Food Toxicology Chapter 6

Naturally Occurring Toxicants as Aetiology Agents of Food Borne Diseases

• Definition: Natural toxins are toxic compounds produced by living organisms, not harmful to the organisms themselves but toxic to other creatures, including humans, when eaten.
• Sources:
  • Plants as a natural defense mechanism against predators, insects, or microorganisms.
  • Microscopic algae and plankton in oceans or lakes that produce toxins harmless to fish or shellfish but toxic to humans.
  • Fungi and plant toxins.

Mycotoxins

• Definition: Toxic compounds produced by fungi, including molds, that can contaminate food crops.
• Examples:
  • Aflatoxins produced by Aspergillus flavus and A. parasiticus.
  • Ochratoxins produced by Aspergillus ochraceus and Penicillium verrucosum.
• Found in:
  • Staple foods like corn, cereals, nuts, and seeds.
  • Can cause long-term exposure effects on the immune system, normal development, and cancer.

Ciguatera Fish Poisoning

• Caused by: Ciguatoxin produced by marine microalgae (Gambierdiscus toxicus).
• Found in: Reef fishes in the Pacific and northern Caribbean.
• Symptoms:
  • Numbness and tingling of the lips, tongue, and mouth.
  • Gastrointestinal disturbances, including vomiting and diarrhea.
  • Muscle weakness and paralysis.

Puffer Fish Poison - Tetrodotoxin

• Produced by: Puffer fish (Takifugu spp.).
• Found in: Liver, ovaries, eggs, and skin of puffer fish.
• Toxicity:
  • Can be fatal if ingested in large amounts.
  • Can cause numbness, tingling, and paralysis.

Neurotoxic Shellfish Poisoning (NSP)

• Caused by: Brevetoxins produced by marine dinoflagellate (Karenia brevis).
• Found in: Shellfish, including clams, mussels, and oysters.
• Symptoms:
  • Numbness and tingling in the mouth and legs.
  • Loss of coordination.
  • Diarrhea and vomiting.

Paralytic Shellfish Poisoning (PSP)

• Caused by: Saxitoxins produced by marine dinoflagellates (Alexandrium catenella).
• Found in: Shellfish, including mussels, clams, and scallops.
• Symptoms:
  • Gastrointestinal disturbances.
  • Numbness and tingling in the mouth and lips.
  • Muscle weakness and paralysis.

Diarrhetic Shellfish Poisoning (DSP)

• Caused by: Okadaic acid and dinophysistoxins produced by dinoflagellates (Dinophysis spp.).
• Found in: Shellfish, including mussels, clams, and scallops.
• Symptoms:
  • Diarrhea and abdominal cramps.
  • Nausea and vomiting.
  • Fever and headache.

Amnesic Shellfish Poisoning (ASP)

• Caused by: Domoic acid produced by marine diatom (Nitzschia spp.).
• Found in: Shellfish, including mussels, clams, and scallops.
• Symptoms:
  • Nausea and vomiting.
  • Diarrhea and abdominal cramps.
  • Memory loss and confusion.

Azaspiracid Shellfish Poisoning (AZP)

• Caused by: Azaspiracid and its analogues produced by marine dinoflagellates (Azadinium spp.).
• Found in: Shellfish, including mussels, clams, and scallops.
• Symptoms:
  • Gastrointestinal disturbances.
  • Nausea and vomiting.
  • Diarrhea and abdominal cramps.

Scombroid Food Poisoning (SFP)

• Caused by: Histamine produced by bacterial decomposition of fish.
• Found in: Spoiled fish, especially tuna, mackerel, and bonito.
• Symptoms:
  • Nausea and vomiting.
  • Diarrhea and abdominal cramps.
  • Headache and skin rash.

Mushroom Poisoning

• Caused by: Toxins produced by various mushroom species.
• Symptoms:
  • Nausea and vomiting.
  • Diarrhea and abdominal cramps.
  • Confusion, visual disturbances, and hallucinations.

Aflatoxins

• Definition: Toxic substances produced by Aspergillus flavus and A. parasiticus.

• Found in: Contaminated food crops, including nuts, cereals, and seeds.

• Effects:

  • Can cause liver damage and cancer.
  • Can be present in milk and milk products, including breast milk.### History of Animal Health Implications

• By the mid-20th century, improved methods of feed handling, production, and storage reduced the occurrence of disorders in farm animals.

• However, it wasn't until 1960 that the human health implications of these disorders began to be clearly recognized.

• In 1960, a disease dubbed "turkey-X disease" affected over 100,000 young turkeys in England, characterized by liver necrosis.

• Around the same time, an increasing mortality and liver tumors were observed in hatchery-raised trout in Oregon.

Aflatoxins

• Aflatoxins are potent carcinogens that can affect any organ or system, especially the liver and kidney.
• They cause liver cancer and have been linked to other cancers.
• AFB1 is carcinogenic to humans, and the hepatocarcinogenic potency of aflatoxins is significantly increased in the presence of hepatitis B virus (HBV) infection.
• Aflatoxins are mutagenic, genotoxic, and may cause birth defects in children.
• Acute intoxication with a high dose of aflatoxin can result in fulminant hepatic failure and rhabdomyolysis.
• Chronic exposure to aflatoxin can result in liver cirrhosis and ultimately lead to hepatocellular carcinoma, as well as gall bladder carcinoma.

Lectins

• Lectins are natural compounds found in legumes, beans, peas, and lentils, which can bind to and clump together red blood cells.
• Lectins interfere with nutrient absorption from the intestines.
• Many types of beans contain toxins called lectins, with kidney beans having the highest concentrations, especially red kidney beans.
• As few as 4 or 5 raw beans can cause severe stomachache, vomiting, and diarrhea.
• Lectins are destroyed when dried beans are soaked for at least 12 hours and then boiled vigorously for at least 10 minutes in water.

Phytohemagglutinin (Red Kidney Bean Poisoning)

• Phytohemagglutinin is a sugar-based protein (glycoprotein) that is the main cause of toxin in red kidney beans.
• Some of the highest concentrations of this glycoprotein have been found in red kidney beans.

Solanines and Chaconine

• Solanines and chaconine are natural toxins found in potatoes, tomatoes, and eggplants.
• They can accumulate to high levels in greened, stored, damaged potatoes, causing acute poisoning, including gastro-intestinal and neurological disturbances.
• Potatoes with a high concentration of solanine will taste bitter and can be harmful if eaten in large quantities.
• To reduce the production of solanines and chaconine, potatoes should be stored in a dark, cool, and dry place, and green or sprouting parts should not be eaten.

Key Facts

• Natural toxins can be formed in food as defense mechanisms of plants, through their infestation with toxin-producing mold, or through ingestion by animals of toxin-producing microorganisms.
• Natural toxins can cause a variety of adverse health effects, posing a serious health threat to both humans and livestock.
• Some of these toxins are extremely potent.
• Adverse health effects can be acute poisoning, ranging from allergic reactions to severe stomachache and diarrhea, and even death.
• Long-term health consequences include effects on the immune, reproductive, or nervous systems, and also cancer.