Aflatoxins are a group of mycotoxins, which are naturally occurring toxic compounds produced by certain species of molds, particularly Aspergillus flavus and Aspergillus parasiticus. These fungi thrive in hot and humid environments, making crops more vulnerable in tropical and subtropical regions.
They commonly contaminate agricultural products such as maize (corn), peanuts, tree nuts, spices, cereal grains, and dried fruits, especially when harvested or stored under poor conditions.

Classification
Aflatoxins are classified into several types based on their fluorescence properties and chemical structure:
- B1 and B2: blue fluorescence under UV light
- G1 and G2: green fluorescence
- M1 and M2: hydroxylated metabolites found in milk (from animals fed contaminated feed)
Among these, aflatoxin B1 is the most toxic, mutagenic, and carcinogenic, and is classified as a Group 1 carcinogen by the International Agency for Research on Cancer (IARC).

Chemical Structure
Chemically, aflatoxins are difuranocoumarin derivatives:
- Their molecular structure includes a coumarin nucleus fused with a difuran ring, sometimes attached to a pentanone ring.
- This configuration is responsible for their biological activity and toxicity in the liver and other organs.
Aflatoxins are produced by certain filamentous fungi, primarily Aspergillus flavus and Aspergillus parasiticus, which are naturally present in soil, plant residues, and organic dust. These fungi thrive in warm, humid conditions and are capable of colonizing a wide range of agricultural commodities, especially when crops are under environmental or mechanical stress.
The spores of aflatoxin-producing fungi are found in:
- Soil and decaying organic matter
- Crop residues left after harvest
- Dust particles during post-harvest handling
These molds can remain dormant for long periods and are reactivated under favorable environmental conditions such as high moisture, elevated temperature, and oxygen availability.
Aflatoxin contamination can occur at multiple stages:
- Pre-harvest : Drought stress, insect injury, or fungal presence during crop growth
- Harvest : Late or improper harvesting increases exposure to mold
- Drying : Incomplete drying promotes mold activity
- Storage : Warm, damp storage environments with poor ventilation allow toxin production
- Transport & Packaging : Moisture reabsorption or condensation can restart mold growth
Commodities most affected include:
- Maize, peanuts, tree nuts, cottonseed, chili peppers, cereal grains, and spices
Understanding both the biological origin of the fungi and the points of contamination along the chain is essential to developing effective prevention strategies.
Aflatoxins are a group of structurally related mycotoxins produced mainly by Aspergillus flavus and Aspergillus parasiticus. They are classified into several types based on their fluorescence under UV light, chemical structure, and toxicity profiles. The most significant types are B1, B2, G1, G2, and M1.

Most toxic and carcinogenic aflatoxin.
Recognized as a Group 1 carcinogen by the IARC (International Agency for Research on Cancer).
Highly mutagenic; forms DNA adducts, particularly in liver cells.
Found in contaminated cereals, nuts, spices, and oilseeds.
Often present in the highest concentrations in contaminated food.
Aflatoxins are among the most potent naturally occurring toxins known to affect human and animal health. Exposure can be either acute (short-term, high-dose) or chronic (long-term, low-dose), both of which have serious consequences.
The International Agency for Research on Cancer (IARC) classifies aflatoxin B1 as a Group 1 carcinogen, indicating strong evidence of carcinogenicity in humans.

Acute aflatoxicosis occurs when large amounts of aflatoxins are ingested in a short period. This is more common in regions where food safety controls are weak or during contamination outbreaks.
Clinical symptoms include:
- Severe liver damage and hepatic necrosis
- Hemorrhaging
- Jaundice
- Vomiting and abdominal pain
- Edema (fluid accumulation)
- Convulsions and coma
- Multi-organ failure
- In extreme cases, death, especially in children or immunocompromised individuals
📍 Notable outbreaks: Acute aflatoxicosis has caused fatal poisoning events in Kenya, India, and Southeast Asia, usually linked to consumption of contaminated maize or groundnuts.

Chronic ingestion of sub-toxic levels of aflatoxins over months or years can lead to progressive health problems, especially when exposure begins early in life or coexists with poor nutrition and other infections.
Key long term effects:
- Hepatocellular carcinoma (HCC): Aflatoxin B1 is a strong risk factor for primary liver cancer, especially in people with chronic hepatitis B infection.
- Immune suppression: Increases vulnerability to infectious diseases by impairing immune cell function.
- Malabsorption and nutritional deficiencies
- Stunted growth and developmental delays in children (especially under 5 years old)
- DNA damage and oxidative stress in vital organs
- Potential reproductive toxicity (under investigation)
Effective detection of aflatoxins is essential for ensuring food safety, regulatory compliance, and consumer protection. Because aflatoxins are potent toxins often found at trace levels, sensitive and specific analytical methods are required to accurately identify and quantify their presence in food and feed products.
Detection Methods
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ELISA (Enzyme-Linked Immunosorbent Assay) | Immunological detection using antigen-antibody binding and enzyme reaction |
| Lower specificity than chromatography |
HPLC (High-Performance Liquid Chromatography) | Separates compounds based on retention time through a chromatographic column |
| Requires trained personnel and solvents |
LC-MS/MS (Liquid Chromatography :Tandem Mass Spectrometry) | Combines separation (LC) and mass analysis (MS) for identification and quantification |
| Expensive equipment and technical expertise |
Fluorometric Detection | Measures natural fluorescence of aflatoxins or via derivatization |
| Less specific, risk of false positives |
Immunoaffinity Column Cleanup + HPLC | Uses antibody columns to purify aflatoxins before analysis |
| Requires multiple steps |

The Codex Alimentarius Commission, established by the FAO and WHO, provides globally recognized food standards. It sets guidelines and maximum permissible levels for aflatoxins in food commodities, which many countries adopt or adapt to their own regulations.
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Example limits:
- 10 µg/kg (ppb) for total aflatoxins in cereals and processed foods
- 0.5 µg/kg for aflatoxin M1 in liquid milk
The European Union enforces some of the strictest aflatoxin limits in the world, under Commission Regulation (EC) No 1881/2006. These apply to both domestically produced and imported products, especially from high-risk countries.
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Groundnuts for direct human consumption | 2 µg/kg | 4 µg/kg |
Tree nuts (e.g., almonds, pistachios) | 2 µg/kg | 4 µg/kg |
Cereals and cereal products | 2 µg/kg | 4 µg/kg |
Dried fruits | 2 µg/kg | 4 µg/kg |
Milk (AFM1) | -- | 0.05 µg/kg |
The U.S. Food and Drug Administration (FDA) sets action levels rather than legal limits, under 21 CFR Part 109. These levels guide food producers and inspectors in determining acceptable contamination thresholds.
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Human food (all products) | 20 µg/kg (ppb) |
Milk (AFM1) | 0.5 µg/kg |
Corn for immature animals | 20 µg/kg |
Corn for breeding livestock | 100 µg/kg |
Corn for finishing cattle (feedlot) | 300 µg/kg |
Many countries align with Codex or EU standards, but some develop their own context-specific policies based on:
Climate vulnerability
Crop exposure
Domestic consumption patterns
Public health priorities
🔹 Examples:
- India: 30 µg/kg for total aflatoxins in cereals
- China: 20 µg/kg for B1 in peanuts and oils
- Kenya: 5 µg/kg in maize for human consumption
- Brazil: 20 µg/kg for aflatoxins in food, 50 µg/kg in animal feed
Reduce risk of liver cancer, stunted growth, and immune suppression
Prevent economic losses due to import rejections and trade bans
Encourage investment in post-harvest management and testing technologies
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Food producers use physical and chemical methods to reduce aflatoxin content:
- Sorting and cleaning of damaged grains
- Thermal treatments (limited effectiveness)
- Binders in animal feed to trap toxins
- Ammoniation and ozone treatment (for feed use)

1. Real-Time Biosensors for On Site Aflatoxin Detection
Traditional aflatoxin detection methods like HPLC or LC-MS/MS are highly accurate but expensive, slow, and require advanced lab settings. New generations of biosensors aim to bring rapid, low-cost, point-of-need detection to farms, storage sites, and food processing facilities.
- Electrochemical biosensors : detect aflatoxins via current changes caused by antigen-antibody interactions
- Optical biosensors : use fluorescence, colorimetry, or surface plasmon resonance
- Nanomaterial-based sensors : using gold nanoparticles, graphene oxide, or quantum dots for ultra-sensitive detection
- Paper-based lateral flow assays : for portable field testing, similar to COVID-19 test strips
To prevent contamination at the source, scientists are exploring ways to make crops genetically resistant to Aspergillus fungi or reduce their ability to produce aflatoxins. Read more
Key Strategies:
- CRISPR/Cas9 gene editing to delete or suppress genes in crops that facilitate fungal infection
- Transgenic maize and peanut lines with improved resistance to Aspergillus flavus
- Silencing aflatoxin biosynthetic genes (e.g., aflR, aflD) directly in the fungus using RNA interference
- Breeding for natural resistance traits in local landraces and hybrids
Machine learning (ML) and AI are transforming aflatoxin risk management by analyzing complex climate, soil, and crop data to predict when and where outbreaks are likely to occur.
How It Works:
- AI models process historical data on temperature, humidity, rainfall, and crop stress
- Predictive alerts are generated for farmers and supply chains to take early action (e.g., early harvesting, better drying)
- Integrated into mobile apps, drones, and remote sensing platforms for real-time analysis
