Summary of CaDON
Cadmium (Cd) and mycotoxins are among the most worrying contaminants that threaten the safety of food products derived from cereal kernels. Indeed, as recently supported by the last French total diet survey (Anses, 2011), deoxynivalenol, or DON, and Cd human exposure through food mainly results from the consumption of cereal-derived products. Cd is a highly toxic trace element naturally occurring in soils. Cd is also added to soils by natural and industrial atmospheric deposition, as well as agricultural inputs in the case of agro-systems. Once present in agricultural soils, Cd is readily absorbed by wheat roots and translocated to edible parts where it accumulates. Regarding mycotoxins, cereal contaminations with DON in Europe are mainly caused by the toxigenic filamentous fungus Fusarium graminearum that develops on growing crops. Given the toxicities of both Cd and DON, their respective levels in commercialized cereal grains for human consumption are strictly regulated in Europe (EC No 1881/2006 and No 856/2005). Durum wheat is the most sensitive cereal culture for both DON and Cd accumulation in kernels. More than 10 % of the French durum wheat annual production can have DON concentrations above the European limit of 1750 μg/Kg1, depending on the considered year. Regarding Cd, up to 30 %1 of the 2011-2013 durum wheat harvests was estimated to be above 0.1 mg/kg, which was the value considered for the downward revision of the current regulation limit. Moreover, 29 % of the French 2011-2013 production was shown to contain significant amounts of both DON and Cd. This frequent co-occurrence combined with the fact that Cd and DON are likely to be distributed in the same milling fractions raises the concern of consumer exposure to the cocktail Cd+DON. Despite intensive research investigating long-term toxicity of chronic expositions to low concentrations of both contaminants individually, the toxicity of Cd+DON together has never been addressed. It is currently unknown whether the toxicity of Cd modifies that of DON, and inversely. Nevertheless, the levels of both Cd and DON must be reduced in the food chain in general and in cereals in particular, in order to protect the consumer against their toxicological adverse effects and help actors of the cereal sector to deliver cereal products that comply with the European regulation limits.
By tracking cereals and derived-products contaminations by both Cd and DON, from field to final milling products, as well as their toxicity upon ingestion, the objectives of the CaDON project are: i) to insure that strategies implemented to reduce the concentration of one contaminant do not favor the contamination by the other, both at the level of agricultural practices and at that of the milling processes, ii) to investigate whether the co-contamination of cereal products by both Cd and DON results in a “cocktail effect” leading to interactions in the toxicity to mammals. To attain these objectives, three fields of research have been defined with three specific and highly complementary aims: (i) to survey and understand the occurrence of co-contaminations from the field to the milling fractions, (ii) to decipher the biological and physiological bases that could explain the co-contaminations of kernels and fractions, (iii) to assess the toxicity of the Cd+DON cocktail using in vitro and in vivo models. These three fields of research are implemented and combined in an integrative federative approach combining analytical epidemiological studies (data mining of occurrence surveys) and mechanistic approaches (plant ecophysiology, microbiology, food processing and toxicology).
Ultimately, expected outputs of the CaDON project include i) knowledge gain for reducing co-contamination frequencies in the field (cultivar selection, agronomical practices) and limiting the contents of Cd+DON in wheat-derived products through fractionation processes, and ii) assessment of the combined Cd+DON toxicity to mammals. As a whole, CaDON’s outputs will provide an estimate of the risk for food safety associated to Cd and DON in durum wheat grain as well as the bases to understand how this risk builds from the field to the consumer, therefore providing crucial elements for the identification of actions to minimize such risk.
INRA, UR 1264 MycSA, coordinateur -(http://www6.bordeaux-aquitaine.inra.fr/mycsa/)
INRA/INP UMR 1331 ToxAlim (http://www6.toulouse.inra.fr/toxalim/)
INRA/CIRAD/ Montpellier SupAgro UMR 1208 IATE (http://umr-iate.cirad.fr/)
INRA/Bordeaux Sciences Agro UMR ISPA 1391 (http://www6.bordeaux-aquitaine.inra.fr/ispa/)