Scottish authorities detect ‘red alert’ levels of shellfish toxins

August 08, 2018

Reports of shellfish toxins have been increasing in and around Scotland recently — in particular, the toxins that cause diarrhetic shellfish poisoning (DSP) and paralytic shellfish poisoning (PSP).

These reports have strong implications for the shellfish industry in the area. Harvesters are limited in where they operate, and much of the industry is increasing testing in order detect toxins in its product.

According to the most recent results from the biotoxin monitoring program of Food Standards Scotland (FSS), 77 instances have been noted where DSP is at a red alert level, meaning the toxin is above regulatory limits — and the associated harvesting site will be closed.

DSP was detected at an amber alert level — below regulatory limits, but still present — in 80 results. For PSP, this number was 41. In these situations, FSS guidelines say that shellfish toxin testing should be increased.

FSS monitors the waters in and around Scotland for the presence of a number of marine biotoxins. Marine algae produces toxins in water, which is then filtered by shellfish (including mussels, oysters, clams and cockles) which can lead to the shellfish becoming contaminated. These toxins, as their names suggest, can sicken human consumers to the point of hospitalization and death, in the worst cases.

In its monitoring program, FSS tracks two things: the levels of algae in water samples taken from harvesting areas and the presence of toxins in shellfish flesh. Using the results, FSS can determine when and where there’s an increased risk of contamination so that the industry can take measures to protect consumers. Because these toxins can’t be destroyed by heat during cooking, testing the shellfish before it reaches consumer plates is essential.

Regulatory limits for how much of a given toxin is a permissible in shellfish, as listed on the FSS website, are:

  • Paralytic shellfish poisoning: 800 µg/kg

  • Amnesic shellfish poisoning: 20 mg/kg

  • Diarrhetic shellfish poisoning: 160 µg/kg

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Category: Food Safety