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shellfish production sites as well as for importation of shellfish. In Denmark, The Netherlands
and Spain the mouse bioassay method established "no detectable amount". In France the
mouse bioassay established a tolerance of 0.044 MU/g digestive glands (Marcaillon-Le Baut and
Masselin, 1990), while in Japan with another principle for MU calculation the level is 5 MU/100
g soft tissue and this so in Norway (Yasumoto et al., 1984; Underdal, 1988). Sweden is the only
country in Europe which monitors shellfish for DSP by the HPLC procedure (Lee et al., 1987)
and is maintaining a tolerance level of 60 µg/100 g soft tissue (as okadaic acid and DTX-1). In
Italy DSP toxins were determined using the method established by the Ministerial Decree dated
1.9.90 (Ministero della Sanità, 1990c) similar to the official method used in France. The mice
were observed for 24 hr and positive test consists in T