Department of Cell and Molecular biology, Louisiana

(Link to the National Library of Medicine > Mycotoxins - PMC )

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The term "mycotoxin" was coined in 1962 following the deaths of c.100,000 turkeys due to exposure to Aspergillus flavus (an aflatoxin) in their food. This event highlighted to researchers the potential for illness in other animals/ humans due to exposure to mycotoxins and the period between 1962 and 1975 has been called the 'mycotoxin gold rush' due to the activity of research. Today c.300-400 compounds are recognised as mycotoxins. 

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Mycoses is the term for diseases caused by the growth of fungi on humans and animals, such as ring worm and thrush. Whereas Mycotoxicoses refers to diseases caused by exposure to mycotoxins (and other toxic fungi). Mycoses range from irritating (such as athletes foot) to life threatening (invasive aspergillosis). The fungi that causes mycoses can be divided into 2 categories - primary pathogens and opportunistic pathogens. Primary pathogens affect otherwise healthy individuals with normally functioning immune systems, whilst opportunistic pathogens produce illness by taking advantage of debilitated or immuno compromised hosts. The majority of human mycoses are caused by opportunistic fungi. The methods of pathogenesis for both primary and opportunistic are complex. Some infections remain localised, while others progress to systemic infection. For many mycoses, the ordinary portal of entry is through the lungs, but direct skin contact is also common. 

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Mycotoxicoses occurs through "posioning by natural means" and are therefore comparable to exposures to pesticides or heavy metals. The symptons of mycotoxicoses depend on the type of mycotoxin; the amount and duration of exposure; the age, health and sex of the indivudal; and many other poorly understood synergistic effects involving genetics, dietary status, and interactions with other toxins. The severity of mycotoxin poisoning can be compounded by factors such as vitamin deficiency, alcohol abuse and infectious diseases. Mycotoxicoses are more common in under developed nations, and mostly result from eating contaminated foods. Skin contact with mold infested surfaces or inhalation of spore-borne toxins are also common sources of exposure, such as a mouldy home or work place. 

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The number of people affected by mycoses and mycotoxicoses is unknown although the total number affected is expected to be less than the number affected by bacterial, protozoan, and viral diseases, but is still a major international health problem. One characteristic in both mycoses and mycotoxicoses is that neither is communicable from person to person. ​​

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While all mycotoxins are of fungal origin, not all toxins created by fungus are called mycotoxins. For example, fungal products that are mainly toxic to bacteria (e.g. Penicillin) are usually called antibiotics. Mushroom poisons can cause disease and even death in humans but are excluded from discussions of mycotoxicology. Molds (i.e. micro fungi) make mycotoxins, whereas mushrooms and other macroscopic fungi make mushroom poisons. The distinction between mycotoxin and mushroom poison is based not only on the size of the producing fungus but also on human intention. Mycotoxin exposure is almost always accidental. Mushroom poisons however are almost always accidentally ingested by mushroom hunters (or a very few unlucky people murdered by the poisons).

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Mycotoxins are not only hard to define, they are also hard to classify due to their diverse chemical structures and biosynthetic origins, their varied biological affects, and their production by a wide variety of fungal species. Classification schemes therefore tend to reflect the training of the person doing the categorising. Clinicians for example often classify them by the organ they affect (hepatoxins for the liver, nephrotoxins for kidneys, neurotoxins for the nervous system, immunotoxins for the immune system and so on). Cell biologists however put them into generic groups such as teratogens (causing malformation of an embryo), mutagens (causing genetic mutation), carcinogens (causing cancer) and allergens (causing an allergic reaction). Organic chemists have been classifying them by their chemical structures (e.g. lactones, coumarins etc.), biochemists according to their biosynthetic origins (polyketides, amino acid-derived, etc.); physicians by the illnesses they cause (e.g., St. Anthony's fire, stachybotryotoxicosis), and mycologists by the fungi that produce them (e.g., Aspergillus toxins, Penicillium toxins). Aflatoxin, for example, is a hepatotoxic, mutagenic, carcinogenic, difuran-containing, polyketide-derived Aspergillus toxin.

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Detailed toxins and health effects

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1. Aflatoxins

• Sources: Aspergillus flavus, Aspergillus parasiticus (found in contaminated grains, nuts, spices).

• Health Effects:

  • Acute toxicity: Severe liver damage, acute aflatoxicosis (often fatal).

  • Chronic toxicity:

    • Carcinogenicity: Linked to liver cancer (classified as Group 1 carcinogen by the IARC).

    • Hepatotoxicity: Chronic liver disease, cirrhosis.

    • Immunosuppression: Reduced resistance to infections.

    • Growth retardation in children.

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2. Ochratoxins

• Sources: Aspergillus ochraceus, Penicillium verrucosum (contaminates cereals, coffee, dried fruits, wine).

• Health Effects:

  • Nephrotoxicity: Kidney damage, chronic kidney disease (CKD).

  • Carcinogenicity: Potential renal cancer risk (Group 2B carcinogen).

  • Neurotoxicity: Cognitive impairment and nervous system damage.

  • Immunotoxicity: Suppression of immune function.

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3. Trichothecenes (e.g., Deoxynivalenol/DON, T-2 Toxin)

• Sources: Fusarium species (contaminates grains like wheat, corn, barley).

• Health Effects:

  • Gastrointestinal toxicity: Nausea, vomiting, diarrhea, anorexia.

  • Immunosuppression: Increased susceptibility to infections.

  • Neurotoxicity: Dizziness, headaches, fatigue.

  • Dermal toxicity: Skin irritation and blistering.

  • Reproductive toxicity: Impaired fetal development and fertility issues.

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4. Fumonisins

• Sources: Fusarium verticillioides, Fusarium proliferatum (found in corn and corn-based products).

• Health Effects:

  • Carcinogenicity: Linked to esophageal cancer (Group 2B carcinogen).

  • Neurotoxicity: Linked to neural tube defects in developing fetuses.

  • Hepatotoxicity and Nephrotoxicity: Liver and kidney damage.

  • Pulmonary toxicity: Respiratory issues in animals.

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5. Zearalenone

• Sources: Fusarium species (contaminates grains like corn, wheat, barley).

• Health Effects:

  • Endocrine disruption: Mimics estrogen, leading to hormonal imbalance.

  • Reproductive toxicity: Infertility, early puberty, and menstrual disorders.

  • Developmental toxicity: Effects on fetal development.

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6. Patulin

• Sources: Penicillium expansum (found in apples and apple products).

• Health Effects:

  • Gastrointestinal toxicity: Nausea, vomiting, and gastrointestinal distress.

  • Neurotoxicity: Possible nervous system effects.

  • Genotoxicity: Potential DNA damage.​​​