The Marine Institute is responsible for monitoring the presence of naturally occurring phytoplankton toxins in Irish shellfish and the analysis of seawater for the presence of toxin producing phytoplankton. The programme is designed to detect toxicity in shellfish growing areas before harvesting, thereby providing the necessary information to restrict the placing of toxic shellfish on the market. The laboratory has the most comprehensive dataset on toxic phytoplankton and phycotoxins in Ireland having set up the programme in 1984.
Shellfish toxins are detected in compliance with EU Directives using a both chemical and bioassay methods. Bioassays are a broad spectrum test that are widely used in Europe as the primary method of detecting such toxins. If toxins are detected at levels which are unsafe for human consumption, the harvesting and sale of shellfish from the production area is prohibited. The ban on harvesting and sale of shellfish is lifted only after thorough scientific analysis of samples show that the product is safe for human consumption over two consecutive tests.
Toxicity can occur at any time during the year and the periods of closure can vary considerably from year-to-year. The main toxicity that affects Irish shellfish are from a group of phytoplankton called the dinoflagellates. While most of these are beneficial, a small number of species produce toxins, usually in the summer, although we have had winter episodes from both known and unknown sources.
The complex toxin profile of Irish shellfish necessitates year round vigilance on the part of the industry and monitoring agencies, and regular testing should be integrated into the producers routine quality control procedures.
Proceedings from the past 5 Irish Shellfish Safety Scientific Workshops are now available to download in our Publications and Data Section under Marine Environment & Health Series section (.pdf format).
For Further information contact
Joe Silke