Aflatoxin M1 contamination in winter and summer milk in 14 states in Iran

During February and August 2004, 319 raw milk samples were collected from dairy farms and milk collecting centers of 15 dairy plants in 14 Iranian states in winter and summer. Samples were analyzed for aflatoxin M1 with a validated high performance liquid chromatography (HPLC) method. The recovery at 0.05 μg/kg was 68% and coefficient of variation (CV) was 15%. The recovery at 0.5 μg/kg was 81% and CV was 25%. Aflatoxin M1 contamination was detected in 54% of the field samples. The sample-mean concentration of aflatoxin M1 was 0.057 μg/kg with 0.014 standard deviation and sample median 0.039; 44% of the samples had levels <0.01 μg/kg and 77% were <0.05 μg/kg. The levels of contamination in industrial and traditional dairy farms were equal, but the season had an indirect effect (α ⩽ 0.05) on the levels of contamination on the farms. The level of contamination in winter was significantly (α ⩽ 0.1) higher than in summer.