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    Controlling Aflatoxins


    Healthy Groundnuts
    © International Trade Centre, International Trade Forum - Issue 1/2001 

    Aflatoxin contamination stops groundnuts from entering the major import markets more than any other factor. Importers are required by law to systematically test incoming shipments for the total amount of aflatoxins and reject those exceeding the permitted maximum levels. Exporters unaware of aflatoxin contamination issues, limits, regulations and standards risk costly rejections, claims, downgrading of shipments or the banning of the export origin.

    Parallel to measures for aflatoxin prevention and control, developing countries need to adopt reliable sampling and analysis procedures. Accredited national quality control laboratories with well-trained staff are needed to determine the levels of aflatoxin contamination throughout the cultivation, harvesting and post-harvesting stages, as well as certify the quality of export products at origin.

    Groundnut producers and exporters in developing countries are not always aware of the public health risks of aflatoxins, nor of related quality requirements and health regulations in importing countries.

    Aflatoxins could slip into the food chain and endanger public health through products such as edible groundnuts, sauces, snacks or even groundnut cake used for livestock feeding. Large-scale health disorders and liver diseases attributable to aflatoxin intake are reported in African countries producing and consuming groundnuts. The non-compliance to the maximum permitted levels of aflatoxins in each importing market results in costly rejection or downgrading of shipments, or in bans on trade with particular origins.

    What are aflatoxins? 

    Aflatoxins are cancer-causing chemicals produced by species of Aspergillus moulds that can develop on groundnuts. The spores of these moulds are present anywhere in the air or soil. They require specific temperature, moisture and nutrient substrates to germinate.

    Aflatoxin contamination of groundnuts can occur during its cultivation in the field, as well as during harvesting, post-harvesting, storage and processing.

    Addressing risks in groundnut farming 

    Contamination of groundnuts in the field is the result of adverse environmental conditions, such as inappropriate temperature (drought), precipitation, relative humidity and insect infestation during specific growing stages of the crop.

    Farmers have minimal control over some of these environmental factors. However, good agricultural practice, including crop rotation, irrigation, timed planting and harvesting and the use of pesticides, can control or reduce aflatoxin contamination of the groundnut crop. Appropriate pre-harvest and harvest management and good agricultural practices are the best methods for preventing or controlling aflatoxin contamination of groundnuts. Timely harvesting could reduce crop moisture to a point where the formation of the mould would not occur. Moreover, the minimum damage of shells during mechanized harvesting of the crop reduces significantly the mould contamination.

    Careful storage and processing needed 

    Should contamination occur or persist after these stages, health hazards associated with the toxins must be managed through post-harvesting procedures, during storage and processing.

    Inappropriate storage facilities (whether on farm, on manufacturing or on distribution premises) and/or improper packaging of products could result in mould contamination during storage. Strict control of storage facilities and conditions (including temperature, moisture, physical damage of the product through handling or pests) prevents or reduces mould growth. Appropriate packaging, good storage conditions and appropriate use of pesticides help minimize the contamination.

    When contaminated groundnuts have been identified at the processing facility, cleaning and separation may be the first envisaged control measures. Electronic sorting and hand-packing of damaged, immature or mould-infested pods can significantly reduce the contamination of groundnuts in shell. However, since the toxins can diffuse and seep into the kernels, other procedures, such as thermal inactivation, ammonisation or absorbent materials can be successfully employed.

    Regular laboratory checks 

    Because of the erratic diffusion of aflatoxin and the existence of highly contaminated spots in shipments, applying adequate random sampling techniques is critical for the groundnut trade. Other factors are also important: sound, well-conceived sampling procedures and methodologies to test specified lots of materials; suitably equipped, accredited quality control laboratories and well-trained staff. These measures will cut back the likelihood of expensive legal procedures and the downgrading or refusal of shipments by importers.

    Towards harmonized standards 

    The need for harmonized aflatoxin standards is great, to guarantee both protection of public health and promotion of fair trade in groundnut-based products. The regulatory limits and standards concerning the accepted limits of aflatoxins (and myco-toxins in general) in food and feed products vary from market to market, between maximum levels of 20ppb (part per billion) for total aflatoxins in the United States and Australia, and the low limit of 4ppb for total aflatoxins and 2ppb for B1 aflatoxin imposed by the European Union for edible groundnuts. Exporters need to be aware that each country's regulatory limits and standards for acceptable aflatoxin limits are laws, and their violation has direct legal consequences.

    Businesses urgently require internationally-harmonized regulatory standards and measures for mycotoxins. According to the Agreement on the Application of Sanitary and Phytosanitary Measures (SPS), maximum permitted levels of potential contaminants in food and feed should be fixed in conformity with international Codex standards, guidelines, or other recommendations which are deemed to be scientifically justified, necessary and non-discriminatory. Thus Codex standards on mycotoxin contamination being developed by the Joint FAO/WHO Expert Committee on Food Additives stand a good chance to be adopted worldwide.