Experts working on guidance for toxins in mollusks have made several recommendations for further research.
The guidance is intended to support the development of sampling, analysis and management approaches for harvesting and production areas to determine the level of toxins in bivalve mollusks as part of complying with market requirements.
It also covers aspects such as classification, pre-harvest monitoring, management of production areas, and post-harvest batch testing.
Work on the guidance comes as the Singapore Food Agency (SFA) conducted a simulation exercise to test operational readiness in responding to potential harmful algae blooms at coastal fish farms. Exercise HYDRA involved SFA personnel, ST Logistics Pte and Prestige Ocean Pte, and a local fish farm.
Shellfish poisoning spotlight
Harmful algal blooms (HABs) occur naturally. Certain species produce toxins that can pose serious risks to human health through the consumption of contaminated seafood, especially bivalve mollusks. A variety of gastrointestinal and neurological illnesses such as paralytic shellfish poisoning, amnesic shellfish poisoning, diarrhoeic shellfish poisoning, neurotoxic shellfish poisoning, and azaspiracid shellfish poisoning have been reported.
An expert meeting on marine biotoxins and HAB monitoring was held in October in Italy to develop FAO-IOC-IAEA guidance on monitoring of algal toxins in bivalve mollusks. The agencies involved are the UN Food and Agriculture Organization (FAO), International Atomic Energy Agency (IAEA), and the Intergovernmental Oceanographic Commission of UNESCO (IOC).
The FAO and WHO published technical guidance related to growing area aspects of bivalve mollusk sanitation programs in 2018, which was updated in 2021. It focused on general requirements and microbiological hazards but did not include toxic HABs or toxins.
Experts at the latest meeting identified some data and research gaps and issued a series of recommendations.
Scientists said current toxicity equivalency factors are based on lethality in animal assays that may not reflect the mode of action in humans. They recommended further research to clarify the toxicodynamics and toxicokinetics of most algal toxin groups.
Experts said there are multiple examples of toxins not regulated in shellfish being found in mollusk samples. For some of these, there is evidence of potential human-health impacts. They recommended that the FAO and WHO conduct a risk assessment for tetrodotoxins in bivalve mollusks.
Scientists also raised concerns about long-term, repeated exposure to marine toxins and the limited availability of rapid tests for use by industry as part of risk management.
Listeria risk assessment
A full report on the second part of a publication covering the risk assessment of Listeria monocytogenes in food has been published.
The scope of the second Joint FAO/WHO Expert Meeting on Microbiological Risk Assessment (JEMRA) was to perform a risk assessment of Listeria in selected foods using the models developed in the first meeting.
In the first meeting, the group worked on formal models for the risk assessment of Listeria monocytogenes for lettuce, cantaloupe, frozen vegetables, and ready-to-eat fish. It was concluded that the models should be programmed, tested, and reviewed. During the second meeting, several models were evaluated to characterize the risk of listeriosis due to the consumption of diced ready-to-eat cantaloupe, frozen vegetables, and cold-smoked ready-to-eat fish. However, the model for lettuce was not ready for evaluation.
Experts said outputs from risk assessment models were consistent with their experiences. This means they were considered useful and fit-for-purpose. However, the dose-response model can be improved by considering other factors, such as underlying health conditions.
End-product sampling and microbiological testing on its own had little effect on reducing the risk. However, there is value in sampling and testing to verify that other control measures are effective. Another factor was the importance of environmental hygiene management.
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