1.1 What are aflatoxins?

Many agricultural commodities are susceptible to several diseases caused by fungi, viruses and insect pests. These diseases may also contaminate the crops with deadly toxins. Fungi are of particular concern. Fungi are free-living organisms capable of surviving in the environment (soil, air and water) and can easily find their way into crop products especially when the weather conditions are suitable. Many of these fungi are free-living organisms and can survive in the environment even without the crops we grow. The toxins produced by fungi are called mycotoxins (myco=fungus; toxin=poison). Approximately 25% of the world’s agricultural commodities are contaminated by aflatoxin and other mycotoxins, resulting in nearly one billion tons of food loss every year1. Although there are multiple types of mycotoxins, aflatoxins are of particular concern because of how their high toxicity affects human health and the significant economic losses associated with contaminated staple crops.

1.2 Effects of aflatoxins

Food products that are commonly contaminated by aflatoxins include cereals (maize, sorghum, pearl millet, rice and wheat), oilseeds (groundnut, soybean and sunflower), spices (chillies, black pepper, coriander, turmeric and ginger) and milk from cattle that have eaten contaminated feeds. Aflatoxin cannot be destroyed by cooking. Aflatoxin contamination of food products have two major effects. Firstly, eating contaminated food has several harmful health effects and secondly, aflatoxin contamination affects the quality of the grain which leads to reduced markets for contaminated grains.

Health effects: Eating food contaminated with aflatoxins leads to aflatoxin poisoning also called aflatoxicosis. Regular consumption of low dosages for a long time (Chronic exposure) leads to liver damage, immune suppression, malnutrition and stunted growth in children, while sudden high-level ingestion of the toxin (Acute exposure) can lead to death.

Income losses: Groundnut, maize and other crop products are important as a source of income when sold locally or exported. To protect humans from the harmful effects of mycotoxins, especially aflatoxin, the European Commission has proposed maximum allowable limits for aflatoxin in certain foods. The permissible limit of aflatoxin in foods for human consumption is 4-30 ppb, depending on the country involved (FDA 2004; Henry et al. 1999). In the United States, 20 ppb is the maximum aflatoxin residue limit allowed in food for human consumption (FAO 2003). Due to aflatoxin contamination the food products cannot be exported leading to financial losses. For example Malawi lost as much as 42% of its groundnut exports in 2005 (Diaz-Rios and Jaffe 2008).