a fla toxins in human

8/2/2019 A Fla Toxins in Human

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AFLATOXICOSIS IN HUMAN

Presented

by

Hafiz Iftikhar Hussain2005-ag-1068


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Introduction

Aflatoxins are one of the most potent toxicsubstances that occur naturally. These are agroup of closely related mycotoxins produced byfungi Aspergillus flavusand A. parasiticus.

Aflatoxicosis is poisoning that result fromingestion of aflatoxins in contaminated food orfeed.

Aflatoxin poisoning is reported from all parts of

world in almost all domestic and non domesticanimals like cattle, horses, rabbits, and othernon human primates.

Aflatoxicoses is also reported in humans in

many parts of the world.


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Exposure to Aflatoxin

Diet is the major way through which humans aswell as animals are exposed to aflatoxins.

Apart from this, exposure to aflatoxin can be

through ingestion of contaminated milkcontaining Aflatoxin M1(metabolite of AFB1).

Occupational exposure to aflatoxins inagricultural workers, people working in oil mills,and granaries have been reported.


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Aflatoxin carcinogenicity

After wide experimentation on many animalspecies like rats, aflatoxin especially aflatoxin B1is confirmed as a potential carcinogen (IARC1993). Metabolism plays a major role in deciding

the degree of toxicity. After ingestion, aflatoxin is metabolized by

cytochrome p450 group of enzymes in the liver,where it is converted to many metabolic

products like aflatoxicol, aflatoxin Q1, aflatoxinP1, and aflatoxin M1, depending on the geneticpredisposition of the species.

Along with the above another metabolite called

aflatoxin 8,9 epoxide is also formed.


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The amount of this metabolite decides the

species susceptibility as this can inducemutations by intercalating in to DNA ,by formingan adduct with guanine moiety in the DNA.

In correlation with the decrease in liver function,

there is a derangement of the blood clottingmechanism, icterus (jaundice), and a decreasein essential serum proteins synthesized by theliver.

Other general signs of Aflatoxicosis are edemaof the lower extremities, abdominal pain, andvomiting.


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Chronic Toxicity

This is due to long term exposure of moderate tolow aflatoxin concentration. The symptomsinclude decrease in growth rate, lowered milk or

egg production, and immuno suppression. There is some observed carcinogenecity, mainly

related to aflatoxin B1.

Liver damage is apparent due to the yellow colorthat is characteristic of jaundice, and the gallbladder becomes swollen.


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Immuno-suppression is due to the reactivity ofaflatoxins with T-cells, decrease in Vitamin K

activities, and a decrease in phagocytic activityin macrophages.

These immuno suppressive effects of aflatoxins

predispose the animals and humans to manysecondary infections due to other fungi, bacteriaand viruses.


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Aflatoxin and Hepatitis

Many experiments conducted in different areasespecially in China and in the African countries,have shown high incidence of hepatitis B virus

infection where dietary exposure to aflatoxinswas prevalent.

Subsequent research proved that both aflatoxinsand hepatitis B virus act synergistically in the

etiology of liver cancer.


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Aflatoxin and children Foetal and childhood environment, including the

nutritional status of the pregnant mother and theinfant, are considered critical for growth and riskof disease in earlier life.

Malnourishment is one of the common problems

in developing countries. Apart from these, theyare also exposed to high levels of mycotoxins.Aflatoxins are the major among these.

It has been proved that these aflatoxins are

immunogenic, teratogenic, and they retard thegrowth among experimental animals. In thedeveloping countries like India and China, theenvironmental conditions favor their production.


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A study in West Africa showed a significantcorrelation among the aflatoxin exposure andstunted growth in children who are exposed toaflatoxin right for neonatal stages.

Apart from that due to the capacity of aflatoxinsto cross the placental barrier, can cause geneticdefects at foetal stages itself.


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Treatment of Aflatoxicosis

Detoxification A variety of detoxification methods for human food

and animal feed have been reported.1. Physical methods (bentonite, sodium hydroxide

calcium aluminum adsorbents and clay)2. Chemical methods (5% NaOCl, 10% of chlorine gas,ammonia, and solvent extraction)

3. Phytochemicals (isothiosinates, flavonoids, allicin,and chlorophyllin), and biological methods

(Flavobacterium aurantiacum).


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Aflatoxin absorption properties are more inlactic acid bacteria, used as a method of

detoxification is best suited for food and dairyproducts.

The method depends on the type of lacticbacteria, in which the bioavailability varies

depending on the type of aflatoxin. Avoidance of food containing aflatoxins is the

primary measure. Once exposed, there is a riskof future cancer, there is no treatment to prevent

this. For an acute exposure, amphotericin B and

itraconazole may be helpful.


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References

Amercin Journaj of Clinic Nutrition, Vol. 80 No.5, 1106-1122, Nov. 2004.

Handbook of Applied Mycology (Handbook ofApplied Mycology, Vol. 5). Arora

A paper onIMPORTANCE OF AFLATOXINS IN HUMANAND LIVESTOCK HEALTH by A.S.

Bommaknati, and F. Waliyar. Eaton L Dave. 1997. Aflatoxin toxicology

Chapter 9.26 Comprehensive Toxicology,Pergamon publications 1997.


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a fla toxins in human

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