioxin crisis in 1999, when it became clear that laboratories did not have enough capacity to check for dioxin presence in chicken, eggs and other foods.

During the symposium it emerged that the bioassay (the Calux method) and two instrumental techniques are good alternatives to the traditional method for detecting dioxin: gas chromatography combined with high-resolution mass spectrometry. With the old method it can take a laboratory worker eight days to check ten or twelve samples for the presence of dioxins. The bioassay can check seventy-five samples in a day. The test is done using an animal cell culture, and makes use of the principle that dioxins attach themselves to a receptor in animal cells. Professor Leo Goeyens of the Scientific Institute for Public Health in Belgium, Dr Jacob de Boer of Rivo and Wim Traag of Rikilt all agreed that the Calux bioassay increases capacity for checking foods by a considerable amount. It is therefore unlikely that laboratories will be faced with having to refuse samples for testing due to limited capacity as happened in Belgium, and it was agreed that the new methods would increase food safety.

The researchers admitted however that the bioassay developed, that is much cheaper than the traditional method, is sensitive to disturbances from other substances that may be present in the sample and can therefore suppress or enhance the signal measured. During the validation study a small number of cases were observed where the results diverged from the reference method. Further research on the influence of other substances on the bioassay signal is therefore necessary to increase the reliability of the method. / HB

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