Resumo

CASTRO-GONZALEZ, Numa Pompilio et al. Heavy metals in milk from cows fed alfalfa produced in soils irrigated with wastewater in Puebla and Tlaxcala, Mexico. Rev. mex. de cienc. pecuarias [online]. 2018, vol.9, n.3, pp.466-485. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v9i3.4358.

The objective was to determine the presence of Cd, Pb, Ni, Cu, Cr, Zn and As in the food chain of cow's milk, produced in areas where alfalfa is cultivated in irrigated soils with industrial, domestic and agricultural wastewater. Soil and alfalfa were sampled from 16 sites located in four zones; milk was collected from 160 cows, corresponding to 40 cows from four different herds per zone, all in two seasons of the year and in triplicate. The bioaccumulation factor (BCF), the translocation factor (TF) and the transfer value of the metals from the plant to the milk were calculated. The plants had a BCF <1, indicating that alfalfa is resistant to heavy metals. However, the TF >1 in decreasing order was left as follows: Zn; Cu; Ni; Pb and Cr, which shows the existence of great mobility of metals within the plant. The milk had a Pb content in a range of 0.039 ± 0.02 to 0.059 ± 0.05 mg kg-1, values ​​above the international allowed limit. However, the levels of Pb and As were lower than the permissible values ​​by the Official Mexican Standard. It is concluded that alfalfa is an accumulator plant and resistant to heavy metals and when it is cultivated in contaminated soils, it becomes an important medium for the transfer of heavy metals to animals and they are eliminated through milk.

Palavras-chave : Bioaccumulation; Translocation; Heavy metals; Food contamination; Milk.

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