Aflatoxins

Primary reference(s)

WHO, 2018a. Mycotoxins. World Health Organization (WHO). Accessed 8 October 2020.

WHO, 2018b. Aflatoxins. Food Safety Digest. Ref. No. WHO/NHM/FOS/RAM/18.1. World Health Organization (WHO). Accessed 8 October 2020.

Additional scientific description

Aflatoxins are among the most poisonous of the mycotoxins and place communities as well as individuals at risk. Mycotoxins are toxic compounds that are naturally produced by certain types of mould (fungi). Moulds that can produce mycotoxins grow on many foodstuffs such as cereals, dried fruits, nuts and spices. Mould growth can occur either before harvest or after harvest, during storage, on/in the food itself often under warm, damp and humid conditions. Most mycotoxins are chemically stable and survive food processing (WHO, 2018a).

Several hundred different mycotoxins have been identified, but the most commonly observed mycotoxins that present a concern to human health and livestock include aflatoxins, ochratoxin A, patulin, fumonisins, zearalenone and nivalenol/deoxynivalenol. Mycotoxins appear in the food chain as a result of mould infection of crops both before and after harvest. Exposure to mycotoxins can happen either directly by eating infected food or indirectly from animals that are fed contaminated feed, especially from milk (WHO, 2018a).

Aflatoxins are produced by certain moulds (Aspergillus flavus and A. parasiticus) which grow in soil, decaying vegetation, hay, and grains and the crops that are frequently affected by Aspergillus spp. include cereals (corn, sorghum, wheat, rice), oilseeds (soybean, peanut, sunflower, cotton seeds), spices (chili peppers, black pepper, coriander, turmeric, ginger) and tree nuts (pistachio, almond, walnut, coconut, Brazil nut). Large doses of aflatoxins can lead to acute poisoning (aflatoxicosis) and can be life-threatening, usually through damage to the liver (WHO, 2018a). Aflatoxins have been classified as human carcinogens by the International Agency for Research on Cancer (IARC, 2002).

Metrics and numeric limits

The United Nations food standards body Codex Alimentarius Commission has set the maximum levels for aflatoxin in foods, including various nuts, grains, dried figs and milk (in the range 0.5–15 μg/kg; a microgram is one billionth of a kilogram) (WHO, 2018a).

Examples of drivers, outcomes and risk management

Large doses of aflatoxins lead to acute poisoning (aflatoxicosis) that can be life-threatening, usually through damage to the liver. Outbreaks of acute liver failure (jaundice, lethargy, nausea, death), identified as aflatoxicosis, have been observed in human populations since the 1960s (WHO, 2018b). Aflatoxins also pose a significant economic threat, causing an estimated 25% or more of the world’s food crops to be destroyed annually (WHO, 2018b).

The World Health Organization (WHO) in collaboration with the Food and Agriculture Organization of the United Nations (FAO), is responsible for assessing the risk to humans of mycotoxins – through contamination in food – and for recommending adequate protection. Risk assessments of mycotoxins in food done by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) are used by governments and by the Codex Alimentarius Commission to establish maximum levels in food or provide other risk management advice to control or prevent contamination. Codex standards are the international reference for national food supplies and for trade in food, so that people everywhere can be confident that the food they buy meets the agreed standards for safety and quality, no matter where it was produced (WHO, 2018b).

The outcome of such health risk assessments can either be a maximum tolerable intake (exposure) level, or other guidance to indicate the level of health concern (such as the Margin of Exposure), including advice on risk management measures to prevent and control contamination, and on the analytical methods and monitoring and control activities. Tolerable daily intakes are used by governments and international risk managers, such as the Codex Alimentarius Commission, to establish maximum levels for mycotoxins in food. The maximum levels for mycotoxins in food are very low due to their severe toxicity (WHO, 2018b).

Exposure to mycotoxins needs to be kept as low as possible to protect human health. Mycotoxins not only pose a risk to both human and animal health, but also affect food security and nutrition by reducing access to healthy food. The WHO encourages national authorities to monitor and ensure that levels of mycotoxins in foodstuff on their market are as low as possible and comply both with national and international maximum levels, conditions and legislation (WHO, 2018b).