Antibiotic residues and aflatoxin M1 contamination in milk powder used in Tehran dairy factories, Iran

The presence of aflatoxin M1 (AFM1) and antibiotic residues in milk and milk products is a public health concern. Milk and milk powder have the potential for introducing AFM1 and antibiotic into human diet. In recent years, milk powder has been used on a large scale in dairy factories. Consequently, antibiotic residues and aflatoxin contamination control in these products has gained importance. The aim of this survey was to determine the level of β-lactam and tetracycline antibiotic residues and also AFM1 contamination of milk powder used in Tehran dairy factories. During 12 months (September 2011 to September 2012), 240 samples of milk powder were collected from ten Tehran dairy factories. All samples were analyzed for the presence of AFM1 using ELISA technique. In addition, antibiotic residues were determined by BetaStar Combo test, a rapid assay for both β-lactam and tetracycline antibiotics. The samples depicted positive results i.e. 30% and 17.5% for β-lactam and tetracycline antibiotics, respectively. Also, AFM1 was found in 155 cases (64.6%) with an average concentration of 29.85 ± 18.99 ng/ L. The results showed the milk powder used by dairy factories is safe in respect of AFM1 contamination and antibiotic residues in Tehran.