Département santé environnement, Institut de veille sanitaire, 12, rue du Val-d’Osne, 94415 Saint-Maurice cedex France, Cellule interrégionale d’épidémiologie (Cire) Sud, Drass PACA, 23-25, rue Borde, 13285 Marseille cedex 08 France, Direction départementale des affaires sanitaires et sociales (DDASS) des Bouches-du-Rhône, 66 A, rue Saint-Sébastien, 13281 Marseille cedex 06 France, Institut français de recherche pour l’exploitation de la mer (Ifremer), Laboratoire Environnement Ressources Provence Azur Corse Z.P. de Bregaillon, BP 330, 83507 La-Seyne-sur-Mer cedex France, Institut français de recherche pour l’exploitation de la mer (Ifremer), Station de Corse, Z.I. de Furiani, Immeuble Agostini, 20600 Bastia France, Centre antipoison et de toxicovigilance de Marseille, Hôpital Salvator, 249, boulevard Sainte-Marguerite 13274 Marseille cedex 09 France
An initial surveillance system of Ostreopsis ovata was set up along the Mediterranean coast in the summer of 2007. To strengthen and adapt this system, we reviewed the information available for a health risk assessment of this monocellular species of algae that produces palytoxin and is increasingly observed in the Mediterranean Sea. Since 2002, this species has been reported to be responsible for many human cases of irritation, cough, fever and respiratory problems in Europe. It is not currently possible to determine if palytoxin causes these health effects, which follow aerosol inhalation. Ingestion of contaminated seafood may lead to very serious poisoning, but no such case has yet been described in Europe. A “dose-response” relation cannot be determined from the available data. For this reason, the threshold concentration of these microalgae in water was determined empirically for this public health intervention. Similarly, no studies have linked human exposure or effects to any particular quantity of microalgae or any given palytoxin concentration. We can, however, now describe the conditions under which these microalgae bloom and the situations when populations are exposed. More data are essential before a quantitative risk assessment can be performed. Research must be encouraged to help to determine the factors influencing blooms, which would facilitate the identification of risk zones and periods and the development of tools to predict blooms. We could then develop a sample-selection strategy to improve surveillance, focused on the zones where the population is exposed.