Mycotoxin – Aflatoxins

 

Introduction

Mycotoxins are naturally synthesized poisonous chemicals by some fungi under certain conditions, and they are present in food, spice or drugs. They can adversely impact humans and animals after consumption, by ingestion, inhalation or direct contact with the skin surface. The detrimental effects include several damages to internal organs, deficiency of the immune system, cancer and impaired metabolic, nutritional, or endocrine functions. These toxic compounds also damage crops and agricultural plants, reducing their yields significantly, damaging healthy plants and producing toxins that impair the human body severely. One of the most prevalent ones, and best known for its lethal reputation is Aflatoxins.

Aflatoxins overview

Aflatoxins are carcinogens produced by some types of molds, primarily Aspergillus flavus and Aspergillus parasiticus. The fungi grow in soil, decaying vegetation and numerous staple foodstuffs and commodities, for example: hay, maize, wheat, rice. In other words, they can be found on almost any crops or food. Aflatoxins enter the general food supply when contaminated food is being processed or consumed, or passing from an animal into its milk and meat. Some major types of the toxin group are Aflatoxin B1 and B2, Aflatoxin G1 and G2 and Aflatoxin M1.

History

The term “aflatoxin” originated from the name of the species Aspergillus flavus, in which the first discovery of them was made. During the 1950s and 1960s in England, turkeys’ mortality increased significantly, and the phenomenon was identified as a new disease with unknown characteristics. Later in 1960, aflatoxin was recognized by scientists as a causative agent of the mysterious Turkey ‘X’ disease that resulted in excessive mortality in turkey poults. They make up one of the major groupings of mycotoxins.

Pathology

There hasn’t been an animal species that is found to be immune to the acute toxic effects of Aflatoxins. Albeit the high tolerance for exposure and the rarity of lethal cases in adult humans, children are susceptible to the chemicals, with symptoms of stunted growth as well as delayed development were reported. High-level exposure produces an acute necrosis (acute aflatoxicosis), which later causes cirrhosis (normal liver tissues are replaced with scar tissues and regenerative nodules) or carcinoma of the liver. Necrosis is a form of cell injury in which autolysis results in the premature death of cells in living tissues. Cellular death due to necrosis arises from the activation of various receptors, leading to the loss of cell membrane integrity and an uncontrolled release of products of cell death into the extracellular space, and this is a detrimental, or even fatal condition. Acute liver failure is made manifest by bleeding, edema, alteration in digestion, changes to the absorption and/or metabolism of nutrients, and mental changes and/or coma. 

Chronic subclinical exposure, on the other hand, has less dramatic symptoms than acute aflatoxicosis, but it is still a causative factor of the increase in risk of developing liver and gallbladder cancer. This is due to the likelihood that aflatoxin metabolites may intercalate into DNA and alkylate the bases through epoxide moiety, causing a mutation in p53 gene, which is vital in prevention of cell cycle progression due to DNA mutation or apoptosis (programmed cell death). 

Aflatoxin-related diseases have different expressions, which are influenced by age, nutrition, sex and the possibility of concurrent exposure to other toxins. In mammals, the toxins target livers, so this makes aflatoxicosis a hepatic disease.

Real life cases

In 2004, Kenya experienced one of the most severe outbreaks of aflatoxins, causing 125 deaths and more than 200 cases of illness. The incident was traced to maize and millet that had been stored unsuitably in a condition that promoted fungal growth. This has emphasized the vital need for better agricultural practices and storage facilities.

India underwent a major public health crisis due to an Aflatoxins outbreak in 1974. The contamination was present on maize and other grains, with several cases of death reported. Although the exact number of cases was unknown, it was enough to raise awareness of society for improvement of storage practices as well as the danger of aflatoxins. 

Method of controlling

Level 1: Prevention

Preventive methods such as biological controls on farming, hygienic storage and manufacturing practices should be applied in order to minimize the growth of fungi on agricultural products and food. Scientists should also carry out experiments so as to develop genetically modified crops that are resistant to Aflatoxins.

Level 2: Detection

Various analytical methods, such as high-performance liquid chromatography (HPLC), enzyme-linked immunosorbent assays (ELISA), and mass spectrometry, are used to indicate the presence and levels of aflatoxins available. Regular monitoring and surveillance are crucial to protect public health. 

Level 3: Detoxification

Products with the presence of Aflatoxins may undergo radiation and light treatments to clear out the fungi. Thermal and pressure methods are also very helpful in getting rid of the hazardous chemicals. People also use chemical agents to remove the fungi, canceling out the adverse effect of the toxins.

Conclusion

All in all, mycotoxins, specifically aflatoxins, are prevalent in daily life and cause severe issues to our lives and impact agriculture negatively. With many real life examples of outbreaks illustrated, society should be more aware of aflatoxins and its consequences, thus working together to deal with the problem.

Resources

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7999035/ 

https://en.wikipedia.org/wiki/Aflatoxin