Mycotoxin exposure in a changing European climate

What are mycotoxins?

Mycotoxins are toxic compounds that are naturally produced by the Aspergillus, Penicillium, Fusarium and Claviceps fungi species (WHO, 2018; Battilani et al., 2020). They are metabolic by-products and occur as contaminants in agricultural products all over the world (Bennett and Klich, 2003; Wu et al., 2014).

Certain fungi are responsible for the major classes of mycotoxins linked to health concerns, in particular aflatoxin B₁ (AFB₁), DON, Fumonisin B₁ (FB₁), zearalenone (ZEN) and ochratoxin A (OTA) (Cinar et al., 2019). DON, a trichothecene, is frequently found in wheat, maize and barley in temperate regions. FB₁ occurs mainly in maize, wheat and other cereals (Battilani et al., 2016; HBM4EU, 2022a; Khan, 2024).

This briefing will focus primarily on the health impacts of DON since human biomonitoring data for its health effects are available due to the results of HBM4EU.

How mycotoxins impact health

An overview of the health effects associated with exposure to DON and FB₁, and the strength of evidence for each one split across different genders and ages as well as the relevant exposure routes, can be found in Figure 1.

Figure 1. Overview of the health effects associated with exposure to DON and FB₁ and possible exposure routes depending on the various exposure scenarios

Mycotoxins are concerning for the general population and workers (in farms, warehouses, and food and feed factories). Some are associated with carcinogenic, mutagenic, reprotoxic (CMR) and immunotoxic effects, as well as kidney and liver toxicity in humans; some are also suspected of disrupting the endocrine system (IARC, 2002; Cinar et al., 2019; Martins et al., 2021). These effects are associated with specific mycotoxins and much of the currently available evidence comes from animal studies.

DON and ZEN are concerning for human health and environmental safety. ZEN is a potential endocrine disruptor as it mimics estrogen, causing reproductive issues in humans and animals (Bucheli et al., 2008; Gromadzka et al., 2009; Kowalska et al., 2016). OTA, considered a post-harvest mycotoxin, has been linked to kidney damage and cancer, especially in populations exposed to it via drinking water (Al-Gabr et al., 2014). Post-harvest is what follows crop production after harvest and it involves cooling, cleaning, sorting and packing steps to prevent deterioration. However, more research is needed to fully assess its persistence and bioactivity in aquatic environments.

Evidence suggests that certain groups may be at higher risk from exposure to mycotoxins. Young children (1 – 3 years old) and infants (under 12 months old) are especially vulnerable due to their higher food intake relative to body weight (EFSA et al., 2017). Mycotoxins are found in cereal-based baby food and tomato products, and thus dietary exposure for this group is considered a public health concern (EFSA, 2011). Since babies are smaller, unwanted exposure has greater consequences and they are more at risk of harm. Potential damage to the kidneys (from OTA) and the liver (from aflatoxin (AF) and AFB₁) is a concern in the very young, whose renal and hepatic systems are still developing (Kyei et al., 2020; Sarron et al., 2020). Pregnant people are also vulnerable: foetal exposure may also have negative health effects, since some mycotoxins travel through the placenta and the blood-brain barrier (Kyei et al., 2020; Sarron et al., 2020).

Workers in the agricultural and food and feed sector constitute another vulnerable group. They may be exposed to mycotoxins in contaminated dust both through inhalation and the skin, resulting in acute exposure (Fromme et al., 2016; Viegas et al., 2018).

Human exposure to mycotoxins in Europe

The main source of exposure to mycotoxins is through diet, mainly by eating contaminated food (particularly grains and cereals, and their derivatives). Recent studies suggest that while approximately 25% of crops exceed EU regulatory limits for mycotoxins, contamination can occur at levels above the detectable limits in up to 60-80% of crops (Eskola et al., 2020). 

Mycotoxins are absorbed by plants during growth or after harvest and can remain in food even after washing, cooking or processing. This is because some are resistant to heat and typical food preparation methods. Although people usually discard visibly mouldy food, the fungi that produce mycotoxins are not always visible, making it challenging to remove them once contamination has occurred (Santos et al., 2022). Since they are also odourless and tasteless, contamination is hard to detect without testing.  

Inhalation and absorption through the skin are also potential exposure routes occurring particularly in occupational settings. Figure 2 illustrates the main sources of exposure.

Figure 2. Overview of main exposure sources of mycotoxins

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Another source of mycotoxin exposure is through the environment. Research has increasingly identified mycotoxins as emerging contaminants in surface and drinking water, leading to further investigation into how they enter these water systems (Székács, 2021).  

Mycotoxins can enter water systems through agricultural runoff (from contaminated crops), wastewater or improper disposal of contaminated products. In wastewater, some mycotoxins (e.g. OTA) are not adequately removed by treatment processes and can persist. This has implications for drinking water safety (Al-Gabr et al., 2014). Although their stability in water varies, some mycotoxins, including DON and ZEN, can persist in the environment, potentially posing a risk to water sources including lakes, rivers and groundwater (Waśkiewicz et al., 2012).  

The European Food Safety Authority (EFSA) has undertaken an assessment of human exposure to DON, establishing a tolerable daily intake (TDI) of 1 mg/kg body weight per day for the sum of a group of three types of DON. The EFSA estimated that mean chronic dietary exposure was found to be above the TDI in infants (less than 12 months), toddlers (1 – 3 years old) and other children (3 -10 years old), and at high exposure in adolescents (10 – 18 years old) and adults (18 – 65 years old) thus indicating a potential health concern (EFSA, 2017). 

One outcome of HBM4EU was the development of a Human Biomonitoring Guidance Value (HBM-GV) for DON in the adult population’s urine. This value represents the level of internal exposure above which health effects may occur; it allows for a robust assessment of whether there are possible risks to health. A provisional HBM-GV of 23 µg /L of total urinary DON for adults was derived that should be regarded as a guidance value that can be used to assess whether the European population is at risk (Alvito et al., 2022; HBM4EU, 2022b). This value.  

HBM4EU monitoring found that DON was detected in 14% of the adult participants in the six European countries that were studied. Country-level data indicate that parts of the adult population in Poland and, to a lesser extent, in Luxembourg, France and Portugal are very likely to be exposed at significantly risky levels, raising potential health concerns. One notable observation from the monitoring was that more highly educated adults tend to have lower exposure to mycotoxins. This may be linked to greater awareness of balanced diet and lifestyle choices among this group (Govarts et al., 2023). These differences within populations may also be explained by differences in diet and the fact that exposure, even at low doses, occurs almost continuously over a lifetime.  

Data from Germany and Iceland did not identify a health risk as they were below the HBM-GV (Schmied et al., 2023). However, the study did not involve equal numbers from different socio-economic backgrounds according to the International Standard Classification of Education (ISCED). Overall, only 6.6% of participants had a low educational level, 30.8% fell into the medium category and 62.7% were highly educated (Namorado et al., 2024). 

Data from HBM4EU provide information on the total internal dose of exposure and could be used as a baseline for exposure of the European population to mycotoxins against which progress can be measured (Namorado et al., 2024). These types of data could potentially be used to develop national and Europe-wide biomonitoring programmes on mycotoxins, to protect the environment and human health from an increase in exposure resulting from climate change.

Figure 3. Mycotoxin concentration exceeding the HBM-GV in six European countries and percentage of the overall adult population above the HBM-GV (23 μg/L)

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Mycotoxins and climate change

Since the 1980s, Europe has been warming twice as fast as the global average, making it the fastest-warming continent on the planet (EEA, 2024). All regions in Europe have experienced warming and this trend is projected to continue. By the end of the century, Europe as a whole is projected to experience further warming of between 1.5 °C (low-emissions scenario) and 4.5 °C (high-emissions scenario) (EEA, 2022, 2024).  

From a geographical perspective, the highest risk of climate-change-induced mycotoxin contamination is expected in developed countries with moderate climates (Kos et al., 2023). Certain mycotoxins, like AF, DON, ZEN and OTA, are expected to become more prevalent at higher temperatures in humid conditions. This is because humidity spurs the growth of fungi responsible for producing these mycotoxins (Battilani et al., 2016; EFSA, 2020; Moretti et al., 2019; Sundheim et al., 2017).  

Studies have been carried out to predict the impact of climate change on AF contamination in maize, wheat and rice in the EU based on the current meteorological scenario, and under +2°C and +5°C increases (Battilani et al., 2012). Under a +2°C temperature-increase scenario, the study predicts that AF contamination in maize will increase, particularly in southern Europe (Spain, Italy and the Balkans). In a +5°C scenario, the contamination risk may decrease in southern regions due to extreme heat, but risks will widen geographically to include more northern European countries. For wheat, there are also increases in AF contamination, but these are higher in a +2°C temperature-increase scenario than a +5°C scenario (although with the latter, they are still higher than in the current meteorological scenario). For rice, the risk of contamination is negligible at harvest for all scenarios.  

This change of the spread of fungal species in Europe will alter exposure patterns, resulting in people being exposed to different mycotoxins with varying health effects (Assunção et al., 2018; Assunção and Viegas, 2020). Contamination from multiple mycotoxins, including mixtures of AFs, fumonisins, DON and ZEN, is expected to increase in crops, escalating human dietary exposure (Moretti et al., 2019; WHO, 2018; EFSA, 2020; Battilani et al., 2020).  

The types of Fusarium fungi found on wheat in Europe are constantly changing across northern, central and southern Europe, with particular concerns about the increasing presence of F. graminearum in central and northern Europe (Kos et al., 2020, 2022; Pleadin et al., 2023; Battilani et al., 2012). The EFSA anticipate that the effects of climate change on mycotoxin occurrence will vary by region; they foresee potential small increases in terms of the impacts and moderate increases in the likelihood of mycotoxins emerging in new areas. For DON and ZEN, they predict a moderate impact in the near-future scenario which ranges from 2021-2050 projected by different climate models (EFSA, 2020). However, it remains challenging to accurately predict the effects due to the complex interactions of multiple factors (Kos et al., 2023; Pleadin et al., 2020). 

Increased precipitation, flooding and soil erosion could also transfer these toxins from soil to rivers and groundwater. This would increase the likelihood of contamination in food and feed, and amplify the risk of mycotoxins finding their way into the drinking water system (EFSA, 2020; Al-Gabr et al., 2014; Gromadzka et al., 2009). When average temperatures climb and more extreme weather events take place, such as heavy rainfall or prolonged droughts, plant stress increases, making cereals — especially maize — more vulnerable to fungal infections and mycotoxin contamination (Kos et al., 2023).  

Climate change is also expected to cause potential increases in the prevalence and geographic distribution of insect populations (Bebber et al., 2014; Bebber and Gurr, 2015; Magan et al., 2012). Insects play a role in spreading toxigenic moulds, thus increasing the likelihood of crop infections and contamination (Kos et al., 2023). 

The potential impacts of climate change on mycotoxins in Europe may also have consequences from an economic and food security perspective. Increased crop contamination will lead to lower yields, with associated economic losses. These may include higher costs for sampling, testing and recalls, which will disrupt food and feed security patterns and trade at both EU and global levels (COCERAL, 2023).  

Climate change may also impact crop patterns, with producers growing different crops which are better suited to the changing agri-environmental conditions. This may have unexplored consequences for the environment and food safety.  

According to a statement from the Food and Agriculture Organization prior to 1985, it was estimated that 25% of the world's crops were affected yearly by mycotoxins, with losses estimated at 1 billion metric tons of food and feed products (Patriarca and Fernández Pinto, 2017; Maestroni and Cannavan, 2011). However, recent studies indicate that the number is likely higher, as up to 60-80% of food crop samples have detectable levels of mycotoxins (Eskola et al., 2020). There is also a wider global threat: mycotoxins present a significant risk in areas such as sub-Saharan Africa, a humid region where food security is already a major issue. Here, increased AF contamination could lead to substantial agricultural losses (Van der Fels-Klerx et al., 2016; Casu et al., 2024). In the case of maize, climate-induced AF contamination has been linked to major food safety concerns, which could also affect international trade. 

Finally, a growing risk of fungal infections could trigger increased fungicide use, requiring enhanced monitoring of fungicide residues and a re-evaluation of the risks they pose to the population (EFSA, 2020). Such risks may include antifungal resistance and, therefore, a global increase in human fungal diseases with significant loss of food crops and livestock to fungal pathogens.

Case studies

The case studies below provide data to inform our understanding of how climate change and environmental conditions influence mycotoxin contamination and the resulting risks for humans, animals and the environment.

• Portugal: A study by Viegas et al. (2020) detected mycotoxin contamination in animal feed used on a dairy farm. The study investigated exposure to multiple mycotoxins (ZEN, DON and OTA), including how workers are affected. It highlighted that the use of uncontaminated feed can prevent workers and animals from exposure and avoid milk contamination. This illustrates how a One Health approach can help implement preventive and control measures that can be effective in different contexts, such as occupational health, food safety, animal health and public health.
• The Netherlands: The Wageningen Food Safety Research group specialises in natural toxins. It developed an early warning system for crops and fisheries to predict the regional presence of toxins (mycotoxins, fycotoxins and phytotoxins) and the effects of climate change on the quantity of toxins in the environment (WUR, 2023).

These findings highlight the need for proactive management and control of AFs to reduce exposure, as climate change increases the risk of contamination in European crops.

Preventive measures: mycotoxins and One Health

One Health is an approach that recognises the complex interconnectedness of human, animal and environmental health. Its application aims to prevent and respond to health threats by safeguarding plants, animals, ecosystems and human health simultaneously (EEA, 2023).

A One Health perspective has recently been applied to mitigate the impact of azole fungicide use (other than as human medicines) on the development of azole‐resistant Aspergillus species (EFSA, 2025). Aspergillus are fungi commonly found in the environment which can cause severe respiratory diseases in humans. These diseases are treated with azole medications. However, azoles are also used in plant protection, with around 10,000 tonnes used per year in the EU between 2010 and 2021. The EFSA (2025) report makes recommendations relating to the areas of agriculture, medicine, and biocide and fungicide approval processes to limit the spread of azole resistance.

The case of mycotoxins is a clear example of an issue that has potentially far-reaching consequences for animal, human and ecosystem health, with the environment also playing a key role as a pathway for the spread of contamination. Solutions to address the risks from mycotoxins must therefore be incorporated across all areas. For example, surveillance already undertaken in the environment (e.g. precipitation, sunlight hours, temperature records) should also be done to monitor food, animal feed, animals and humans. Other possible actions to counteract mycotoxin contamination could include breeding crops that are resistant to fungal infection, adopting GAPs, making use of biological controls and predictive models (Casu et al., 2024).

Breeding fungi-resistant crops is critical in managing mycotoxin contamination (Gasperini et al., 2019). Most of the research related to crop development is already based on genetic and biotechnological approaches designed to handle environmental stresses caused by climate change. This includes work on, for example, drought-resistant crops. In this context, it is important to carry on developing robust, pathogen-resistant crops (Casu et al., 2024; Hameed et al., 2022; Wambui et al., 2016).

GAPs, like tailoring farming practices to adapt to new environmental conditions, are of the utmost importance. These include changes such as adjusting harvest periods, modifying irrigation requirements, and appropriate use of pesticides and fertilisers. For example, in Spain, tomato harvesting may be shifted to earlier months due to increasingly high summer temperatures. Cropping strategies like intercropping and crop rotation have also been suggested as effective approaches for controlling fungal pathogens.

Biological control of mycotoxins focuses on using non-toxic strains of fungi that compete with aflotoxigenic fungi for resources and space, thus reducing AF contamination. The use of biocontrol agents has proved successful in the USA, Africa, Italy and Serbia (Casu et al., 2024; Jallow et al., 2021; Mauro et al., 2018; Ajmal et al., 2022; Savić et al., 2020; Pickova et al., 2021).

Predictive models are also a useful tool for managing the impact of climate change on mycotoxin contamination as they assess plant-pathogen interactions under climate change conditions. For example, the DONcast model predicts the risk of DON contamination based on local weather data. Likewise, another study commissioned by EFSA developed a model to predict the risk of AFB₁ contamination in maize at harvest; it has been further adapted for wheat and rice (Casu et al., 2024; Battilani et al., 2012). Such models allow for more timely agricultural interventions, like applying fungicides. As climate change progresses, these models will help farmers and policymakers anticipate future mycotoxin risks and adapt accordingly.

All the actions support the development of more integrated mitigation strategies to avoid mycotoxin contamination, and to maintain food security and water safety under climate change. They support the adoption of a One Health approach to address the interrelated effects of mycotoxins on human, animal and environmental health. A preventive approach involving consumer awareness campaigns as well as other stakeholders such as farmers and industry should also be promoted (Mukhtar et al., 2023).

This type of effort requires a collaborative approach from different partners and joint policy initiative. Such collaboration could help farmers and policymakers alike anticipate the risks and take action to protect human and animal health, and the environment.