Aflatoxin M1 in bovine milk: screening and confirmation methods for monitoring in Piedmont

Introduction - Aflatoxins are mycotoxins produced by many species of Aspergillus, a fungus, the most notable ones being A. flavus and A. parasiticus. The International Agency for Research on Cancer (IARC) has classified aflatoxin B1 in group of molecules carcinogenic and the substance is considered the most powerful liver-carcinogenic for mammals. Aim - This paper reports the data of the monitoring carried out in Piedmont for the presence of aflatoxin M1 (AM1) in bovine milk. Data are referred to the period 2009-2011 and to different sampling plan, including the National Residues Plan and the Monitoring Plan of raw milk at vending machines. Materials and methods - In the period 2009-2011, a total of 1199 milk samples were analyzed at the laboratory Centro Latte. Among the different monitoring plans, the Monitoring Plan of raw milk at vending machines provided the largest number of samples (74% of the total). Analyses were carried out with ELISA method for a screening step: when samples were suspected to be positive HPLC confirmation was performed. Results and discussion - A total of 16 milk samples (1.3%) were non-negative by ELISA screening method. For these samples the quantitative confirmation analysis by HPLC was carried out: in three cases (one sample in 2009 and two samples in 2010) values exceeding the maximum residual level (MRL) of AM1 have been reported and respectively equal to 57, 82 and 96 ppt; the remaining nine samples gave results within the MRLs. Continuous sampling can monitor the concentration of AM1 in milk and allow to manage any emergencies that may arise. Conclusion - The analytical data of the past three years show that the AM1, with a total percentage of non-compliant samples representing approximately 0.25% of the total, is not a risk for the consumer: the forecasts of climate change suggest that in the coming years there will be an increase in temperature and an altered distribution of rainfall which may favor the development of the main AM1 producers.