Aflatoxin M1 contamination and antibiotic residue in milk in Khorasan province, Iran

The aim of this study was to evaluate aflatoxin M1 (AFM1) contamination and antibiotic presence in milk samples in Khorasan province in Iran. During 4 months (March to June 2008), one hundred ninety-six milk samples were collected from seven dairies. The occurrence and concentration range of AFM1 in the samples were investigated by competitive enzyme-linked immunoabsorbent assay (ELISA) method. Antibiotic presence was determined using Copan test, a broad-spectrum test capable of detecting beta-lactams, tetracyclines, sulfonamides, aminoglycosides and macrolydes. AFM1 was found in 100% of the examined milk samples by average concentration of 77.92 ng/kg. The concentration of AFM1 in all of the samples were lower than Iranian national standard and FDA limit (500 ng/L), but 80.6% of the samples had AFM1 greater than the maximum tolerance limit (50 ng/L) accepted by European Union and Codex Alimentarius Commission. Statistical evaluation showed no significant difference between the mean concentrations of AFM1 of milk samples taken from different factories (P > 0.05). Copan milk test was positive for 40.8% of the samples.