Aflatoxin is a toxic carcinogen produced by certain fungi ( Aspergillus flavus and Aspergillus parasiticus ) growing on the ground, decomposing vegetation, hay, grains.. They are regularly found in unsaved basic commodities such as cassava, chili, corn, cotton seeds, millet, peanuts, rice, sesame seeds, sorghum, sunflower seeds, tree nuts, wheat, and various spices. When contaminated food is processed, aflatoxin enters a common food supply where they have been found in pet and human food, as well as in raw materials for livestock. Animals fed contaminated foods can pass aflatoxin transformation products into eggs, dairy products, and meat. For example, contaminated poultry feeds are suspected in the findings of a high percentage of samples of Aflatoxin contaminated chicken and eggs in Pakistan.
Children are severely affected by exposure to aflatoxin, which is associated with dwarf growth, delayed progression, liver damage, and liver cancer. The association between childhood stunting and aflatoxin exposure has been reported in several studies but can not be detected in its entirety. Furthermore, the causal relationship between childhood stunting and aflatoxin exposure has not been clearly demonstrated by epidemiological studies, even though the investigation is underway. Adults have a higher tolerance for exposure, but are also at risk. No animal species are immune. Aflatoxin is one of the best known carcinogenic substances. Upon entering the body, aflatoxin can be metabolized by the liver into an intermediate reactive epoxide or hydroxylated into a less harmful aflatoxin M 1 .
Aflatoxin is most commonly ingested. However, the most toxic type of aflatoxin, B 1 , can seep through the skin.
The level of action of the United States Food and Drug Administration (FDA) for aflatoxins present in food or feed is 20 to 300 ppb. The FDA has had an opportunity to declare the withdrawal of both human and pet foods as a precaution to prevent exposure.
The term "aflatoxin" comes from the name of one of the prints that it produces, Aspergillus flavus . It was created around 1960 after his discovery as a source of "Turkish X disease". Aflatoxins form one of the major groups of mycotoxins.
Video Aflatoxin
The main types and metabolites
At least 14 different aflatoxins are produced in nature. Aflatoxin B 1 is considered to be the most toxic and produced by both Aspergillus flavus and Aspergillus parasiticus . Aflatoxin M 1 is present in the fermented broth of Aspergillus parasiticus , but aflatoxin M 2 is also produced when the infected liver metabolizes aflatoxin B 1 and B 2 .
- Aflatoxin B 1 and B 2 , produced by Aspergillus flavus and A. parasiticus
- Aflatoxin G 1 and G 2 , produced by some Group II A. flavus and Aspergillus parasiticus
- Aflatoxin M 1 , aflatoxin metabolites B 1 in humans and animals (exposure in levels can come from breast milk)
- Aflatoxin M 2 , aflatoxin metabolites B 2 in cow's milk fed contaminated food
- Aflatoxicol
- Aflatoxin Q 1 (AFQ 1 ), the major metabolite of AFB 1 in in vitro the other higher vertebrates
Maps Aflatoxin
Conditions of contamination
Aflatoxin is produced by both Aspergillus flavus and Aspergillus parasiticus, which is a common form of fungus â € Å"kurusâ € which is widespread in nature. The presence of such molds does not necessarily indicate that harmful aflatoxin levels are present, but exhibit significant risks. Fungi can colonize and pollute food before harvest or during storage, especially after prolonged exposure to high humidity environments, or stress conditions such as drought.
Original habitat Aspergillus is on the ground, decaying vegetation, straw, and grains suffered microbiological damage, but attacked all types of organic substrate every time conditions were favorable for its growth. Favorable conditions include high water content (at least 7%) and high temperatures. Aflatoxin has been isolated from all major cereal plants, and from diverse sources such as peanut butter and marijuana. The principal commodities that are regularly contaminated with aflatoxins include cassava, chili, corn, cotton seeds, millet, peanuts, rice, sorghum, sunflower seeds, tree nuts, wheat, and various spices devoted to human or animal consumption. Aflatoxin transformation products are sometimes found in eggs, dairy products, and meat when animals are fed contaminated grains.
A study conducted in Kenya and Mali found that the main practice for drying and storage of maize was inadequate in minimizing exposure to aflatoxin.
Organic plants that are not treated with fungicides may be more susceptible to aflatoxin contamination.
Pathology
No animal species is immune to the acute toxic effects of aflatoxin. Adult humans have a high tolerance for exposure to aflatoxin and rarely suffer from acute aflatoxicosis, but children are severely affected, and their exposure can lead to stunted growth and delayed development, in addition to all the symptoms mentioned below.
Exposure to high levels of aflatoxin produces acute liver necrosis, which then occurs in cirrhosis or liver carcinoma. Acute liver failure is manifested by bleeding, edema, altered digestion, changes in nutrient absorption and/or metabolism, and mental and/or coma changes.
Chronic exposure increases the risk of developing liver and gall bladder cancer, because the aflatoxin metabolite can be intercalated into DNA and alkylating the base through the epoxide. This is thought to cause mutations in the p53 gene, a gene important in preventing the development of cell cycle when there is a DNA mutation, or indicating apoptosis (programmed cell death). These mutations seem to affect some base pair sites more than others, for example, the third base of the 249 codon of the p53 gene appears to be more susceptible to aflatoxin-mediated mutations from nearby bases.
Chronic, subclinical display does not cause dramatic symptoms such as acute aflatoxicosis.
The expression of aflatoxin-related disease is influenced by factors such as species, age, nutrition, sex, and possible exposure along with other toxins. The main target organ in mammals is the liver, so the main aflatoxicosis is liver disease. Conditions increase the likelihood of aflatoxicosis in humans including limited food availability, environmental conditions that support mold growth in foodstuffs, and a lack of regulatory systems for aflatoxin monitoring and control.
Common diets including vegetables containing fire, such as carrots, parsnips, celery, and parsley can reduce the carcinogenic effects of aflatoxins.
Aflatoxin B 1 may cause immune suppression, and its exposure is associated with an increase in viral load in HIV-positive individuals.
There is no specific antidote for aflatoxicosis. Symptomatic and supportive care tailored to the severity of liver disease may include intravenous fluids with dextrose, active vitamin K, vitamin B, and high-quality but limited protein diets with sufficient carbohydrate content.
Detection in humans
There are two main techniques most commonly used to detect aflatoxin levels in humans.
The first method is to measure AFB 1 -guanine adduct in the subject urine. The presence of this breakdown product shows exposure to aflatoxin B 1 during the past 24 hours. This technique only measures recent exposure. Because of the half-life of this metabolite, the measured AFB 1 -guanin level may vary from day to day, based on diet, it is not ideal for assessing long-term exposure.
Another technique that has been used is the measurement of additive levels of AFB 1 -albumin in blood serum. This approach provides a more integrated measure of exposure over several weeks or months.
Animal
In dogs, aflatoxin has the potential to cause liver disease. Low levels of aflatoxin exposure require continuous consumption for several weeks to months for signs of liver dysfunction to appear. Some articles have suggested the toxicity level in dog food is 100-300 ppb and requires continuous exposure or consumption for several weeks to months to develop aflatoxicosis. No information is available to show that the restored dog will later succumb to aflatoxin-induced disease.
Turkey is very susceptible to aflatoxicosis. Recent studies have revealed that this is due to the metaphorically efficient cytokrom P450 mediated from aflatoxin B 1 in turmeric heart and glutathione-S-transferase-mediated detoxification deficiency.
Several studies on pregnant hamsters exhibited a significant relationship between aflatoxin exposure B 1 (4 mg/kg, single dose) and the emergence of developmental anomalies in their offspring.
In 2005, Diamond Pet Foods found aflatoxin in products manufactured at their facility in Gaston, South Carolina. In 23 countries, Diamond voluntarily recalled 19 products formulated with corn and manufactured at the Gaston facility. Testing of more than 2,700 finished product samples performed by the laboratory confirms that only two date codes of two adult dog formulas with "Best By" dates on April 3, April 4, April 5, and April 11 have the potential to be toxic.
List of outbreaks
International sources of commercial peanut butter, cooking oil (eg olive oil, peanuts and sesame), and cosmetics have been identified to be contaminated with aflatoxin. In some instances, liquid-chromatographic mass spectrometry (LC-MS/MS), and other analytical methods, show a range of from 48% to 80% of selected product samples because they contain aflatoxin in detectable amounts. In many of these contaminated food products, aflatoxin exceeds the safe limits of the US Food and Drug Administration (FDA), or other regulatory bodies.
- 2003 Kenya: acute poisoning, 120 deaths confirmed.
- February-March 2013: Romania, Serbia, Croatia imported into Western Europe - 2013 aflatoxin contamination.
- February 2013: Iowa contamination.
- 2014 (in progress): Nepal and Bangladesh, neonatal exposure, found in umbilical cord blood.
See also
- The total synthesis of aflatoxin
- aflatoxin contamination 2013
- Mycotoxins in cattle feed
Note
External links
- List and detailed information about all Aspergillus mycotoxins
- Aflatoxin, ICRISAT
- Aspergillusflavus.org
- Pet Food Re-Calling
Source of the article : Wikipedia
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