Corn is a staple crop globally, but its vulnerability to mold raises serious health concerns. The danger is not the fungal growth itself, but the toxic chemical compounds certain molds produce, known as mycotoxins. These naturally occurring toxins contaminate the corn kernel in the field or during storage, posing a risk to both human and animal health. Understanding the specific fungi and the toxins they create clarifies why this common agricultural issue requires careful management and strict regulation.
The Fungal Culprits and Mycotoxin Production
Mycotoxins are toxic compounds produced by filamentous fungi. Two fungal genera are the primary culprits in corn contamination: Aspergillus and Fusarium species. The most potent is Aflatoxin, primarily produced by Aspergillus flavus, which often appears as a greenish-yellow or olive mold on the kernels.
Aflatoxins are classified as Group I carcinogens due to their strong link to liver cancer. Aspergillus flavus thrives when the corn plant is stressed by hot, dry weather and high temperatures, especially during the grain-fill stage. This combination makes the crop susceptible to infection and toxin production.
Fumonisin mycotoxins are produced mainly by Fusarium verticillioides, a fungus common in corn fields worldwide. Fusarium infection typically presents as a white, pink, or salmon-colored mold, often associated with streaks on the kernels. These fungi infect the plant through the silk channel or via insect damage.
Fusarium species generally grow best in moderate temperatures, unlike Aspergillus which favors hot and dry conditions. However, contamination is exacerbated by warm and dry weather during the flowering and grain-fill periods. The toxins are very stable and remain in the corn even after the mold is killed or removed.
Immediate and Long-Term Health Consequences
Ingesting corn contaminated with mycotoxins can lead to immediate illness or long-term chronic diseases. Acute exposure, resulting from consuming a large dose, can cause aflatoxicosis. Symptoms include nausea, vomiting, abdominal pain, and in severe cases, acute liver failure and death.
The most significant risk comes from chronic, low-level exposure, particularly to Aflatoxin B1. This toxin is a major risk factor for hepatocellular carcinoma, the most common type of liver cancer. This risk is dramatically elevated, up to 60 times higher, in individuals who also have a chronic Hepatitis B virus infection.
Fumonisins are associated with other serious health risks, including an increased risk of esophageal cancer. There is also concern about the toxin’s potential to cause neural tube defects and impair child growth. This makes infants and pregnant women particularly vulnerable populations.
Mycotoxins are found across the food chain, including in products derived from animals that consumed contaminated feed, such as milk. The toxic compounds are metabolized by the liver, making it the primary site of damage. Even low doses ingested regularly contribute to the cumulative lifetime risk of developing chronic illness.
Visual Identification and Safe Handling Practices
Consumers can sometimes spot mold on corn, but visual cues are not a reliable indicator of mycotoxin presence. Aspergillus mold may appear as a powdery, grayish-green or yellow-green growth, often found at the tip of the ear. Fusarium infection can look white, pink, or salmon-colored, sometimes scattered across the kernels.
Any corn showing discoloration, fuzzy growth, or an unusual musty odor should be discarded immediately. Since mycotoxins are odorless and tasteless, contaminated corn can look perfectly healthy. Never attempt to smell or taste a suspected moldy product, as this risks exposure to a high concentration of the toxin.
Mycotoxins are not destroyed by standard cooking or heating processes, so trimming the moldy part off is not a safe solution. The toxins can spread invisibly throughout the kernel and to adjacent kernels that appear clean. The safest practice for noticeably moldy corn is to double-bag it and dispose of it in the trash, preventing consumption by humans or animals.
How Food Safety Regulations Protect Consumers
The low incidence of acute mycotoxin poisoning in regulated markets is due to stringent food safety regulations. Regulatory bodies, such as the Food and Drug Administration (FDA), set strict limits called action levels for mycotoxins in food and animal feed. These levels dictate the maximum permissible concentration of a toxin before a product is removed from the market.
For Aflatoxin, the FDA has set the action level for corn intended for human consumption at 20 parts per billion (ppb). This limit is established to minimize chronic exposure risk based on scientific data regarding the toxin’s potency. Corn that exceeds this level cannot legally be sold for human consumption.
The regulatory structure for mycotoxins in animal feed is often more complex than for human food, with different action levels depending on the species and age of the animal. These regulations ensure that contaminated corn is directed to appropriate uses or destroyed. This systematic testing and rejection process is the primary defense against widespread exposure.