Aflatoxins and food safety in Uganda 

By Kamara Dainel

Aflatoxins are toxic substances produced by certain moulds (fungi) that grow on crops, particularly in warm, humid environments. These toxins pose a significant threat to human health, as they are carcinogenic, can cause liver damage, and are linked to a variety of other health issues. Aflatoxins are commonly found in foods such as groundnuts (peanuts), maize (corn), and other grains, nuts, and seeds.

While the presence of aflatoxins in food is a natural phenomenon, it is crucial to understand how they contaminate food, how to mitigate risks, and the role of food safety practices throughout the food supply chain.

What Are Aflatoxins?

Aflatoxins are produced by certain species of moulds, mainly Aspergillus flavus and Aspergillus Parasites, which can contaminate crops during growth, harvest, or storage. These moulds thrive under specific conditions, especially when the crops are exposed to heat, humidity, and poor storage practices. Aflatoxins are of particular concern due to their ability to cause serious health issues, including liver cancer, stunted growth in children, weakened immune systems, and, in extreme cases, death.

There are several types of aflatoxins, but the most dangerous are aflatoxins B1, B2, G1, and G2, with aflatoxin B1 being the most toxic and commonly found in contaminated food. Aflatoxins can persist even after food processing, so contamination is a major concern for both raw and processed foods.

Foods Most Likely to Contain Aflatoxins

Certain foods are more likely to contain aflatoxins due to the susceptibility of the crops to mould growth.

Groundnuts (Peanuts):- Groundnuts are highly susceptible to aflatoxin contamination, especially when grown in warm, humid climates. Peanuts are a major source of aflatoxins, particularly when the nuts are harvested too early or not properly dried before storage.

Maize (Corn):- Maize, another staple crop in many regions, is prone to aflatoxin contamination, particularly when stored in damp or poorly ventilated conditions.

Other Nuts and Seeds:- Apart from groundnuts, other nuts like almonds, cashews, and pistachios, as well as seeds like sunflower and sesame, can also be contaminated by aflatoxins under favourable conditions for mould growth.

Grains and Spices:- Grains like rice and wheat, as well as spices like chili powder and black pepper, are also susceptible to aflatoxin contamination, particularly in warm, moist environments.

Dried Fruits and Animal Feeds:- Dried fruits, especially those stored improperly, and animal feed made from contaminated crops can also harbor aflatoxins, potentially entering the food chain.

The Risk of Aflatoxins in Groundnuts

Groundnuts are particularly prone to aflatoxin contamination due to their growth and harvest conditions. The fungi Aspergillus species are most likely to grow on groundnuts when the crop is grown in regions with high humidity and temperature. This typically occurs when the nuts are still in the ground or shortly after harvest.

If the groundnuts are not dried properly or stored in damp conditions, the mould can flourish, producing aflatoxins that can spread throughout the batch. Aflatoxin contamination in groundnuts can severely affect the nutritional quality of the product and pose significant health risks to consumers.

Ensuring Food Safety During Harvest, Handling, and Storage

Proper food handling practices from the time of harvest through to storage and consumption are crucial for minimizing aflatoxin contamination. Here are key steps that can be taken to ensure food safety:

1. Timely Harvesting: Farmers should avoid harvesting crops during periods of high humidity and rain, as these conditions favour mould growth. Harvesting should be done when crops are fully mature and dry.

Use of Resistant Varieties: Some crop varieties are more resistant to aflatoxin-producing moulds. Using such resistant varieties can reduce the risk of contamination.

2. Post-Harvest Handling:– Proper Drying: After harvest, crops should be thoroughly dried to reduce moisture content. Groundnuts, for instance, should be dried in the sun for several days to lower the moisture content to safe levels (below 10% for peanuts). Wet or damp groundnuts are more likely to become contaminated.

Sorting and Cleaning: It is important to sort and remove damaged or mouldy nuts and grains before storage. Contaminated grains should be discarded, as they can contaminate healthy crops during storage.

3. Storage Practices: Dry, Well-Ventilated Storage: Storing crops in dry, cool, and well-ventilated environments is crucial to preventing mould growth. Moisture should be controlled in storage facilities to avoid the conditions that favour aflatoxin-producing moulds.

Use of Aflatoxin-Free Storage Containers: Using airtight or moisture-proof containers can help to keep crops safe from humidity, preventing the growth of fungi.

How Can Farmers Eliminate Aflatoxins?

Good Agricultural Practices: Implementing GAPs such as crop rotation, proper soil management, and irrigation techniques can help reduce the likelihood of aflatoxin contamination.

Use of Biological Controls: Research has shown that certain biological agents, such as non-toxic strains of fungi, can be used to combat the harmful moulds in the field, using these biological controls, farmers can reduce the incidence of aflatoxin-producing moulds.

Monitoring and Testing: Regular testing of crops for aflatoxins, especially in regions known for contamination, can help identify affected crops early. This allows farmers to take immediate corrective actions.

Education and Awareness: Farmers should be educated on the risks of aflatoxins and provided with the necessary tools and knowledge to implement effective handling practices.

A Call to Action

Nutritionists’ Role: Nutritionists should advocate for the importance of food safety, raise awareness about aflatoxin contamination, and encourage consumers to be mindful of the risks. They should also guide individuals on how to choose safer foods and avoid consuming contaminated products.

Policy Recommendations for Policymakers: Governments should implement and enforce strict regulations on aflatoxin levels in food products. Regular monitoring, testing, and certification of food products can help reduce public health risks. They should also provide subsidies or incentives to farmers who adopt safer agricultural practices and invest in aflatoxin-free technologies.

Therefore, As a nutritionist, I urge the public, policymakers, farmers, and consumers to recognize the serious health risks posed by aflatoxins, especially in crops like groundnuts. To safeguard our health, it’s vital to adopt good agricultural practices and proper harvesting, drying, and storage methods.

Policymakers must enforce stricter regulations and promote aflatoxin-free standards. Farmers should be educated and supported in using safer techniques to prevent contamination. Consumers must remain vigilant by choosing well-handled and tested foods. Together, we can reduce the impact of aflatoxins and protect public health for a safer, healthier future.

Kamara Daniel- Nutritionist – Bwindi Community Hospital