Shellfish toxicity in UK waters: a threat to human health?

Abstract

The potential for poisoning of humans through their consumption of shellfish which have themselves consumed biotoxin producing marine phytoplankton exists in the UK. Toxins are bio-accumulated within the shellfish flesh allowing them to reach harmful concentrations. This threat is in most part mitigated by monitoring programmes that assess both the presence of potentially harmful phytoplankton and shellfish flesh toxicity. However, the medical profession in the UK remains relatively ignorant of the potential for biotoxin derived shellfish toxicity, preventing quantification of magnitude, frequency, and severity of health effects in the community or the medical significance of more recently discovered toxins. While the current causative species and their toxins are relatively well characterised there remains a lack of understanding of the factors governing the temporal and spatial appearance of harmful phytoplankton. Expansion of shellfish aquaculture is likely both worldwide and in the UK. Better understanding of how harmful phytoplankton interact with their environment to promote the sporadic harmful blooms that we observe is required to underpin risk assessments.

Figure 1

Alexandrium cell numbers and PSP toxicity in the blue mussel (Mytilus edulis) from the Orkney Islands during 1997.

Figure 2

Dinophysis cells numbers and DSP results (positive/negative bioassays) in the blue mussel (Mytilus edulis) from a sea loch on the west coast, Scotland during 2001.