*This Memorandum is based on the report of a WHO Consultation, convened in cooperation with the International Atomic Energy Agency (IAEA), which met in Neuherberg/Munich, Federal Republic of Germany on 13-17 November 1989. The participants were A.M.I. Alsayyed, Doha, Qatar; K.J. Dale, London, England; J.F. Diehl, Karlsruhe, Federal Republic of Germany; J. Farkas, Budapest, Hungary (Rapporteur); M. Frissel, Bilthoven, Netherlands; H. Fröhlich, Frankfurt, Federal Republic of Germany; J.H. Hubbel, Gaithersburg, MD, USA (Chairman); J.R. Lujan, Mexico DF, Mexico; and G. Pauli, Washington, DC, USA. Secretariat: K.W. Bögl, Berlin (West); A. Brynjolfsson, Wageningen, Netherlands; F.K. Käferstein, WHO (Secretary); A.-M. Schmitt-Hannig, IAEA; R.B. Singh, London, England; and H. Stiff, WHO. Joint FAO/WHO Food Standards Programme: E. Casadei, FAO, Rome, Italy. In addition, companies interested in X-ray surveillance equipment were represented by G. Geus and C. Koch, Wiesbaden, Federal Republic of Germany; C.T. Blunden and G. Bennet, Bristol, England; and C.S. Nunan, Palo Alto, CA, USA. Requests for reprints should be sent to Dr F.K. Käferstein, Food Safety Unit, Division of Environmental Health, World Health Organization, 1211 Geneva 27, Switzerland. A French translation of this Memorandum will appear in a later issue of the Bulletin.