What are mycotoxins? Mycotoxins are metabolites that are produced by fungi and that are highly toxic for humans and animals. The fungi that can produce mycotoxins are mainly the Aspergillus, Penicillium and Fusarium genera, but also the Claviceps and Alternaria ones. These fungi are very widespread, present in almost all environments. They can occur in fields, in storage facilities, but also in many interiors. They will contaminate agricultural commodities, mainly during crop cultivation or during storage. The ecological role of mycotoxins is still an open question today. What is known is that for some mycotoxins, such as deoxynivalenol, produced mainly by Fusarium graminearum, the toxin will help the fungus to invade the plant host tissue. Actually, deoxynivalenol is able to inhibit the defense that plants employ to counteract the fungus. For other mycotoxins, there is also strong suggestion that these mycotoxins will confer a competitive advantage to the producing fungi when they will co-occur with bacteria or other fungi. Lastly, there is also a large body of evidence suggesting that mycotoxins can contribute to the fungus to adapt to hostile environments. However, the mechanisms that can explain this role are today poorly understood. Humans are mainly exposed to mycotoxins through the consumption of contaminated food and mainly contaminated plant-based products. These mycotoxins have a very wide range of toxic effects related to chronic or acute toxicity. They can include disorders in some functions of key organs, such as kidneys, liver, dysfunctions in the reproductive system, dysfunctions in the immune system and also some cancers. For instance, aflatoxin and to a less extent fumonisin and ochratoxin have been associated with cancer development, while deoxynivalenol is mainly associated with perturbations in the immune system and zearalenone will mainly affect the reproductive system. To answer this question, two main criteria are required to be considered. First, toxicity of the mycotoxin and second, the prevalence of the mycotoxin so the consumer exposure to this mycotoxin. If we consider these two criteria, aflatoxin is by far the most dangerous mycotoxin. Actually, aflatoxin is the sole mycotoxin for which it has been recognized a carcinogen effect for humans. And aflatoxin has been also reported as a causal agent of outbreaks of liver cancer in South America, but also in Africa. If we now consider the European consumer, due to the high prevalence of deoxynivalenol, this mycotoxin is certainly at the highest concern. But it is important to know that in Europe, there is a European regulation set since 2006 and in this regulation there are some maximal limits for the main of the mycotoxins and therefore this regulation aims to protect the consumer from the adverse effect of mycotoxins. This regulation, however, does not include what we call emerging mycotoxins since for these mycotoxins, the toxicity is insufficiently documented. And this regulation also does not consider the mixture of mycotoxins, which is really a common situation. And the challenge to evaluate, to assess toxic effect of such mixture of mycotoxins is currently a high challenge addressed by toxicologists. Yes, of course, when the conditions are favorable for the development of the fungi, but also for its production of mycotoxins, and if nothing is done to stop the fungi development or to stop this production, the mycotoxins will multiply.