Pistachios, once a treat enjoyed primarily by royalty, can harbour deadly and carcinogenic aflatoxins - but a new nuclear technique has been helping.
Legend has it that the Queen of Sheba, whose empire spanned present-day Yemen to Ethiopia, loved pistachios so deeply that she prohibited ordinary citizens from cultivating them and reserved them exclusively for the royal court. Ancient civilizations, from the Persians to the Greeks and Romans, used this nut not only to cook but also to treat various illnesses such as inflammation. Today, pistachios are more popular than ever. In 2022 alone, over one million tonnes of pistachios were produced globally, with top producers including Iran, the United States and Turkey.
But as demand rises, so does concern over a toxic hitchhiker that the pistachio may carry: aflatoxins.
So how can we continue to enjoy pistachios without worrying about unintended health issues? Enter nuclear technology.
The IAEA and partners have found an innovative nuclear technique to detect these toxins faster, cheaper and more effectively than ever before, making the consumption of pistachios safer for everyone. Being used since 2023, the technique is now applied by more and more countries worldwide.
What are Aflatoxins?
Aflatoxins are chemical compounds produced by mould or fungi which can infect crops such as maize and nuts including pistachio, which is one of the commodities most affected by aflatoxins.. They were discovered in 1960 after thousands of turkeys died from eating contaminated feed in the United Kingdom. These toxins are classified as carcinogens, and long-term exposure to them has been linked to liver failure and tumours. In case of highly contaminated food, aflatoxin poisoning can prove fatal immediately or shortly after consumption.
The pistachio's shell protects it from external contamination. However, during ripening, this shell splits open, exposing it to moulds and insects, increasing the risk of aflatoxin formation and contamination. Aflatoxins are generally invisible to the naked eye, but visible signs of mould on pistachios can include black or grey and black lesions or spots on the hulls or kernels. Contamination can be aggravated post-harvest due to inappropriate storage conditions. As a result, aflatoxin levels are highly regulated in food, with no more than 10 micrograms per kg permissible in pistachios. (Proportionally, that is akin to about a single grain of sugar in a 100 kg sack.)
Conventional testing techniques for aflatoxins are expensive, requiring costly equipment, copious amounts of time and highly skilled technicians. This makes them less applicable to field operations and less accessible for countries with limited resources, a critical gap, especially during food safety emergencies where rapid screening can save lives.
A Lab in a Box
In Seibersdorf, Austria, home to the FAO/IAEA's Food Safety and Control Laboratory (FSCL), experts successfully compiled a toolbox to detect aflatoxins in low-resource settings. The technique employs electrical conductors made from ceramic that are printed with carbon-based ink and contain a sensor to detect four different types of aflatoxins in pistachios. When inserted into a device called a Potentiostat, the sensor can send a small electrical signal when aflatoxins are present, which can then be recorded using a mobile phone. This technique can detect aflatoxins at concentrations that are 150 times lower than the allowed limit, making it a promising tool for screening in the field and rapid risk assessment. The method has been cross-validated with a confirmatory technique - the liquid chromatography-tandem mass spectrometry.
"It's faster, cheaper and doesn't require an entire lab," said Christina Vlachou, Head of FSCL. "That means it can be used in the field, even during emergencies, and in countries that need it most."
A staff member of the Food Safety and Control Lab uses a sensor that can detect contaminants in food (Photo: B. Maestroni/IAEA).
Food Safety and Security in the Face of Climate Change
Climate change is expected to accelerate the spread of mycotoxins like aflatoxins and heavy metal contamination in food, which could have devastating consequences for food safety and public health for countries already struggling with food insecurity,
As global food systems grow more complex and climate risks intensify, countries will need more portable, affordable and scalable tools such as these, especially in regions where conventional laboratory testing is inaccessible.
The IAEA, through its Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture, undertakes research and development to develop nuclear and complementary tools to detect food hazards that threaten food security, trade and public health.
Under the Atoms4Food initiative and in cooperation with the FAO, the IAEA has developed cost-effective and portable techniques that allow for the rapid testing of a large number of samples, including field-deployable tools, to support food safety emergency responses.
Food safety experts in Seibersdorf are working to extend this type of application to cover more categories of contaminants in other food products based on Member State needs. The FSCL has also adapted the same sensor platform to detect fumonisins (harmful mycotoxins linked to cancer and birth defects) in maize and maize products and toxic metals such as lead in fruit juices. This flexibility makes the technique a powerful tool in enhancing food safety.
Vlachou said, "The IAEA is creating resilient and robust interventions to assist food safety stakeholders in countries around the world, maintaining safety and hygiene at required levels to avoid foodborne illnesses."
