Topic 2 Aflatoxins (AFs)

Aflatoxins (AFs) are amongst the most poisonous mycotoxins and are produced by Aspergillus flavus and Aspergillus parasiticus strains, which grow in soil, decaying vegetation, hay, and grains.

Aflatoxins are undetectable at eye view and their presence cannot be determined except by means of specialized tests. Nomenclature are based on the fluorescence property under UV light, aflatoxins may fluoresce blue (aflatoxin B) and green (aflatoxin G).

Marco Verch Professional Photographer

“Top view, assortment of cereals, nuts, grains and seeds” by wuestenigel is licensed under CC BY 2.0. To view a copy of this license, visit https://creativecommons.org/licenses/by/2.0/?ref=openverse

Large doses of aflatoxins can lead to acute liver poisoning (aflatoxicosis) and can be life threatening, some are also carcinogenic, mainly B1 form, considered the most dangerous for humans.

Aflatoxins have also been shown to be genotoxic, meaning they can damage DNA and cause cancer in animal species. There is also evidence that they can cause liver cancer in humans. Due to their structure, aflatoxins can bind to the DNA of liver cells. This results in mutations which contribute to the development of cancer. Aflatoxins are genotoxic and AFB1 can cause hepatocellular carcinomas (HCCs) in humans.

Shine emitted by aflatoxins under ultraviolet light at right. At left, the same fruit under natural light.

Large doses of aflatoxins can lead to acute liver poisoning (aflatoxicosis) and can be life threatening, some are also carcinogenic, mainly B1 form, considered the most dangerous for humans.

Aflatoxins have also been shown to be genotoxic, meaning they can damage DNA and cause cancer in animal species. There is also evidence that they can cause liver cancer in humans. Due to their structure, aflatoxins can bind to the DNA of liver cells. This results in mutations which contribute to the development of cancer. Aflatoxins are genotoxic and AFB1 can cause hepatocellular carcinomas (HCCs) in humans.

Moldy nectarines

Picture created and uploaded by Roger McLassus on 27 October 2006.Author: Unknown, licenced by CC-BY-SA-3.0

Mould growth and aflatoxin production are greatest in warm temperatures and high humidity, particularly in tropical and sub-tropical regions (Campden). Crops that are frequently affected by Aspergillus spp. include:

  • cereals (corn, sorghum, wheat and rice),
  • oilseeds (soybean, peanut, sunflower and cotton seeds),
  • spices (chili peppers, black pepper, coriander, turmeric and ginger)
  • tree nuts (pistachio, almond, walnut, coconut and Brazil nut).

However, aflatoxins have also been detected in milk and in dairy and meat products, indirectly due to animals fed aflatoxin-contaminated feed

Ochratoxin A commonly contaminates dry fruits

This is a 10 day time lapse movie of a grape cluster that has been infected with Botrytis cinerea (early appearing gray fungus on lower grapes), Aspergillus niger (later appearing dark black fungus on rear grapes), and Mucor sp. (white filamentous fungus in front). The images were taken at 15 minute intervals.