Organochlorine pesticides are determined in a number of marine environmental matrices by laboratories of member states. An RM is urgently needed for these measurements in marine monitoring programmes of the Oslo and Paris commission and the North Sea task force.

A fish oil containing indigenous levels of organochlorine pesticides which represent a medium level of contamination will therefore be prepared and stabilised with antioxidant. After ampouling, homogeneity and stability trials the group of expert laboratories will undertake a programme of certification.