Aflatoxin M1 (AFM1) is the monohydroxylated derivate of aflatoxin B1 that, toxic and carcinogen compound. The aim of this study is to measure the amount of aflatoxin M1 in the country\\\'s productive sectors in different seasons of the year. The study was cross sectional study and carried out during 2016-2017. 175 raw milk samples were collected by referring to industrial dairy farm of a number of provinces of the country by simple random sampling in different seasons of the year. Aflatoxin M1 was measured in HPLC method and compared to specified standards in Iran (0.1 µg/l) and the European Union and codex (0.05 µg/l). Aflatoxin M1 was found at 151 samples (86.29%). The average of aflatoxin M1 in samples was 0.19 ± 0.009 with a range of 0.001 to 0.45 µg/l. 49.14% and 65.14% of studied samples were the aflatoxin M1 concentration higher than the standard of iran and the european union and codex. The maximum amount of aflatoxin M1 was (0.237±0.11 µg/l) during the summer and lowest during the winter (0.024±0.004 µg/l). There was a significant difference between the mean of aflatoxin M1 during the summer and fall season with the winter season (p<0.05). The study showed that half of the cases of raw milk in the country contaminated with aflatoxin M1 were excessive, and that was very worrisome. Thus, the regular monitoring of the fungal infections of the genus Aspergillus in livestock feed, which is the main source of the production of aflatoxin poison.

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