BSE controls final report, 20 December 2000, section 2, Risk and uncertainty
5. Perhaps more than in any other area of food safety, BSE is characterised by scientific uncertainty. Although two Nobel Prizes have been awarded for research on the family of diseases to which BSE belongs, Transmissible Spongiform Encephalopathies (TSEs) or Prion Diseases, it is probably fair to say that there is still uncertainty about most aspects of BSE. The precise nature of the causative agent and how it spreads in the host is not known for certain. Nor is it known definitely why it became evident in cattle in the UK in the mid 1980s and the knowledge about its routes of transmission within the cattle population is incomplete. Whilst the evidence that the same agent causes BSE in cattle and variant Creutzfeldt Jakob Disease (vCJD) in humans is now generally accepted as conclusive, the evidence that the vCJD epidemic is due to exposure to this agent via the food chain is circumstantial, albeit strong. An important additional uncertainty as far as the food chain is concerned is the extent and nature of the species barrier, which varies between different pairs of species. It also affects significantly our ability to predict the degree of infectivity of the agent. We do know that following the onset of clinical symptoms vCJD is uniformly fatal at present, although research to find a treatment is ongoing.
6.These many areas of uncertainty mean that the current risk management options for protecting the health of the public are precautionary in nature and are aimed at risk reduction in the light of current knowledge, recognising that risks may not be totally eliminated. Indeed, as the BSE Inquiry report makes clear, it is not possible for any controls to be sufficiently rigorously enforced that they will eliminate all risk. The options need to be continually reassessed as new research results become available, and it is in this context that our review was carried out. The FSA will have to continue to evaluate the controls as evidence emerges.