Residue data on several contaminants (organochlorine pesticides, PCBs, lead, cadmium, and aflatoxins) in selected foods were collected from designated Collaborating Centres in twenty countries during a preliminary or development phase of this contaminant monitoring programme. These data are given in this document for each Collaborating Centre according to the contaminant analyzed in the food selected. The data include that submitted in the initial stage of the programme which was reviewed in the Summary Report