Evaluation of the prevalence of Paralytic Shellfish Toxins in non-traditional vectors and potential health risks associated to their consumption

Paralytic shellfish toxins (PSTs) are potent marine neurotoxins mainly associated with dinoflagellates. European Union (EU) Regulation Nº 853/2004 and its amendments establish the maximum permitted levels for PSTs in bivalve molluscs, echinoderms, tunicates and gastropods. In Europe, the analyses of marine biotoxins for monitoring purposes is mainly focused on bivalve molluscs. Other vectors, including some from the regulated groups, are rarely covered by monitoring programs. The aim of this study is to estimate the prevalence of PSTs across species from eight marine invertebrate groups and fish in Galicia (NW Spain). In total, 533 invertebrates (echinoderms, gastropods, cnidarians, crustaceans, cephalopods, polychaetes, tunicates, porifera and bivalves) and 96 fish samples were collected between April 2021 and September 2023 and analysed using both LC-FLD and LC-MS/MS methods. PSTs were detected in 265 samples in all groups except cephalopods and tunicates. Quantifiable levels were found in 233 samples. Our results show the existence of potential PST vectors other than bivalves, including edible organisms of great economic value. These findings could be extrapolated to other countries with similar harmful algae events and stress the need for further surveys on different groups of marine invertebrates for a better public health protection. To our knowledge, this is the first report of PSTs in Littorina spp., Nassarius spp., Patella ulyssiponensis , Balanus spp., Carcinus maenas , Luidia sarsi and Ophiotrix spp. in the EU. Moreover, PSTs are also described for the first time in Nucella spp., Patella spp. and Polybius henslowii from Spain. • This is the first comprehensive study of PSTs conducted in non-bivalve invertebrates from the Galician coast. • PSTs were detected in 50 % of the samples analysed. • Cnidarians, crustaceans, echinoderms, gastropods, polychaetes and porifera were found to contain PSTs. • In some cases, results from parallel mussel samples did not correlate well with other invertebrates. • Some edible invertebrates should be concern to surveillance programmes and deserve public health protection measures.