Aflatoxins are a group of highly toxic, naturally occurring mycotoxins produced primarily by the fungi Aspergillus flavus and Aspergillus parasiticus. Classified by the International Agency for Research on Cancer (IARC) as Group 1 carcinogens — proven to cause cancer in humans — aflatoxins represent one of the most significant chemical hazards in the global food supply. Their hepatotoxic and genotoxic properties make them particularly dangerous even at low exposure levels.
Four naturally occurring aflatoxins are most relevant in food safety: Aflatoxin B1 (AFB1), B2, G1, and G2 — named by their fluorescence colour under UV light (Blue or Green) and chromatographic migration pattern. AFB1 is the most toxic and most commonly encountered. A fifth type, Aflatoxin M1 (AFM1), is a metabolite formed in animals that consume contaminated feed; it can pass into milk and dairy products.
Aflatoxins contaminate a wide range of agricultural commodities — groundnuts (peanuts), tree nuts, maize, dried fruits, spices, and cereals — particularly under warm and humid conditions during growth, harvest, or storage. Once formed, they bind tightly to the food matrix. Contamination is irreversible through ordinary food processing. This is why prevention through good agricultural practice (GAP) and routine analytical testing — such as Ovalab’s mycotoxin screening service — is essential for food safety compliance.
Analytical Methods
- HPLC-FLD with IAC Clean-up — High-performance liquid chromatography with fluorescence detection, combined with immunoaffinity column (IAC) clean-up. EU reference method per Commission Regulation (EC) No 401/2006; provides high sensitivity and selectivity for aflatoxins B1, B2, G1, G2, and M1.
- LC-MS/MS — Liquid chromatography with tandem mass spectrometry. Confirmatory method offering high specificity; ideal for simultaneous multi-analyte determination of aflatoxins together with other mycotoxins from a single sample extract.
- ELISA — Enzyme-linked immunosorbent assay. Rapid, cost-effective screening method, particularly suited to high-throughput testing of aflatoxin B1 and M1. Less specific than chromatographic methods; positive results require LC-MS/MS confirmation.
- Lateral Flow Immunoassay — Rapid on-site screening with qualitative or semi-quantitative results within 5–15 minutes. Suitable for incoming goods inspection and field screening, not for official regulatory compliance testing.
EU Regulatory Framework
Maximum levels (MLs) for aflatoxins in food are set by Regulation (EU) 2023/915 (which replaced Regulation (EC) No 1881/2006 in April 2023), Annex I, Section 1. Key maximum levels include:
| Food product | Aflatoxin B1 max. (µg/kg) | Sum B1+B2+G1+G2 max. (µg/kg) |
|---|---|---|
| Most cereals and cereal products | 2.0 | 4.0 |
| Almonds, pistachios, apricot kernels (direct consumption) | 8.0 | 10.0 |
| Hazelnuts and Brazil nuts (direct consumption) | 5.0 | 10.0 |
| Other tree nuts (direct consumption) | 2.0 | 4.0 |
| Groundnuts/peanuts (direct consumption) | 2.0 | 4.0 |
| Dried figs | 6.0 | 10.0 |
| Dried chili, paprika, spice mixes | 5.0 | 10.0 |
| Cereal-based infant and young children foods | 0.10 | — |
| Raw and heat-treated milk (Aflatoxin M1) | 0.05 µg/kg (M1 only) | |
| Infant formula and follow-on milk (Aflatoxin M1) | 0.025 µg/kg (M1 only) | |
The higher limits apply to products destined for sorting or physical treatment before human consumption. Sampling procedures are governed by Commission Regulation (EC) No 401/2006. Maximum levels apply to processed foods consisting of at least 80% of the regulated product.
Frequently Asked Questions
What is the difference between Aflatoxin B1 and the total aflatoxin sum?
EU legislation sets limits for both individual aflatoxins and their sum. Aflatoxin B1 (AFB1) has its own separate maximum level because it is the most toxic and genotoxic form, classified as a Group 1 carcinogen by IARC. The sum of B1, B2, G1, and G2 reflects total dietary exposure to all four naturally occurring forms. For example, in cereals the EU allows a maximum of 2.0 µg/kg for AFB1 alone, and no more than 4.0 µg/kg for the combined total — meaning a sample could have low B1 but still fail the sum limit due to elevated B2, G1, or G2 levels.
Which foods are most at risk for aflatoxin contamination?
Groundnuts (peanuts), tree nuts (especially almonds, pistachios, and Brazil nuts), maize, dried figs, dried chili peppers, paprika, and other spices are among the highest-risk commodities. Aflatoxin contamination is favoured by warm, humid climates and poor storage conditions. Imported food products from tropical and subtropical regions are subject to enhanced EU border controls under Commission Implementing Regulation (EU) 2019/1793 precisely because of elevated aflatoxin risk.
Can aflatoxins be eliminated by cooking or heat treatment?
No. Aflatoxins are thermally stable and are not destroyed by conventional cooking, roasting, or food processing temperatures. Aflatoxin B1 begins to degrade only above approximately 260 °C — far above typical cooking temperatures. Processing such as roasting or baking may reduce aflatoxin levels slightly, but cannot eliminate contamination that exceeds regulatory limits. Prevention through good agricultural practice (GAP), appropriate harvesting moisture levels, and proper storage is the only effective control strategy.
What analytical methods are used to detect aflatoxins in food?
The EU reference analytical method for aflatoxins is HPLC with fluorescence detection (HPLC-FLD), combined with immunoaffinity column (IAC) clean-up, as specified in Commission Regulation (EC) No 401/2006. For multi-mycotoxin screening, LC-MS/MS is the preferred confirmatory method, offering high specificity and the ability to detect numerous compounds simultaneously. ELISA is used for rapid high-throughput screening. All methods used in official control must be validated and performed by accredited laboratories under ISO/IEC 17025.
How does the EU control aflatoxins in imported food products?
The EU applies enhanced border controls to certain high-risk products through Commission Implementing Regulation (EU) 2019/1793 (and its amendments). Products such as groundnuts from certain countries, dried figs, and chili peppers require mandatory documentary checks and physical/identity checks at a specified frequency before being placed on the EU market. Consignments that exceed maximum levels are rejected at the EU border. Food business operators are also required to conduct their own due diligence testing under Regulation (EC) No 178/2002.