Estimated exposure to EU regulated mycotoxins and risk characterization of aflatoxin-induced hepatic toxicity through the consumption of the toasted cereal flour called “gofio”, a traditional food of the Canary Islands (Spain)
Graphical abstract
Introduction
Products from agriculture, particularly cereals, are susceptible to infestation by various species of microscopic fungi (Aspergillus, Penicillium, Fusarium, and Claviceps spp.), which can produce mycotoxins directly on the plant before harvest, during harvesting, during storage, during processing, or during storage of the processed foods (Oliveira et al., 2014). More than 400 different mycotoxins are known, and most mycotoxins are immunosuppressive agents and some are carcinogens, hepatotoxins, nephrotoxins, and neurotoxins (Marroquin-Cardona et al., 2014). Various mycotoxins are specially worrisome because of their powerful toxic properties, so that they can pose a danger to public health, and are of great concern because large economic losses resulting from their presence (Rubert et al., 2013). Among mycotoxins with the greatest toxicological relevance, as well as those that produce the greatest economic losses to the agricultural sector, aflatoxins (AFs), ochratoxins (OTs), fumonisins (FBs), trichothecenes, and zearalenone (ZEA) are probably the most relevant (Azaiez et al., 2015, Marroquin-Cardona et al., 2014). There are currently ten mycotoxins that are regulated in the European Union (EU) because of their high toxicity (AFB1, AFB2, AFG1, AFG2, Deoxynivalenol (DON), FB1, FB2, Ochratoxin A (OTA), ZEA, and patulin). For all of them, except for patulin, maximum limits (MLs) are set in cereals, both raw and processed (Table 1), giving approximately 50 mycotoxin/matrix combinations (EC, 2006). There is also a recommendation of the European Commission for an extension to T2 and HT2 trichothecenes, which also proposes limits for these mycotoxins in cereal flours and their first-processing derivatives (except rice) (Table 1) (EC, 2013).
According the FAO, in Western Europe cereals take a second position among the staples in the average diet, accounting for around 26% in terms of total energy supply (Alexy et al., 2010). In many societies the cereal staples of the diet consist on different types of flours (Ranum et al., 2014). In the Canary Islands (Spain) food called “gofio” is a non-sifted flour made from roasted grain, usually wheat or corn, which is used in a variety of food preparations, although mostly consumed as breakfast cereals. It has been a staple food for the population of the archipelago for centuries (Hernandez et al., 2014), and is still the most traditional food of the Canary Islands. This staple is consumed regularly by many of the 2.5 million inhabitants of the archipelago and occasionally by the more than 10 million tourists receiving these islands annually (Caballero et al., 2014, Hernandez et al., 2014). This food is so important, that the Canary Islands government has approved the designation of origin “Gofio Canario” under the EEC Regulation 2081/92 on designations of origin and geographical indications for agricultural and food products (EEC, 1992, Hernandez et al., 2014). In addition to the valuable nutritional properties of this cereal flour (Caballero et al., 2014), Dominguez-Rodriguez et al. (2015) investigated its cardioprotective role, and found that the regular consumption of gofio is associated to an increase of resistance to exercise and a decrease of the coronary risk in the elderly (Dominguez-Rodriguez et al., 2015). Unfortunately, in a recent study investigating the presence of mycotoxins (fumonisins) in more than 1200 samples of cereal-based foods from three European countries, the authors found the highest concentrations and incidence of these mycotoxins in the samples of gofio (Rubert et al., 2013). However, it is also worth to note that all the samples of gofio included in that study were from organic production, and it has been established that the prevalence of certain types of mycotoxins, such as those produced by Fusarium spp., is higher in cereals from organic agriculture (Serrano et al., 2013).
According to the EFSA, monitoring studies evaluating the presence of mycotoxins in the different types of foods that can contain them are a continuous necessity, to allow the risk characterization associated to those food commodities (EFSA, 2013a, EFSA, 2014). EFSA recommends that risk characterization of a particular food is made by comparing exposure scenarios with reference doses of the parent compounds, using the lower bound (LB) and upper bound (UP) approaches, and considering the mean and 95th percentile exposures to the sum of modified and parent toxins (EFSA, 2014). Following the recommendations the calculated exposure values should be compared with the established Tolerable Daily Intakes (TDIs)/Provisional TDIs (PTDIs)/Provisional Maximum TDIs (PMTDIs) in order to evaluate the risk of exposure through the consumption of a particular food (Yogendrarajah et al., 2014). For most regulated mycotoxins the TDIs have been calculated (Marroquin-Cardona et al., 2014), except for aflatoxins, because of the known fact that AFB1 is a genotoxic carcinogen, and therefore exposure at any level is considered unsafe (Yogendrarajah et al., 2014). However, despite its uncertainty a PMTDI of 1 ng/kg B W./day has been proposed for AFB1 (WHO, 1998). For the rest of regulated mycotoxins associated with cereal-based commodities, the reference values set by the EFSA are: DON = 1000 ng/kg B W./day (TDI) (EFSA, 2013b); FB1 + FB2 = 2000 ng/kg B W./day (PMTDI) (EFSA, 2014); OTA = 17.1 ng/kg B W./day (PTDI derived from the PTWI) (EFSA, 2006); ZEA = 250 ng/kg B W./day (TDI) (EFSA, 2011b); T-2 + HT-2 = 100 ng/kg B W./day (TDI) (EFSA, 2011a).
Although there is a wide range of publications on the occurrence of mycotoxins in cereal based foods available in Europe, as well as on the risks associated with the consumption of the same, there is no study of this type available for the gofio. Therefore, the present study aims to evaluate the presence of multiple mycotoxins in this food commodity and the characterization of the risks associated with the intake of this staple of the Canary Islands.
Section snippets
Sampling
A total of ninety-four packages of gofio (1 kg) were randomly purchased from different retail outlets located in the seven Canary Islands. None of the samples had surpassed their expiration date. The chosen gofio samples were made from corn (n = 45); wheat (n = 23); and mixture of the two cereals (n = 26). Seventy-two samples were from conventional production (37 corn, 19 wheat, 16 mixture of cereals), and 22 samples were from organic production (8 corn, 4 wheat, 10 mixture of cereals). Until
Method validation data
The LC-MS chromatograms showed a good resolution for target analytes and no peaks appeared at the retention times of analytes that can interfere in their quantification. As expected using the stable isotope dilution technique for quantification, matrix effect was not observed for none of the studied mycotoxins. In Supplementary Table 2 we summarize the main data obtained from validation experiments. All the correlation coefficients (r2) were higher than 0.99, and the RSD lower than 15% for all
Conclusions
The results of this study revealed that the levels of mycotoxins in gofio imply a low daily intake (<1% TDI) for the average consumer, except in the case of aflatoxins. However, in the worst-case scenario (intense consumers and UB approach) a relevant percentage of the TDI (∼10%) is reached for FBs and DON, and a high percentage of TDI (>35%) is reached for AFs. Worringly, our results indicate that there may be a potential risk in developing liver cancer due to AFs exposure via gofio in a
Competing financial interests declaration
There are no actual or potential conflicts of interest to declare for any author.
Acknowledgements:
This work has been funded by the Cooperative Research and Development Project PERVEMAC (MAC/3/C282) granted by the European Regional Development Funds (MAC 2007-2013) in the framework of the PCT-MAC Program.
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