Seasonal Variation of Aflatoxin M1Contamination in Raw, Pasteurized and School Milk in Shahrood, Iran

Background and Aflatoxin M1 is a toxic compound that is placed in class IIB (carcinogenic) by the WHO- International Agency for Research on Cancer, so its monitoring in milk is a great public health issue. The purpose of this study was to determine the concentration of aflatoxin M1 in raw, pasteurized milk and samples of milk produced for school milk project in Shahrood, Iran. In this descriptive-analytical study, 130 raw milk samples were collected from 4 collection centers and 14 production sites. Also, samples of 28 pasteurized milk from 3 producing company and 13 samples prepared for school milk project (in autumn and winter) from two brands were collected in summer and winter and analyzed by HPLC-fluorescence following immunoaffinity purification. In samples of raw milk the mean concentration of Aflatoxin M1 in summer and winter were110.3± 137.5 and 24.8± 36.51ng/kg, respectively. In summer and winter the level of Aflatoxin M1 contamination in pasteurized milk and school milk were 52.1± 36.6, 16.8± 13.0, 28.1 14.8, and 32.5± 171ng/kg, respectively. In all samples significant differences were observed between seasons. The minimum and maximum levels of aflatoxin M1 in raw milk were determined zero (undetectable) in winter and 743 ng/kg in summer, respectively. Significant differences in the mean concentration of aflatoxin M1 in studied seasons, indicates the necessity for appropriate monitoring on animal food in summer and winter and more controlling measurements in summer on type, processing and storage of animal food.