Worldwide, approximately 25.7 million tons of groundnut are produced annually from about 21 million hectares of cropped land. Asia alone produces 17.9 million tons, 70% of global production. Africa produces another 20%. About 60% of Africa's production comes from Western Africa.

Groundnut plays an important role in the diets of rural populations, particularly children, because of its high contents of protein (21-30%), fat (41-52%), and carbohydrate (11-27%). It is also rich in calcium, potassium, phosphorus, magnesium and vitamin E. Protein meal, a by-product of oil extraction, is an important ingredient in livestock feed. Groundnut haulms are nutritious and widely used for feeding livestock.

Yields are low, averaging about 800 kg ha-1, less than one-third the potential yield of 3000 kg ha-1. This large gap between actual and potential yields is due to several factors, including non-availability of seed of improved varieties, poor soil fertility, inappropriate crop management practices, and pests and diseases.

The Aflatoxin problem

Groundnut is prone to infestation by two closely related species of fungi, Aspergillus flavus and Aspergillus parasiticus. A. flavus is the most common specie in Africa and Asia, while A. parasiticus is predominant in America. Both species belong to a highly toxic group of mycotoxins known as aflatoxins.

Aflatoxin contamination of groundnut is a major hazard to human and animal health and is one of the most important constraints to groundnut trade. It is considered to be an important cause of hepatocellular carcinoma, one of the most common cancers in developing tropical countries. Studies in the Ivory Coast, Mozambique, Sudan, Swaziland, China, and Korea have reported high frequency of liver cancer compared with Western countries. One factor is the presence of dangerous toxins - including Aflatoxin B1 produced by fungi such as A. flavus and A. parasiticus - in groundnut and groundnut-based foods.

Aflatoxin contamination is health risk for both human beings and livestock; livestock productivity declines when animals consume contaminated feed. As a result of these concerns, the European Union has banned the import of groundnut with aflatoxin B1 content above 6 µg kg-1. The World Food Organization categorises samples with over 30 µg kg-1 as unfit for human consumption. However, groundnut and groundnut products available in Africa can contain over 1000 µg kg-1. In Nigeria, scientists have found as much as 120-510 µg kg-1 of aflatoxin B1, B2, G1 and G2 in groundnut sold in the market. Strict quality regulations imposed by many developed countries have contributed to a severe decline in international groundnut trade; exports have fallen sharply in many developing countries, with correspondingly severe impacts on their economic development. Because of these strict export regulations, much attention has been given to the aflatoxin contamination and other quality issues in export groundnut, but very little on groundnut that is consumed in the country.

Aflatoxin-causing fungi can infect groundnut during the crop season and even after harvest. Pre-harvest infection by A. flavus and consequent aflatoxin contamination is more important in the semi-arid tropics, especially when drought occurs just before harvest. Drought-stressed plants lose moisture from pods and seeds; physiological activity is greatly reduced. Both factors increase susceptibility to fungal invasion. There is also evidence that damage to groundnut by soils pests increase aflatoxin contamination.

Post-harvest conditions are also important. Poor harvesting and storage conditions can lead to rapid development of the fungi and thus high production of the toxin. Studies in Africa have shown that storage conditions are usually inadequate. Groundnut is often stored in the pod, but insects can easily damage the pods and facilitate penetration by the fungi. Groundnut is also stored (as shelled seed) in poorly ventilated areas, which favor fungal development.

Groundnut is used in a variety of food products that are widely consumed, thus widening the health risks of aflatoxin contamination. Small-scale farmers face another kind of risk - clean seed is sold (the market will not accept damaged seed), while the remaining (which could include damaged and contaminated seed) is consumed by the family or incorporated into feed for their livestock.

Several national and international institutes including ICRISAT have carried out research on pre-harvest aflatoxin contamination, and control through genetic resistance as well as biological and cultural methods. While there are genotypic differences in susceptibility to fungal invasion and aflatoxin production, the general level of resistance in the germplasm and breeding lines is low. Recent studies at ICRISAT show that agronomic practices can reduce contamination.

Clearly, scientists, farmers, and development agencies must work together to find solutions to the problem. This web site aims to provide current information on aflatoxin research. We hope the site will be useful, and that it will promote debate on this vital issue.