Toxins, Allergen Labels and Food Recalls

Biological Seafood Toxins: Histamine, Ciguatera, and Shellfish Poisoning

Biological toxins can be produced by plants, mushrooms, marine algae whose toxins accumulate in seafood, or bacteria on foods such as fish. A major operational challenge for food managers is that biological toxins cannot always be reliably detected by sight, smell, or taste. As a manager, you cannot depend on sensory inspections by your kitchen staff to determine if seafood is toxic. Furthermore, many seafood toxins and histamine remain hazardous after ordinary cooking, freezing, smoking, or curing. Because ordinary cooking and freezing do not eliminate histamine, ciguatoxin, or shellfish biotoxins, managers must buy seafood from approved sources and maintain temperature controls to prevent histamine formation; temperature control does not prevent ciguatera or shellfish biotoxins.

Histamine poisoning, also known as scombroid poisoning, occurs when specific finfish are subjected to time-temperature abuse. When finfish such as tuna, bonito, mackerel, mahi-mahi, and bluefish are left in unsafe temperatures, bacteria on the fish produce an enzyme that converts the naturally occurring amino acid histidine into toxic histamine. Cooking and freezing do not remove hazardous levels of histamine once they develop in the fish tissue. Guests experiencing histamine poisoning may develop symptoms including facial flushing, sweating, a peppery sensation in the mouth, headache, hives, and heart palpitations. To control this hazard, managers must verify that susceptible fresh finfish arrive at 41°F (5°C) or lower and remain under continuous temperature control. Packing fish in ice is one practical way to maintain that receiving temperature, but it is not a universal regulatory requirement.

Ciguatera fish poisoning originates in the marine environment when predatory reef fish consume smaller herbivorous fish that have fed on toxic marine algae. Fish commonly associated with ciguatoxin include barracuda, grouper, amberjack, and snapper. Once ingested, ciguatoxin bioaccumulates in the organs and flesh of predatory marine fish. This toxin cannot be inactivated by cooking or freezing. An individual afflicted with ciguatera poisoning often displays a classic hallmark symptom: the neurological reversal of hot and cold temperature sensations, where cold items feel burning hot to the touch. Because temperature and cooking provide no protection against ciguatoxin, managers must strictly control this risk by buying reef fish exclusively from approved, reputable suppliers.

Shellfish toxins are also produced by microscopic marine algae and accumulate in filter-feeding molluscan shellfish such as clams, mussels, oysters, and scallops. Illnesses caused by these marine biotoxins include paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP), and amnesic shellfish poisoning (ASP). Shellfish harvested from waters affected by toxin-producing algae can cause severe illness, and these hazards may occur even when no visible 'red tide' is present on the water's surface. Cooking and freezing do not eliminate shellfish toxins from contaminated molluscan shellfish. Managers must protect guests by purchasing all molluscan shellfish exclusively from approved, reputable suppliers who harvest strictly from approved waters subject to required monitoring.