Aflatoxin Mycotoxins
Aflatoxins are a type of mycotoxin produced by some species of the Aspergillus toxic molds. Along with Trichothecenes, Aflatoxins are the most well known mycotoxins and probably the most researched. Aflatoxins are of such interest because they are highly toxic and are one of the most carcinogenic substances in the world.
Aflatoxin Types
Aflatoxin mycotoxins are classified into three main groups:
- Aflatoxins B: includes Aflatoxin B1, the most predominant as well as the most toxic and carcinogenic aflatoxin, and Aflatoxin B2.
- Aflatoxins G: includes Aflatoxin G1 and Aflatoxin G2
- Aflatoxins M: includes Aflatoxins M1 and M2, metabolic products found in the urine and milk produced from animals (such as cows) which have been given feed with aflatoxins in it.
Aflatoxin Toxicity
Humans and all animals are susceptible to the toxic and carcinogenic effects of Aflatoxin mycotoxins. Tests have shown that the LD50 (the dosage level that caused 50% of the group to die) rate for animals is generally between 0.5 and 10 mg/kg of the animal's weight. Compared to most animals, humans are relatively tolerant to the effects of Aflatoxins however.
Aflatoxin Symptoms
A person's susceptibility to Aflatoxin mycotoxins depends on factors such as age, gender, level of exposure, duration of exposure, health, strength of immune system, diet and environmental factors.
Aflatoxicosis refers to poisoning from Aflatoxin mycotoxins. It usually occurs from ingestion of foods contaminated with Aflatoxin mycotoxins. Aflatoxicosis is not contageous and drugs and antibiotics do little to help. The liver is the organ primarily damaged by Aflatoxicosis. Aflatoxins also suppress the immune system.
Aflatoxin exposure in humans is usually either due to a high concentration in a short period of time such as when someone eats foods badly contaminated with aflatoxin mycotoxins, or exposure in low concentrations over a long period of time such as when a person's diet contains small amounts of aflatoxins.
Symptoms of high concentration Aflatoxin exposure can include:
- Liver damage
- Liver cancer
- Mental impairment
- Abdominal Pain
- Vomitting
- Convulsions
- Edema
- Pulmonary Edema
- Hemorrhaging
- Disruption of food digestion, absorption or metabolism
- Coma
- Death
Symptoms of chronic exposure to low concentrations of Aflatoxin:
- Growth and development impairment
- Liver cancer due to DNA mutation caused by Aflatoxins
Aspergillus & Aflatoxin Production
Aflatoxin mycotoxins are produced by Aspergillus which grows mostly on crops such as grains and nuts. Aspergillus often can grow on grain before it is harvested, under the right environmental conditions, or after harvesting if it is stored while damp. The conditions which are most suitable for Aspergillus to grow on organic materials are high moisture levels of the material (7% or more) and warmth. Aspergillus will generally grow in substances such as grain, soil, hay, grain and vegetation that is decaying.
Aflatoxin in Food
According to an esimate by the American Food and Agriculture Organization, 25% of the food crops in the world are affected by mycotoxins with Aflatoxin mycotoxins being the most problematic.
The crops most at risk of being contaminated by Aflatoxins are corn, cottonseed and peanuts. Aspergillus also commonly grows on beans, rice, tree nuts and wheat, and to a lesser extent other grains and nuts.
Aflatoxins can also appear in milk, eggs and meat from animals that have been given feed contaminated with aflatoxin mycotoxins. Aflatoxin M1 and M, which are often found in cow's milk, are metabolites produced by animals which have consumed Aflatoxins.
Aflatoxin Levels in Food
Although Aflatoxins are found all over the world they are much less of a problem in developed nations than they are in undeveloped or developing nations. In developed countries high levels of Aflatoxin mycotoxins in foods are prohibited. The USA limits the level to below 20 parts per billion in food and specifies that the Aflatoxins M must be under 0.5 parts per billion in milk.
To minimize the levels of mycotoxins, chemical methods are used in foods such as nuts, corn, grains and milk to remove Aflatoxins. Although usually well below the safety limits, most foods, such as peanut butter, will still contain very small amounts of Aflatoxins which has generated concern about the effects on humans of long term ingestion of low levels of Aflatoxins.
It is believed the carcinogenic effects of Aflatoxins can be reduced through eating vegetables such as carrots and celery.
Aflatoxin in Pet Food
Deaths of pets from eating pet foods contaminated with Aflatoxin mycotoxins does occur in developed countries. In late 2005 to early 2006, 23 or more dogs died from eating Diamond Pet Foods dog food which was contaminated with Aflatoxins.