Fungal menace

The adverse effects of fungal toxins

Published: Friday 31 March 2000

THERE are several diseases that are associated with the consumption of mycotoxin contaminated food and feed. Mycotoxin, a toxic substance produced by fungi, can pass through the foodchain through a variety of plant products like cereals, corn, beans, rice and apples as also into animal products such as milk or meat. It is estimated that around 25 per cent of the world's agricultural produce is contaminated with mycotoxins. The illness caused by the consumption of these products is called secondary mycotoxicosis.

Mycotoxins elaborated by the species of Aspergilus, Penicillium, Fusarium and Alternaria are widely found in the foodchain, some of which do not get destroyed even at a temperature of 260C. These are capable of producing about three dozen toxins, depending on the situation, substrate and genetic makeup of the strain. Many other species like Pithomyces chartarum, Stachybotrys atra, Rhizoctonia leguminicola also produce metabolites that are harmful both to humans as well as to animals.

There are many instances of mycotoxicosis. In the early 1960s, an outbreak of mycotoxicosis among turkeys in the UK resulted in the death of nearly one hundred thousand birds. It was first named turkey X-disease, but several scientific studies later pointed out that it was due to fungal toxicosis. In 1974, a number of people died after consuming mouldy maize in Gujarat and Rajasthan. Investigations revealed that it was due to a fungus called Aspergillus flavus. Though food poisoning through mycotoxins is a worldwide problem, the risk is greater in the tropics than in the temperate zones.

The effect of fungal toxins in farm and laboratory animals suggest that it can affect vital organs such as liver, kidney, lungs and heart. Aflatoxin B, an important mycotoxin, is suspected to cause liver cancer in human beings. Different layers of skin also manifest many deformities and develop abnormal structures while the blood composition can change in some cases. Mycotoxins can also have adverse effect in plants. They can restrict seed germination and seedling formation as in some cases can also damage the chloroplast in many plants. The unscientific storage systems, especially among the poor people in tropical countries, provide a free entry to mycotoxin-producing fungi in their food commodities. Once these toxins are produced, it is very difficult to eliminate them from the food.

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