Palytoxin (PLTX), identified in Palythoa corals, Ostreopsis dinoflagellates, and Trichodesmium cyanobacteria, is considered one of the most complicate and toxic molecules found in nature. The recent appearance of Ostreopsis spp. in the Mediterranean Sea as well as the uncontrolled diffusion of Palythoa corals, widely used as aquarium decorative elements, pose serious concerns for human health. The concomitant detection of putative PLTX and of PLTX analogues poses new problems regarding the toxicological potential of PLTXs, already known for their high toxicity since the 1970s. In general, adverse effects in humans can occur through different exposureroutes: ingestion, dermal, inhalational, or ocular exposure. Among them, oral exposure after ingestion of contaminated seafood is the most dangerous one for human health, although it seems to be limited to tropical and subtropical regions. On the contrary, in temperate areas, such as the Mediterranean Sea, human intoxications are frequently associated with inhalational exposure to aerosolized seawater during Ostreopsis blooms. In vivo toxicity studies indicate that the toxicity of PLTX by oral route is lower than that after parenteral injection, but the European Food Safety Authority suggested an admissible limit of 30 μg PLTX/kg shellfish meat. Also the potential toxicity of PLTXs after aerosol exposure needs to be urgently addressed due to increasing blooms of Ostreopsis associated with respiratory and ocular problems as well as dermotoxicity in people exposed to seawater both for recreational and working activities.
