Faro, Portugal, April 22, 2025 (Lusa) - A neurotoxin detected in sea whelks caught off the Algarve could cause human poisoning if the mollusc is not properly prepared before being ingested, a researcher from the University of the Algarve (UAlg) warned on Tuesday.
Sandra Lage was part of the team from UAlg's Centre for Marine Sciences (CCMAR) that analysed 25 whelks, caught between November 2021 and October 2022, and told Lusa that the results showed that 76% had levels of tetrodotoxin above the maximum limit considered safe for human consumption by the European Food Safety Agency.
The buzina is a whelk-shaped mollusc about the size of a palm that is usually used to make dishes such as feijoada, but its consumption can pose health risks if the neurotoxin is not properly eliminated through effective disinfecting before it is eaten, the researcher warned.
According to Sandra Lage, the study, which was the master's thesis of Maria Pais, the first author of the article published in the journal ‘Food Control’, 25 whelks were captured over a year of sampling and it was found that 76% contained the toxin in concentrations not considered safe for human consumption.
It's a neurotoxin that "only causes some gastrointestinal problems" in low doses, but in high concentrations, "and if it's an elderly person or a child, it can even lead to cardiorespiratory arrest or even death", she explained.
Present in puffer fish and well-known in Asian countries, where "there have been many reported cases of people dying" from its consumption, tetrodotoxin "is an emerging toxin" in Europe, which "is not currently regulated or monitored in the European Union, because it was only recently discovered" on European territory, she explained.
Asked about the causes of the contamination, Sandra Lage replied that the study also analysed starfish, a common food for these whelks, but only one of the 25 caught in the same locations showed the presence of the toxin.
"This toxin is known to be produced by bacteria. And we know that it didn't exist here in the past. But the vector that led to the contamination of the whelks is still being studied. We know that the starfish is a potential vector, but there may be other types of prey that this variety eats, because it's a carnivore, an opportunistic carnivore," she argued.
Sandra Lage emphasised that, in addition to the scientific work, there are public health reasons at stake and considered it important to alert the public to the presence of this neurotoxin, which "was found exclusively in the visceral part, in the intestine, stomach, bladder, but not in the muscle part".
"If it's handled well, it doesn't carry a risk, but if it's handled badly it can carry that risk," she said, noting that boiling or freezing the whelks doesn't eliminate the toxin and that consumption is only safe with effective and proper removal of the innards.
Finding the cause of the contamination of the whelks will now be the aim of a new study by this CCMAR team, which has already received funding for this purpose, the researcher pointed out, estimating that work could begin this year.
MHC/AYLS // AYLS
Lusa
