Ostreospis cf. ovata blooms in coastal water: Italian guidelines to assess and manage the risk associated to bathing waters and recreational activities

Ostreopsis cf. ovata is a benthic marine dinoflagellate, which blooms in summer along the coasts of the Mediterranean Sea, including many Italian regions since early 1990s. In tropical areas O. cf. ovata produces mainly palytoxins whereas in the Mediterranean basin it produces ovatoxins, and only trace amounts of a putative palytoxin. The toxicological profile of ovatoxins is still unknown. This paper describes the update of the Italian guidelines for the management of O. cf. ovata blooms related to bathing and recreational activities. The rationale for the guidelines starts from the current scientific knowledge on chemical, toxicological, and epidemiological aspects and on its diffusion, which are briefly summarized in the first part of the paper. On this basis a risk-based approach is developed, with the purpose to protect people from oral, dermal and inhalation exposure (the ones that so far caused major health problems), taking into account also the weather and sea conditions, which are crucial for the onset of blooms. Accordingly, the guidelines provide information on what indicators are needed to set up environmental monitoring activities and actions to take during diverse phases. They also outline a multi-step health surveillance system, and a system of communication to the public. Finally the still important scientific gaps and research needs are highlighted.