Potential Threats Posed by Tetrodotoxins in UK Waters: Examination of Detection Methodology Used in Their Control

Abstract

Tetrodotoxin is a neurotoxin responsible for many human fatalities, most commonly following the consumption of pufferfish. Whilst the source of the toxin has not been conclusively proven, it is thought to be associated with various species of marine bacteria. Whilst the toxins are well studied in fish and gastropods, in recent years, there have been a number of reports of tetrodotoxin occurring in bivalve shellfish, including those harvested from the UK and other parts of Europe. This paper reviews evidence concerning the prevalence of tetrodotoxins in the UK together with methodologies currently available for testing. Biological, biomolecular and chemical methods are reviewed, including recommendations for further work. With the recent development of quantitative chromatographic methods for these and other hydrophilic toxins, as well as the commercial availability of rapid testing kits, there are a number of options available to ensure consumers are protected against this threat.

Detection of Tetrodotoxin Shellfish Poisoning (TSP) Toxins and Causative Factors in Bivalve Molluscs from the UK

“…Here, confirmation has been provided for the continued presence of TTX, along the south coast of England in particular, between 2014 and 2016 inclusive, confirming the results of the original study were not a one-off event. As such, this study highlights a continued risk to food consumers from TTXs, noting in particular that these toxins are resistant to degradation under food processing conditions such as cooking or freezing [ 19 ]. Overall, the majority of samples analysed contained total TTX concentrations below the 44 µg/kg EFSA guidance threshold [ 20 ].…”

Acute Oral Toxicity of Tetrodotoxin in Mice: Determination of Lethal Dose 50 (LD50) and No Observed Adverse Effect Level (NOAEL)

“…Even though most intoxicated people should fully recover usually within 24 h [13], it was also reported that death may occur in less than 30 min [18], indicating a rapid rate of absorption from the gastrointestinal tract. Although hundreds of TTX intoxication cases have been published [19] it is difficult to find a correlation between toxin concentration and poisoning symptoms due to the scarce oral toxicity data. TTX is unequivocally toxic to mammals.…”

New Invasive Nemertean Species (Cephalothrix Simula) in England with High Levels of Tetrodotoxin and a Microbiome Linked to Toxin Metabolism

“…TTX, along with a range of analogues together termed the tetrodotoxins (TTXs) is a low molecular weight, water soluble neurotoxin associated with neurotoxic marine poisonings [ 16 ] found in a wide range of marine phyla, including most famously the pufferfish, as well as gastropods, crustacean, octopus and echinoderms [ 15 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. In recent years it has been detected in bivalve molluscs such as mussels, oysters and clams from the UK [ 36 , 37 ] as well as other parts of Europe including Greece, the Netherlands and Spain [ 38 , 39 ] and also New Zealand [ 40 ].…”

“…Unlike other marine biotoxins, TTX is associated primarily in the literature with production by bacterial species [ 19 , 41 , 42 , 43 , 44 ], although the biosynthetic pathway for the toxin has not yet been elucidated [ 42 ] and reports proposing association with phytoplankton have also been published for example, [ 30 , 38 ]. Most notable is the co-existence of TTX with certain genera of bacteria, including Vibrio , Bacillus and Pseudomonas [ 35 , 36 , 42 , 43 , 44 ]. The relationship between TTX and Vibrio is especially important given the links between bacterial prevalence, toxin occurrence and climatic change [ 37 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ].…”