To ensure human safety, the EU and Codex have set marine biotoxin regulatory limits, see Table 1. These limits are defined in terms of toxic equivalency (TEQs), which provides the information about the mixture of toxins and their analogs within the same group. To obtain TEQs, the mass of each toxin found in the mixture is multiplied by its toxic equivalence factor. These individual calculations are then added together and finally reported as total toxicity-weighed mass.
Monitoring Programs
Historically, marine biotoxins were limited to geographic areas where specific algae and host organisms were found. The sources and locations of outbreaks in recent decades are illustrated in Table 2. Outbreaks are now occurring more frequently due to the movement of harmful algae to other areas by international seafood trading, increased consumption, and tourism. Prevention is the best way to manage the risk of potentially serious seafood poisoning. Thus, the major points of monitoring and management programs often include the following elements:
- Environmental observations of plankton, fish kills, and animal behaviors;
- Regular sampling of plankton, fish, and shellfish;
- Analysis of the samples of water and animals for presence and quantification of harmful algae and toxicity of shellfish;
- Evaluation of the results;
- Dissemination of information and implementation of regulatory action; and
- Action plan or mitigation measures.
Each country should develop its own monitoring program and identify one or several agencies from industry, fishermen, or private consultants to verify its effectiveness. Reliable monitoring programs protect public health, minimize product losses, and reduce the costs of clinical treatment and investigation.
Processing for Detoxification
Because the mechanisms of natural detoxification occur slowly in most shellfish, methods to quicken detoxification help to reduce seafood industry losses. Currently, there are two groups of detoxification techniques for shellfish:
- Using temperature, salinity stress, ozonation, transplantation, and other methods that accelerate the rate of detoxification; and
- Removing the toxic tissue and organ of shellfish.
Evisceration alone is not enough when the DA level is very high. The options of combining evisceration with thermal processing or freezing could be used in such cases. Today, the EU has approved procedures for bivalve detoxification for ASP, PSP, and DSP.
Dajsiripun is food specialist, Global Competence Support Center, at SGS Food Safety Services in Thailand. Reach her at +66 2-683-0541 ext 2423.
References Furnished Upon Request
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