Using antimicrobial products, like sulfites, is increasingly becoming a global concern as producers of farm-raised seafood (like shrimp) resort to this to increase profits. This and the naturally occurring marine biotoxins are just some of the factors that lead to unsafe marine products.
Marine biotoxins are produced by harmful algal blooms (HAB) that are unpredictable and can occur worldwide. In addition to seafood and shellfish contamination, they can also cause human and wildlife mortality. Due to the high demand for shellfish across the world, and the fact that toxins cannot be destroyed by heat during cooking, it is vital to test if shellfish are free from it.
Histamine is a cause of allergic reaction in humans, histamine poisoning can have effects ranging from mild skin discomfort to nausea, vomiting, and diarrhea. Histamine is a product of bacterial degradation of susceptible fish species.
Sulfiting agents are used with shrimp, lobster, and related crustaceans to prevent melanosis (a.k.a. “blackspot”). While sulfiting agents are very beneficial to the seafood industry, some consumers are highly allergic to sulfite residues in food. For this reason, the US FDA regulations state that seafood containing sulfite residues of 10 ppm or more must be labeled as containing sulfites.
These are produced by certain kinds of microscopic algae (a type of phytoplankton) that are naturally present in marine waters, normally in safe numbers, but periodically increase to harmful levels during algal blooms. Here are the most common marine biotoxins according to FAO:
Paralytic shellfish poisoning (PSP) in humans is caused by ingestion of shellfish containing saxitoxins. These toxins are accumulated in shellfish feeding on toxin-producing algae more commonly known in the country as “red tide”. Symptoms of human PSP intoxication vary from a slight tingling or numbness to complete respiratory paralysis. In fatal cases, respiratory paralysis occurs within two (2) to twelve (12) hours of consumption of the PSP contaminated food.
In humans, it is caused by the ingestion of contaminated bivalves such as mussels, scallops, oysters or clams. The fat soluble okadaic acid and its derivatives accumulate in the fatty tissue of the bivalves. DSP symptoms are diarrhea, nausea, vomiting and abdominal pain starting 30 minutes to a few hours after ingestion and complete recovery within three (3) days.
It is also known as domoic acid poisoning (DAP). It was first recognized in 1987 in Prince Edward Island, Canada. At this time, ASP caused three deaths and 105 cases of acute human poisoning following the consumption of blue mussels. The symptoms included abdominal cramps, vomiting, disorientation, and memory loss (amnesia).