ePO 40 – Tetrodotoxins in bivalve species from the algarve coast (southern portugal)

Introduction Tetrodotoxin (TTX) is a potent neurotoxin, first identified in fish from the Tetraodontidae family. A Human poisoning episode after consumption of trumpet shell Charonia lampas in Spain, together with the increasing reports of TTX in bivalves from European waters, led the European Food Safety Authority to recommend maximum safe limits for Human consumption of shellfish meat. However, TTX is currently only monitored in the Netherlands and France. On the southern coast (Algarve) of Portugal, TTX concentrations were detected in trumpet shells exceeding the levels considered safe for human consumption throughout the year. Nevertheless, there are no data on the incidence of TTX in bivalve species from this area where contaminated trumpet shells were caught. Objectives and methods. This study assessed the presence of TTX and its 30 chemical congeners in 25 bivalve species from this coastal area. Bivalves were collected within the framework of the monitoring bivalve dredge fishing survey coordinated by the Portuguese Institute for the Sea and Atmosphere. Samples were extracted and analysed using liquid chromatography–high resolution mass spectrometry according to the Standard Operating Procedure of the European Union Reference Laboratory for Marine Biotoxins. Discussion and conclusions.  TTX itself was either not detected or was present at concentrations considered safe for human consumption. However, TTX congeners, whose toxicity is estimated rather than fully characterized, were also detected, which may increase the potential risk of intoxication and raise concerns for public health. Moreover, the origin of TTXs remains uncertain, with current evidence suggesting that they are synthesized by bacteria and accumulate through the food web. Understanding the pathways of TTXs introduction and accumulation in bivalves is essential to accurately assess the risks associated with its consumption and to inform effective monitoring and management strategies.