Shellfish Biotoxins

The Marine Institute carry out a biotoxin monitoring programme to ensure that shellfish are not placed on the market that may contain naturally occurring marine toxins.
Shellfish Biotoxins,Testing Oysters in Laboratory.

This involves testing of shellfish for regulated marine toxins and analysing seawater for the presence of toxin producing phytoplankton. The programme is designed to detect toxicity in shellfish growing areas before shellfish are harvested to prevent the placement of toxic shellfish on the market.

The Marine Institute are the National Reference Laboratory (NRL) for marine biotoxins and operate within the EU network of NRLs which is led by the European Union Reference Laboratory for Monitoring of Marine Biotoxins (EURLMB) which is based in Vigo Spain. The objective of the NRL is to facilitate a high level of expertise, knowledge and communication on the topic throughout Ireland.

The NRL also provides the scientific framework required to implement appropriate sampling and analytical monitoring programmes.

We provide scientific advice to the Food Safety Authority of Ireland (FSAI), Sea-Fisheries Protection Authority (SFPA) and industry on matters relating to shellfish toxicity and harmful algal blooms. Shellfish toxin analysis results and phytoplankton counts for shellfish production areas are published on the Harmful Algae Bloom Website HABS.

Three groups of toxins are regulated for under (EU) No 853/2004 and the monitoring of shellfish is necessary to comply with this regulation before they can be placed on the market:

1. Ammesic Shellfish Toxins (the AST toxins, Domoic acids)

2. Paralytic Shellfish Toxins (the PST toxin; Saxitoxin group)

3. Lipophilic Marine Toxins including;

  • Diarrheic shellfish toxins (the DST toxin okadaic acid and dinophysistoxins)
  • Azaspiracid Shellfish Toxins (AZT (the AZT toxins)
  • Yessotoxin (the YTX toxins)

Standard methods are used for the analysis of these regulated toxins and all methods are ISO17025 INAB accredited (Scope 130T).

Regulation EC No 853/2004 governs the total amount of marine biotoxins that may be present in shellfish for the protection of consumers. These are:

  • 800 microgram per kilogram of the algal toxins that cause paralysis (Paralytic Shellfish Poison - PSP).
  • 20 milligram per kilogram of domoic acids which cause amnesia (Amnesic Shellfish Poison - ASP).
  • 160 microgram okadaic acid equivalent per kilogram expressed as a sum of okadaic acid, dinophysis toxins.
  • 3.75 milligram yessotoxin equivalent per kilogram and
  • 160 microgram azaspiracid equivalent per kilogram expressed as the sum of azaspiracid-1, 2 and 3.

Toxicity can occur at any time during the year, and the periods of closure can vary considerably from year to year.