Aflatoxin----Beware of toxic fungi in your food

                                         Aflatoxin----Beware of toxic fungi in your food

Walking through Nigerian market, one cannot miss the women winnowing, roasting, cooling and grinding groundnuts and simsim into a paste locally called odii.

This delicacy is as old as time. But did you know that by the time this paste comes to your table, it could be contaminated with aflatoxins?

Aflatoxins are highly- toxic, naturally occurring chemicals produced by fungi known as aspergillus flavus and are directly linked to liver cancer (hepatocellular carcinoma).  Aflatoxins mostly occur in oilseeds especially groundnuts, maize, soybean and cottonseeds.

However, they may also be detected in milk, cheese, eggs and meat products because animals eat aflatoxin-contaminated feeds.

“Exposure in Nigeria is high because we rely on some of these fungi-vulnerable foods as our staple food. Aflatoxin monitoring is generally weak, thus allowing retailers to sell contaminated products to unsuspecting consumers. Many retailers make groundnut paste from the small insect-infested nuts as healthy ones are usually sold off.

Aflatoxins appear as a brownish-grey fluffy mould.

FACTORS FACILITATING GROWTH

Aflatoxins occur during the entire chain of food production; that is, pre- harvest, harvest, storage and processing. They mainly develop as a result of insufficient drying. Presence of low moisture allows growth of the moulds.

“Women and children are the pillars of the food handling chain and these have the least access to recommended technology. More often than not, we have delayed harvesting and inadequate drying and poor storage, which exposes foods to fungi,” he says.

Poor handling of seeds and grain exposes them to damage, which makes them prone to mould invasion.

“Cracks and breaks in grains are caused mainly during harvesting and shelling. Under any circumstance, fungal growth is several times faster in damaged compared to intact kernels,” he explains.

As a developing country, challenges of proper food storage are still rife in Nigeria.  Many of the storage facilities such as granaries and sacks are improperly dried, which presents a good environment for the flourishing of moulds.

Studies conducted in 2000 in Nigeria established that 48 per cent of the groundnuts stored by farmers for up to seven months tested positive for aflatoxins.

“Storage structures commonly used by farmers in Nigeria are traditional and may not maintain an even, cool and dry internal atmosphere; they do not provide adequate protection from insects and rodents; are not easy to clean and above all, are not waterproof. All these conditions favor mould growth and aflatoxin production.
CONSEQUENCES

Prolonged exposure to aflatoxins by humans and animals leads to adverse effects including death. In a several studies high aflatoxin levels in food were linked to liver cancer in humans.

Furthermore, the Centres for Disease Control and Prevention (CDC) and World Health Organisation (WHO) estimate that approximately 40 per cent of liver cancers in the tropical and sub-tropical parts of the developing world are related to aflatoxin consumption. In sub-Saharan Africa alone, an estimated 26,000 people die annually of liver cancer associated with aflatoxin exposure.

“This is because the toxins are sent to the liver for detoxification and later the kidney for filtration. However, as they keep accumulating, the normal liver cells are altered and they start producing abnormal cells resulting into cancer,” 

These toxins are also linked to increased susceptibility to maternal anaemia, childhood stunting and abdominal pain. According to the management of aflatoxins in groundnuts study, they (aflatoxins) have been reported to reduce immunity in humans and animals. This is because they interfere with the activities of important cells that boost immunity in the body.

Besides the health risks, the report points to the fact that the poisons have direct economic effects resulting in loss of produce and market value. Additionally, there are indirect economic effects from loss of animals and increased costs of veterinary and human health care services.

“Presence of high levels of aflatoxins in groundnuts may make it unacceptable for marketing, causing financial loss to the farmer or retailer. It is estimated that Africa loses at least $670m annually due to requirements for European Union aflatoxin standards for all food exports,” the report partly reads.
 
PREVENTIVE APPROACHES

The 2010 report calls for timely harvesting and drying of produce; careful harvesting to avoid mechanical damage especially where hand hoes are used to harvest pods and avoid putting produce in direct contact with the soil when drying, as aflatoxin producing fungi flourish in soil.

Rather, it is advisable that one dries produce on clean material such as tarpaulins and papyrus mats.

“For post harvest storage, it is advisable that bags are not placed directly on the floor, insects and rodents are controlled and a well-ventilated and dry store is maintained.

Also do not mix old and new stock produce,” the report partly reads, adding that before shelling, one should separate immature and pest-infested pods from the lot. In processing, it is recommended that nuts are roasted at temperatures of 120 degrees Celsius onwards as aflatoxin-producing fungi can survive at 100 degrees Celsius. 

KEEP YOUR GRAINS SAFE.