Evaluation of the Occurrence of Tetrodotoxin in Bivalve Mollusks from the Portuguese Coast

Susana Margarida Rodrigues,Estefanía Pereira Pinto,Patrícia Oliveira,Pedro Reis Costa,Sónia Pedro

doi:10.3390/jmse7070232

Susana Margarida Rodrigues, Estefanía Pereira Pinto + Show 3 more

Open Access

https://doi.org/10.3390/jmse7070232

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Abstract

Occurrence of tetrodotoxin (TTX), a potent natural neurotoxin, in marine organisms and seafood from the European Union has been of increasing concern due to its relatively recent detection in bivalve mollusks and gastropods. Following a request of the European Food Safety Authority (EFSA) to EU Member States to obtain more data on TTX occurrence, this study collected 117 samples of bivalve mollusks, including mussels (Mytilus galloprovincialis), oysters (Crassostrea gigas) and clams (Ruditapes philippinarum and Donax spp.), from the South and Southwest Portuguese coast between May and October 2018, for TTX determination and microbiological analysis. The analyses carried out by hydrophilic interaction liquid chromatography tandem mass spectrometry (HILIC-MS/MS) did not detect TTX in any sample, and microbiological analysis did not reveal high concentrations of Vibrio spp., which has been linked to the presence of TTX. Although preliminary, results from this study, the first investigating the presence of TTX in bivalve mollusks from the Portuguese coast, suggest that TTX may not represent a risk for human consumption of bivalve mollusks.

Highlights

Tetrodotoxin (TTX) is a potent neurotoxin that blocks voltage-gated sodium channels in mammalian excitable neuronal cells causing paralytic poisoning and, in the most severe cases, can lead to human fatalities due to respiratory and heart failure [1,2]
Following the initial findings of [3], TTX was detected in mussels and oysters from the Netherlands in 2015 [5], which made the Dutch authorities to issue an advice in 2016 and proposing to apply a zero tolerance for TTX in shellfish, meaning that bivalves would only enter the markets with non-detectable levels of TTX after analysis with analytical methods able to detect a concentration of 20 μg kg−1 or lower [6]
In 2017, the European Food Safety Authority (EFSA) stated a scientific opinion, following a request from the European Union, on the risk related to the presence of TTX and TTX analogues in marine bivalves and gastropods [7]

Summary

Introduction

Tetrodotoxin (TTX) is a potent neurotoxin that blocks voltage-gated sodium channels in mammalian excitable neuronal cells causing paralytic poisoning and, in the most severe cases, can lead to human fatalities due to respiratory and heart failure [1,2]. Following the initial findings of [3], TTX was detected in mussels and oysters from the Netherlands in 2015 [5], which made the Dutch authorities to issue an advice in 2016 and proposing to apply a zero tolerance for TTX in shellfish, meaning that bivalves would only enter the markets with non-detectable levels of TTX after analysis with analytical methods able to detect a concentration of 20 μg kg−1 or lower [6]. In 2017, the European Food Safety Authority (EFSA) stated a scientific opinion, following a request from the European Union, on the risk related to the presence of TTX and TTX analogues in marine bivalves and gastropods [7]. Kg−1 is not expected to result in adverse effects in humans and recommended EU Member States to obtain more data on TTX occurrence EFSA stated that a concentration lower than 44 μg TTX equiv. kg−1 is not expected to result in adverse effects in humans and recommended EU Member States to obtain more data on TTX occurrence

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