Biotoxin risk assessment report

Summary

Risk assessment of the Scottish monitoring programme for marine biotoxins in shellfish harvested from classified production areas — September 2022 (FSS/2020/042)

Authors:

Jackie Potts, Claus-Dieter Mayer, Graham Horgan (Biomathematics and Statistics Scotland)
Sarah Swan, Tom Brook, Keith Davidson (SAMS Enterprise)

The aim of this study was to assess the Scottish monitoring programme for biotoxins in shellfish from classified inshore production areas in Scotland. This programme, conducted by Food Standards Scotland (FSS), determines the prevalence in both farmed and wild bivalve molluscs of the following:

• paralytic shellfish toxin (PST) which is responsible for paralytic shellfish poisoning
• domoic acid (DA) which is responsible for amnesic shellfish poisoning (ASP)
• lipophilic toxins (LT), some of which are responsible for diarrhetic shellfish poisoning (DSP)

The current FSS monitoring programme consists of a combination of monthly, fortnightly and weekly monitoring of biotoxin concentrations in samples of shellfish from classified areas. For some of the areas, data on potentially biotoxin-producing phytoplankton are also collected regularly.

A multidisciplinary approach was applied in this study, including statistical modelling, knowledge of biotoxins and biotoxin-producing phytoplankton, as well as understanding of the industry and legislative requirements in this area.

The biotoxin patterns observed in shellfish across Scotland throughout the year were established using data collected over a twenty-year period from April 2001 to March 2021. Using this data the current FSS monitoring programme was assessed to evaluate the risk of a toxic event at a particular location going undetected. Based on this, modified schemes are suggested.

Using a combination of the findings from the risk assessment of the current biotoxin monitoring scheme, biotoxin prevalence estimated by the statistical modelling and the maximum biotoxin levels observed in the data, the researchers were able to propose revisions to monitoring frequencies. In general, the proposed frequencies for testing are specific to shellfish species, biotoxin, location and time of the year.

FSS will use findings from this study to inform a review of the current biotoxin monitoring scheme.