Introduction
Climate change, or already considered as a “climate emergency or climate crisis”, turns out to be a prominent danger for the safety of food and feed worldwide according to the Emerging Risks Unit of the European Food Safety Authority (EFSA). In fact, the report of the Intergovernmental Panel on Climate Change (IPCC) predicts that global temperatures may increase by up to 4.8ºC in the year 2100. Thus, climate change brings a changing pattern of mycotoxin contamination in cereals such as wheat or corn, a key aspect for food safety, emphasizing the importance of applying good agricultural practices and adequate storage conditions.
The mycotoxin challenge:
Mycotoxins are low molecular weight secondary metabolites produced by specific fungi, mainly Aspergillus spp., Fusarium spp. and Penicillium spp., under certain humidity and temperature conditions.
Mycotoxins present a cause of great global concern due to: (i) their abundant presence in the main food and feed products, such as cereals, (ii) their high chemical stability during feed and food processing, and (iii) their possible negative effect on animal and human health.
The challenge of climate change:
Climate change is a global challenge, especially for agriculture. Due to greenhouse gas emissions, changes in temperatures, precipitation distribution (including more extreme events such as floods and droughts), and humidity levels are being observed. These changes differ depending on the scenario and region, but the generic changes are the following (adapted, Liu and Van der Fels-Klerx, 2021):
| Climate variables | Affected regions |
|---|---|
| 2.5 to 5°C increase with longer dry spells. | Southern Europe, Central Europe, Western and Atlantic Europe. |
| Increase in total precipitation | Regions with high latitudes and tropical regions, and in winter in the northern mid-latitudes. |
| Decrease in total precipitation | Southern Europe and the Mediterranean regions, Central Europe, Central North America, Central America and Mexico, Northeastern Brazil, and Southern Africa. |
| Decrease in average annual soil moisture | The Mediterranean and subtropical region. |
| Increase in average annual soil moisture | Eastern Africa, Central Asia and some other regions with higher precipitation. |
These direct changes in climatic variables further influence crop development, fungal infection, and mycotoxin formation.
What is the relationship between climate change and mycotoxins?
The impact of climate change is expected to increase the occurrence of mycotoxins in human and animal feed.
Although the impact of climate change differs by region, the expected increase in precipitation and temperature in some regions may result in more conducive climatic conditions for Fusarium spp. in Europe. On the other hand, the more frequent and prolonged dry spells expected may stimulate the production of aflatoxins by Aspergillus flavus both before and after harvest.
Prediction models can be mechanistic or empirical. They are usually based on weather patterns (temperature, precipitation, and relative humidity). Based on the literature, quantitative models of mycotoxin incidence in pre-harvest cereals have been reported based on climate change scenarios or long-term climate data in different regions.
Basically, the studies focused on mycotoxins produced by the genus Fusarium (DON/ZEA) in wheat and rice, or aflatoxins in maize (adapted, Liu and Van der Fels-Klerx, 2021):
| Input model | Model output | Crop | Mycotoxin | Region |
|---|---|---|---|---|
| Temperature Precipitation | Percentage of Plants Affected by Fusarium Head Blight (FHB) | Wheat | Incidence of Fusarium Head Blight (FHB) | United Kingdom |
| Temperature Precipitation Relative humidity Flowering date Ripening date | DON concentration at harvest | Wheat | DON | North West Europe |
| “Temperature and relative humidity during blossoming Harvest temperature Region” | ZEA concentration in rice at harvest | Rice | ZEN | South Korea |
| Temperature Radiation, Rain, Soil water and nitrogen level Yield | Aflatoxin Risk Index | Corn | Aflatoxin | Australia |
| Temperature Relative humidity Precipitation, leaf wetness Water activity, Flowering and harvest dates | Aflatoxin cumulative index | Corn and Wheat | Aflatoxin | Europe |
| Temperature Precipitation RH Wind speed Flowering and harvest dates Feed composition | AFB1 concentration in harvest and AFM1 in milk | Corn | Aflatoxin | Eastern Europe |
The results reported by these models, in general, were quite similar in the sense that all studies show an increase in mycotoxins in cereal grains with climate change (Liu and Van der Fels-Klerx, 2021).
Possible applicable prevention measures
There are different strategies to apply good agricultural practices pre-harvest and, thus, prevent the increase of mycotoxins in the fields as a result of climate change:
– Choosing a variety of cereal grain with a flowering schedule depending on the region
– Use a different grain variety that is more resistant to fungal infection.
– If the models predict that the presence of mycotoxins will be extremely high in the future in a certain region, it may be decided to introduce alternative crops in that region.
However, the challenge of mitigating mycotoxins is a great challenge that, on the other hand, has motivated the analysis of these in raw materials, feed and food. Thus, this monitoring is a fundamental support for the use of anti-mycotoxin products, the most efficient solution to mitigate the negative effects of these toxins on animal health and production.
Conclusions
The analysis of climate change scenarios is highly recommended for further investigation in quantitative studies in order to understand the regional differences of these changes in the production of mycotoxins in cereals and, thus, investigate the ways to adapt to these climate disruptions.
Among the possible measures to be taken in the future, it would be useful to make the use of predictive models mandatory to guide adaptation to climate change and ensure that mycotoxin levels in grains remain below legal limits for raw materials, feed and derived foods, as well as to safeguard the safety of feed and food products. On the other hand, the use of more efficient anti-mycotoxin products and an accompanying technical service to measure contamination levels will be essential to mitigate the negative effects of mycotoxins that, derived from climate change, will be more frequent in animal production.
