X-ray irradiation technique helps control carcinogenic poison in corn

Corn, a staple food crop consumed by billions of people and animals worldwide, is frequently contaminated with the fungal toxin aflatoxin B1, a highly potent carcinogen produced by the fungus Aspergillus flavus.

Exposure to aflatoxin poses serious health risks to humans and other animals, and poses economic challenges to agricultural industries. However, due to the highly transmissible nature of the fungus combined with the toxicity of the toxin, the study and development of laboratory control techniques can be difficult.

In a new study published in the journal ToxinsResearchers at Arizona State University and their international colleagues have demonstrated a promising sterilization technique that uses X-ray irradiation to reduce the viability of Aspergillus flavus in contaminated corn. This method allows sterilization without degrading the harmful aflatoxin B1 (AFB1) produced by the fungus.

By inactivating Aspergillus flavus, the method prevents the fungus from transmitting spores and producing more aflatoxins. This is essential to allow more labs to join the fight against fungal toxins. Stabilizing toxin levels allows scientists to develop and test additional remediation techniques that target aflatoxin degradation without the complication of continued fungal growth. The results showed that a small dose of radiation stopped the fungal growth of Aspergillus flavus.

This work is part of a larger effort by researchers at Arizona State University and international partners to identify low-cost approaches to mitigate aflatoxin transmission and exposure in marginalized communities.

“We’ve known about aflatoxin since the 1960s, but it’s still a pervasive problem,” said Hannah Glesener, lead author of the new study. “X-ray irradiation of naturally contaminated corn is an exciting advancement that supports our research team’s work on developing solutions to aflatoxin-related problems, such as chronic malnutrition.”

Glesener is a graduate research assistant in the Biodesign Center for Health Through Microbiomes and a doctoral student in biological design in the School of Materials, Transportation and Energy Engineering at ASU.

The team is currently evaluating household-scale cooking strategies to control this fungal toxin as well as the role of the human gut microbiome in potentially detoxifying foods before absorption into the bloodstream.

The global challenge of mycotoxin contamination

Aflatoxins are a type of mycotoxin, which are naturally occurring toxic compounds produced by molds or fungi that can grow on a variety of crops. Mycotoxins, including aflatoxins, have potent carcinogenic properties.

Aflatoxins are produced by Aspergillus species and are commonly found in crops such as corn, cottonseed, and nuts, especially in warm, humid environments where molds thrive. Aflatoxin-producing fungi can contaminate crops at various stages, including in the field, during harvest, and during storage.

Aflatoxin contamination is a major global concern, particularly in humid, tropical and subtropical regions. It is particularly prevalent in Africa, Asia and parts of South America, where warm conditions can favour the growth of Aspergillus species.

According to the Food and Agriculture Organization of the United Nations (FAO), 25% of the world’s food crops are contaminated with mycotoxins, including aflatoxins. Nigeria, Kenya, India and China are particularly affected due to their climate and agricultural practices.

Dangerous Health Effects of Aflatoxin Contamination

Acute aflatoxin poisoning, called aflatoxicosis, can occur when large amounts of contaminated food are consumed. Symptoms include liver damage, nausea, vomiting, abdominal pain, and in severe cases, death.

Aflatoxins are particularly associated with an increased risk of liver cancer. The International Agency for Research on Cancer classifies aflatoxins as Group 1 carcinogens, scientifically proven to cause cancer in humans. Chronic exposure can also lead to stunted growth in children and immunosuppression, increasing susceptibility to infectious diseases.

The World Health Organization estimates that aflatoxins are responsible for approximately 5–28% of liver cancer cases worldwide, with the highest burden occurring in sub-Saharan Africa, Southeast Asia, and China. Each year, exposure to aflatoxins is estimated to cause 25,000–155,000 liver cancer deaths worldwide. In addition, the effects of aflatoxin exposure, even at lower levels, are more severe in animals.

Climate change is expected to exacerbate the threat posed by aflatoxins by expanding the geographical distribution of aflatoxin-producing fungi, which could increase the risk of contamination in new regions. In addition, the economic burden caused by aflatoxin contamination is considerable, particularly in developing countries.

Study Overview

The primary objective of the study, led by corresponding author and research assistant professor Lee Voth-Gaeddert, was to determine the optimal irradiation dose needed to eliminate fungal viability while preserving aflatoxin B1 concentrations for subsequent detoxification studies.

These results open new avenues for the safe handling and investigation of contaminated food products without compromising structural and chemical properties essential for scientific analysis. They can hopefully lead to new approaches for scalable and effective solutions to mycotoxin contamination applicable in diverse regions, particularly in developing countries where food safety measures are often limited.