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<P>In order to minimize cross-contamination, it is necessary to determine the routes through which it could occur, and the importance of each of the routes. Through monitoring CNS dispersion under research and commercial abattoir conditions, it is anticipated that best practices and critical points in existing procedures can be identified.</P>
<P>Protein antigen-based (ELISA) assays will be used to monitor cross-contamination of carcasses, equipment and abattoir environment (including atmospheric) with CNS material during conventional slaughter, dressing and butchery of cattle and sheep, in order to identify critical practices. Based on the results of these studies, changes to conventional methods will be tested under experimental conditions to ascertain whether cross-contamination can be reduced. Concurrently, innovative equipment (particularly saws and vacuum devices) will be developed and tested for their ability to reduce or eliminate cross-contamination. A set of guidelines for avoidance of CNS cross-contamination in the meat industry will be drafted for presentation to the EC.</P>
<P>The principle sites of infectivity in mammalian species carrying TSEs are in the brain and spinal cord. To reduce the risk of transfer of TSE infectivity from meat to man, these tissues have been excluded from entering the food chain. However, conventional slaughter and butchery practice could enable these tissues to cross-contaminate the meat and meat plant environment. Risks are different in different species, bovine carcasses being conventionally split down the median sagittal plane at the end of dressing, thus exposing the spinal cord, whilst the majority of young sheep carcasses are despatched in entire form from the abattoir, and currently contain the spinal cord.</P>
<P>Cross-contamination is important because of the increasing public concern over food safety; and it may be direct, that is between constituent parts of a carcass and its meat, or indirect, that is from a source on one carcass to another via some route involving the environment, operator or implement. </P>