Mycotoxins pose a threat to food safety worldwide. Because they are considered among the most prominent and dangerous toxins that can affect any part of the food chain—from pre-harvest to food processing —prevention and mitigation of mycotoxin contamination is critical to protect consumers from the adverse health effects associated with these toxins.
“Mycotoxins, such as aflatoxins, are very toxic and present a significant health hazard to consumers,” says Hassan Gourama, PhD, associate professor of food science at Penn State Extension, College of Agricultural Sciences, at Pennsylvania State University in University Park.
With the potential to contaminate a variety of common foods, such as grains (corn, barley, wheat, rice, and oats), nuts, cocoa, and milk, mycotoxins present an ongoing challenge to food safety all along the food chain. The ideal way to mitigate their risk to food safety is to prevent these toxins from entering the food chain at all, and a number of pre-harvest strategies based on good agricultural practices (GAPs) can help.
Even with the best prevention strategies, however, mycotoxins can end up in the food chain given that they are ubiquitous worldwide and that ever-changing environmental conditions preclude strict elimination. “Mycotoxins are naturally occurring toxins found globally and cannot be controlled completely,” says Ronald Niemeijer, MSc, director of global marketing food and feed diagnostics at R-Biopharm AG in Darmstadt, Germany. “The weather conditions prior to harvest play a major role in the risk of mycotoxin production, and globalization of trade flows, as well as climate change, lead to the occurrence of unexpected mycotoxins in unusual products.”
Niemeijer stresses that once mycotoxins enter the food chain, it is nearly impossible to completely remove them during processing, as the toxins are chemically relatively stable. At this stage, detoxification is needed to reduce their level or to partially eliminate these toxins during the food processing stage.
This article describes what mycotoxins are, details the risk they pose to the food chain and human health, explains how to prevent these toxins from entering the food chain, and offers strategies to minimize their risk if they do.
Mycotoxins: Ubiquitous and Challenging
“Mycotoxins are naturally occurring compounds that contaminate food and feed around the world,” says Rebeca Lopez-Garcia, PhD, principal at Logre International Food Science Consulting in Mexico City, adding that the toxins are produced by molds, the most common of which are Aspergillus, Fusarium, and Penicillium.
According to a 2020 review of mycotoxins by Agriopoulou and colleagues, there are currently approximately 400 compounds identified as mycotoxins, and about 30 of these receive the most attention with regard to their threat to human and animal health. Table 1 lists the compounds of most concern, along with the food commodity at risk of contamination with a specific compound.
Among these groups of mycotoxins, aflatoxins are considered the most harmful to human and animal health, says Dr. Gourama. “Aflatoxins have many toxic effects, including acute toxicity, liver cancer, liver cirrhosis, and growth retardation,” he says, adding that symptoms of acute toxicity include abdominal complications, jaundice, pulmonary edema, coma, and death.
Along with the significant health impact, mycotoxins also have a significant economic impact; for example, the value of contaminated crops decreases considerably. “Producers may face export limitations, or lots may be even impossible to sell and have to be destroyed,” says Niemeijer.
As highlighted in the 2020 review by Agriopoulou and colleagues, other significant sources of economic loss include increases in production costs, lowered animal production, irregularity of production, regulatory enforcements, and the need for testing and other quality control measures. Data show that mycotoxin contamination of 25% of the world’s harvested crops costs billions in dollars annually.
Prevention: the First and Best Line of Defense
Once mycotoxins are in the food chain they are impossible to completely eradicate; therefore, prevention is critical. Pre-harvest practices can maintain the health of crops and reduce their susceptibility to fungal contaminants. Dr. Gourama cites several agronomic and management practices that can be applied to achieve this end, including reducing crop residues in the field from the previous harvest (as they can be the initial inoculum for the next crop), using proper irrigation and nutrition to keep crops healthy and less susceptible to fungal invasion, implementing crop rotation to reduce the level of fungal contamination in the field, and planting resistant crop varieties if possible.
Reducing mycotoxin risk at the harvesting stage, he says, includes harvesting grain and seed crops when their moisture content is at its lowest, removing damaged grains/fruits/seeds, and drying grains and seeds quickly once harvested. At the storage stage, moisture and insects need to be controlled and antifungal agents used.
Detoxification: Processing Level
Dr. Lopez-Garcia emphasizes that most mycotoxins are not destroyed or inactivated during processing, so the goal is to prevent highly contaminated products from entering the processing environment.
She recommends that food processors build adequate relationships with suppliers and develop specifications that address mycotoxins. “It’s important to understand each commodity coming into the processing facility and develop specifications that will address the potential contamination,” she says. “It is also important to have proper sampling and analytical methods in place, as sampling is extremely important to obtain reliable results, since some of the toxins may be present in hot spots.” To be valid, she says that samples should represent the whole lot.
She also stresses the need for vigilance in mitigating the risk of mycotoxin exposure in products targeted at infants and children.
Niemeijer also emphasizes the need for sample testing with an appropriate method to get an early indication of the mycotoxin status so that the right decision can be made before the next step in the production chain. “Before accepting a lot, the product can be tested to prevent mycotoxins entering the productions facilities,” he says. “Also, testing before shipping or exporting a product is a good strategy to prevent financial losses.”
Dr. Gourama underscores the need for food processors to obey all GMPs related to their products, particularly for products or ingredients susceptible to mold growth such as peanuts and corn. “Raw material and any incoming products should be checked for any signs of damage, mold growth, and presence of mycotoxins,” he says, adding that a proper cleaning and sanitizing program should always be followed throughout the processing facility to prevent food contamination with molds and potential production of mycotoxins.
Given the enormous impact mycotoxins can have on the food chain, regulatory limits on their levels in food and feed have been established by governing bodies worldwide, including FDA, the European Food Safety Authority (EFSA), the Food Agricultural Organization, and the World Health Association.
Implementing a Hazard Analysis and Critical Control Points approach across the entire food chain and through all stages of food handling is another way to ensure the safety of foods and feed from mycotoxin contamination.