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Seafood Choices: Balancing Benefits and Risks
centrations that can invoke allergic-type reactions in susceptible consumers of raw or cooked fish. Cooking does not diminish these toxins. The primary fish involved include tunas and mackerels from the Scombridae family of fish—thus the name—and related species mahi-mahi (Coryphaenahippurus), escolar (Lepidocybium flavobrunneum), and others. The common feature distinguishing these fish is a higher proportion of free amino acids, i.e., histidine, lysine, and ornithine, naturally occurring in the muscle tissue, which can be decarboxylated to histamine, cadaverine, and putrascine. This conversion is driven by temperatures that allow growth of certain bacteria to generate the decarboxylating enzymes. Although regulatory action levels for histamine content (<50 ppm) have been established to prevent illnesses, cadaverine and putrascine have the potential to cause illness even in the absence of histamine (FDA, 2001a). Inadequate cooling at the point of harvest is considered the primary problem, and subsequent abuse can increase the potential hazard. Temperature control from harvest until consumption is recommended by the FDA (2001a). In the United States, HACCP mandates thermal controls from harvest through processing; most illnesses which continue to appear involve recreational harvests and imports. The incidences of illness could increase as more supply of affected species is imported and the illegal sale of recreational fish is not addressed with pertinent enforcement.
Naturally occurring toxins that have been associated with illnesses resulting from the consumption of certain molluscan shellfish such as oysters, clams, and mussels harvested from locations with specific environmental conditions include:
Paralytic Shellfish Poisoning (PSP)
Neurotoxic Shellfish Poisoning (NSP)
Diarrhetic Shellfish Poisoning (DSP)
Amnesic Shellfish Poisoning (ASP)
The filter-feeding mollusks accumulate the toxins in their viscera from the waters harboring naturally occurring marine algae (phytoplankton) that produce the toxins. Occurrence has involved both domestic and imported marine mollusks from tropical and temperate waters, depending on the particular species of phytoplankton and water conditions. Recent international reports include a comprehensive assessment of the potential occurrences that warrant closer scrutiny of particular algal species in various locations (FAO/IOC/WHO, 2004).
Related illnesses are rare but poisoning from shellfish toxins can be severe and deadly. Cooking is not considered sufficient to control potential