Aflatoxin M₁ and ochratoxin A in a human milk bank in the city of São Paulo, Brazil

Abstract

Because infants are more susceptible to the adverse effects of mycotoxins, this work was carried out to determine aflatoxin M₁ (AFM₁) and ochratoxin A (OA) in milk from the Human Milk Bank of the Southern Regional Hospital, São Paulo, Brazil. Analytical methods were first established and evaluated. The methods involved the extraction of AFM₁ with methanol and OA with 1% aqueous sodium bicarbonate solution and methanol, clean-up with immunoaffinity columns having antibodies specific for each mycotoxin and quantification by high performance liquid chromatography (HPLC) with fluorescence detection. The method established for AFM₁ had mean recovery percentages of 94, 77 and 82% and coefficients of variation of 17.5, 3.4 and 4.2% at 0.01, 0.03 and 0.05 ng ml⁻¹, respectively. For the OA method, the corresponding values were 84, 84 and 75% for recovery and 14.1, 3.7 and 4.0% for the coefficient of variation. The limit of quantification for both methods was 0.01 ng ml⁻¹. Of a total of 50 samples analysed, only one was contaminated with AFM₁, at 0.024 ng ml⁻¹, and two with OA, at 0.011 and 0.024 ng ml⁻¹. Although the incidence observed was low, it is recommended that the study be extended to other milk banks of the city of São Paulo.

Keywords:

• Aflatoxin M1
• ochratoxin A
• human milk
• analysis

Acknowledgements

The authors would like to thank the employees of the Human Milk Bank of the Southern Regional Hospital, city of São Paulo, for their collaboration in collecting the samples of human milk and for filling out the questionnaires to obtain information about the mothers’ diets.