Estudio analítico de aflatoxinas y elementos traza potencialmente tóxicos en cereales destinados a alimentación animal e infantil

Abstract

This research studies the exposure to various contaminants of high toxicity in different food matrices: Aflatoxins (B1, B2, G1 and G2) and the metallic elements (lead, cadmium and mercury) and metalloids (arsenic) in cereals for animal feed (n=78) and infant feeding (n=91). The aims of this work were to: 1. Validate a chromatographic method for the determination of aflatoxins and optimize the atomic absorption spectrometry technique for the estimation of Pb, Cd, Hg and As in various arable matrices. 2. Study the influence of several factors in the compounds analyzed in the animal feed samples obtained from farms. 3. Evaluation of the degree of exposure to these substances, establishing the theoretical intake level and the biotransformation of aflatoxin M1. 4. Determine the contents of aflatoxins and potentially toxic trace elements in the cereals and evaluate the main sources of pollution. 5. Establish the contribution of the pollutants of the different cereals to the infant¿s diet. Compare with the values of the Provisional Tolerable Weekly Intake (PTWI). The HPLC method meets all validation criteria. With regard to animal feed, in any case the AFB1 level of the studied samples exceeds the legislation (5 µg Kg-1). The content of aflatoxins and potentially toxic trace elements has not varied to a certain extend with the geographic situation. Spring is the most disadvantaged climatic season (AFB1: spring 0,086 (0,030;0,130); winter 0,075 (0,037;0,130); summer 0,030 (0,005;0,082) and autumn 0,017 (0,002;0,031) ng Kg-1) and the animal feed self-produced by farmers is more appropriate. None of the feeding strategies employed by the dairy cattle provides striking dietary intake values and the theoretical extrapolation of biotransformation in AFM1 predicts only a positive value (53,43 ng Kg-1). Finally, the factorial analysis gets five principal components that explain 70,8 % of the total variability of the system. On the other hand, infant foods have a high incidence of aflatoxin total (81 % of the analyzed infant cereal). Seven and three infant cereal formulations exceed the legislated limit for aflatoxin B1 (0,1 µg Kg-1) and lead (200 µg Kg-1), respectively. The distributions of organic cereals have aflatoxins and potentially toxic elements contents higher than the conventional ones (Ecological: AFB1 0,022 (0,016;0,212); Pb 26,1 (21,4;51,6); Cd 18,5 (16,6;28,5); Conventional: AFB1 <LD (n.d.;0,019); Pb 10,8 (6,4;19,3); Cd 7,1 (4,4; 11,8) µg Kg-1). If the infant cereal is separated according to the different varieties that exist at different stages of growth, cocoa is revealed as the main source of contamination. An organic formulation based on cocoa exceeds the maximum intake of 1 ng Kg-1 and this is related to a high risk of liver cancer. The PTWI provided by conventional cereals has no risk unlike three ecological formulations. Three principal components explain 82,9 % of the total variance. The three-dimensional graphical representation of the various factors allows a clear classification of organic and conventional cereals. Scatter diagrams of the discriminant functions provide a good classification of both cocoa and gluten-free based cereals, and depending on the type of predominant cereal, it is possible to discriminate quite well between the gluten-free (rice and corn based) and gluten based cereals.