aflatoxin

Topics: Aflatoxin, Aspergillus, Fungus Pages: 6 (1888 words) Published: December 18, 2014
Naturally Occuring Hazards: Aflatoxin
Aflatoxin is a naturally occurring mycotoxin produced by three types of mold: Aspergillus flavus, Aspergillus parasiticus, and Asperilligus nomius (more rare). Aspergillus flavus is common and widespread in nature and is most often found when certain grains are grown under stressful conditions such as drought. The mold occurs in soil, decaying vegetation, hay, and grains undergoing microbiological deterioration and invades all types of organic substrates whenever and wherever the conditions are favorable for its growth. Favorable conditions include high moisture content and high temperature, though growth can occur at quite low moisture levels and a broad range of temperature (13-37 degrees Celcius). At least 13 different types of aflatoxin are produced in nature with aflatoxin B1 considered as the most toxic. While the presence of Aspergillus flavus does not always indicate harmful levels of aflatoxin it does mean that the potential for aflatoxin production is present.

Aflatoxin is probably the most well-known mycotoxin, besides trichothecene, and the most researched. This is because aflatoxins are very toxic and highly carcinogenic. How badly a person is affected by aflatoxin mycotoxins depends on things like the person's age, gender, level of exposure, duration of exposure, health, strength of their immune system, diet and environmental factors. There are two main ways people are usually exposed to aflatoxins. The first is when someone takes in a high amount of aflatoxins in a very short time. This can cause liver damage, liver cancer, mental impairment, abdominal pain, vomiting, convulsions, edema, hemorrhaging, disruption food digestion/absorption/metabolism, coma, and death. The liver is the principal organ affected, but high levels of aflatoxin have also been found in the lungs, kidneys, brains and hearts of individuals dying of acute aflatoxicosis. Acute necrosis and cirrhosis of the liver is typical, along with hemorrhaging and edema.  Ingestion of low levels over a long period has been implicated in primary liver cancer, chronic hepatitis, jaundice, cirrhosis and impaired nutrient conversion. Aflatoxins may also play a role in other conditions, such as Reye’s syndrome. The other way people suffer aflatoxin poisoning is by taking in small amounts of aflatoxins at a time, but over a long period. This might happen if a person's diet has a small amount of aflatoxins, for example. When this happens it can cause growth and development impairment or liver cancer due to DNA mutation caused by aflatoxins. Aflatoxicosis is not contagious and drugs and antibiotics do little to help, and again damages the liver more than any other organ. Aflatoxin mycotoxins also suppress the immune system. There are three main types of aflatoxin mycotoxins: Aflatoxins B: This group includes aflatoxin B1 and B2. Aflatoxin B1 is the most common aflatoxin, as well as the most toxic and carcinogenic. Other aflatoxins include: aflatoxins G - this group includes aflatoxin G1 and aflatoxin G2; aflatoxins M - this group includes aflatoxins M1 and M2. These aflatoxins are metabolic products which are found in the urine and milk produced by animals which have been given feed with aflatoxins in it. Whereas the B designation of aflatoxins B1 and B2 resulted from the exhibition of blue fluorescence under UV-light, while the G designation refers to the yellow-green fluorescence of the relevant structures under UV-light. In addition, two metabolic products, aflatoxin M1 and M2, that are of significance as direct contaminants of foods and feeds. These were first isolated from milk of lactating animals fed aflatoxin preparations.

Aspergillus molds grow mostly on crops, such as grains and nuts. Under the right conditions, Aspergillus often grows on grain before it is harvested. But it can also grow on harvested grain if the grain is stored damp. Aspergillus also grows on substances like soil,...


References: http://www.apsnet.org/edcenter/intropp/topics/Mycotoxins/Pages/Aflatoxins.aspx
http://www.icrisat.org/aflatoxin/aflatoxin.asp
http://www.mycotoxins.info/myco_info/science_moa.html
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