Palytoxins in Zoantharians and Seawater from Marine Home Aquaria. Comparison between Palythoa- and Ostreopsis- related Inhalatory Poisonings

Since the late 90s’, hundreds of cases of respiratory illness and/or dermatitis have been repeatedly recorded in people concomitantly with massive proliferations of the benthic dinoflagellate Ostreopsis cf. ovata in the Mediterranean area. Thanks to development of a liquid chromatography-high resolution mass spectrometry (LC-HRMS) method, we have characterized O. cf. ovata as a producer of congeners of palytoxin, a highly potent toxin whose inhalation hazard was however unknown. On the basis of the concomitance of Ostreopsis blooms, respiratory illness in humans, and detection of palytoxin congeners in algal samples, a cause and effect relationship between the cases of malaise and the algal toxins has been postulated but never substantiated. Further cases of respiratory illness tentatively attributed to palytoxins have been reported for aquarium hobbyists from incidental inhalation of steams generated during cleaning operations of home aquaria containing soft corals belonging to Palythoa genus. The only common feature between Palythoa spp. and Ostreopsis spp. is that both, although phylogenetically distinct, may produce palytoxins. The study reported herein serves the double purpose of demonstrating the presence of palytoxins in home marine aquaria involved in several inhalatory poisonings and of correlating the symptoms shown by patients while handling Palythoa spp. in home aquaria with those reported for Ostreopsis-related poisonings. From the chemical and symptomatological data, it is reasonable to hold palytoxins responsible for respiratory disorders following inhalation. Although the exact mechanism through which palytoxin congeners from Palythoa spp. and Ostreopsis spp. exert their inhalatory toxicity is still unknown, this represents a step toward inhalatory risk assessment of palytoxin congeners in domestic and open-air environments.