Aflatoxins

The group of aflatoxins mainly consist of aflatoxin B1; B2; G1; G2 and M1. Aflatoxins are produced by strains of Aspergillus, particularly A. flavus and A. parasiticus. Production of aflatoxins is greater during hot and humid conditions (optimally with day temperatures around 32°C and night temperatures around 24°C).5, 7, 9 Aflatoxins are often a storage issue though contamination of food and feed material can also occur in the field e.g. on crop parts damaged by pests or drought stress. Inadequately dried material or high humidity contribute to the production of aflatoxins in storage.5, 7, 8

The fungus spreads by spores (microconidia) through the action of rain splash, wind and insects. Spores germinate and the fungus can penetrate plant material often facilitated by pest or other damage.5 Grains that are stored at high moisture content (e.g. >14%), high temperature (>20°C) and present damages can potentially be contaminated.5 Because individual damaged grains can be very high in aflatoxins, there can be a highly heterogeneous distribution of aflatoxins and sampling needs to be very careful to avoid missing a contamination problem.

Aflatoxins are very stable compounds and resist several food processing techniques like roasting, extrusion, baking and cooking, hence they represent a severe risk for humans and animals.2, 7, 8, 9

Toxicity

Aflatoxin B1 is considered the most toxic aflatoxin. This mycotoxin is metabolized in the liver, where it forms secondary toxic metabolites like the hydroxylated form aflatoxin M1.3, 4, 5, 7 This mycotoxin is excreted in the urine and in the milk. Studies showed that aflatoxin M1 can already be detected in milk after 12-24 hours after exposure.5, 7 However, a consistent aflatoxin M1 presence in milk occurs after 3-6 days of continuous consumption of aflatoxin B1 contaminated feed.2, 5, 7

Aflatoxins are potent carcinogens for human and all animal species investigated. These mycotoxins were included in the group 1 (substances that are highly carcinogenic for humans) by the IARC in 2002.2, 7 Aflatoxins are the only mycotoxins that are strictly regulated in markets like the EU and USA (tables 1 and 2).2, 3, 4 Aflatoxins are genotoxic compounds and target several organs like liver, kidneys, reproductive and immune systems.5, 7, 8, 9 Symptoms include: vomiting; necrosis; anorexia; fatty liver; liver cancer and diarrhea. Effects on the reproductive system include: delayed testicular development and morphological changes; decline in the percentage of live sperm and reduced plasma concentration of testosterone.5, 7, 8, 9 Immunosuppressive effects include marked decreased resistance to secondary infections by fungi, bacteria and parasites. Other aflatoxin related symptoms are: encephalopathy with fatty degeneration of viscera and pulmonary interstitial fibrosis.5, 7, 8, 9

European Union

Table 1. Regulation for aflatoxins in animal feed in the EU.3, 4
European Union
CommodityProducts intended for animal feedMax. content in mg/kg relative to a feed with a moisture content of 12%
Feed materials0.02
Complementary and complete feed with the exception ofCompound feed for dairy cattle and calves, dairy sheep and lambs, dairy goats and kids, piglets and young poultry animals0.005
Compound feed for cattle (except dairy cattle and calves), sheep (except dairy sheep and lambs)0.02

USA

Table 2. Regulation for aflatoxins in animal feed in the USA.4
USA
CommodityAction levels (mg/kg)
Corn and peanut products intended for fishing (i.e. feedlot), beef cattle0.3
Cottonseed meal intended for beef, cattle, swine, or poultry (regardless of age or breeding status)0.3
Corn and peanut products intended for finishing swine of 100 pounds or greater0.2
Corn and peanut products intended for breeding beef cattle, breading swine or mature poultry0.1
Corn, peanut products, and other animal feeds and feed ingredients but excluding cottonseed meal, intended for immature animals0.02
Corn, peanut products, cottonseed meal, and other animal feed ingredients intended for dairy animals, for animal species or uses not specified above, or when the intended use is not known0.02

European Union and USA

Table 3. Regulation for aflatoxin M1 in milk in the UE and USA.3, 4
European Union and USA
MarketsFoodstuffsMax value (µg/kg)
European UnionRaw milk, heath-treated milk and milk for the manufacture of milk-based products0.05
USAMilk0.5
References
  1. Administration, U.S. Food and Drug (2015).
  2. Cardona T.D., Ilangantileke S.G., Noomhorn A. FAO Food and Agriculture Organization. Opens external link in new windowhttp://www.fao.org/docrep/X5036E/x5036E1e.htm
  3. Commission regulation (EC) No 1881/2006. Communities, The commission of the European (2006).
  4. Opens external link in new windowhttp://www.fda.gov/ICECI/ComplianceManuals/CompliancePolicyGuidanceManual/ucm074703.htm
  5. Krska R., Nährer K., Richard J. L., Rodrigues I., Schuhmacher R., Slate A. B., Whitaker T. B., (2012). Guide to Mycotoxins featuring Mycotoxin Risk Management in Animal Production. BIOMIN edition 2012
  6. Lemmens M., (2016). Mycotoxin Summer Academy – Module 1. IFA Tulln
  7. Marin S., Ramos A.J., Cano-Sancho G., Sanchis V., (2013). Mycotoxins: Occurrence, toxicology, and exposure assessment. Food and Chemical Toxicology (60) 218-237
  8. Richard J.L., (2007). Some major mycotoxins and their mycotoxicoses - an overview. International Journal of Food Microbiology (119) 3-10
  9. 1. Savard M.E., (2008). Mycotoxins- an introduction. Stewart Postharvest Review 2008 6:1

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