Global occurrence of aflatoxin M1 in milk with particular reference to Iran

Aflatoxin M-1 (AFM(1)) is an hydroxylated derivative of aflatoxin B-1 (AFB(1)), which occurs in the milk of lactating animals. The aim of the present study was to determine the concentrations of AFM(1) in raw milk samples collected from 18 dairy farms in Qazvin, Iran, over a period of 1 year and compare them with those found in other countries. Samples (30 per farm) were collected in the four seasons, Spring, Summer, Autumn and Winter occurring between April 2009 and March 2010, giving a total of 2160 samples. They were centrifuged and 100 mu l of the resulting skimmed milk were tested for AFM(1) contamination by competitive enzyme immunoassay (EIA). All samples (100 %) were contaminated with AFM(1) with concentrations ranging from 0.04 to 148.01 ng.l(-1) and a mean of 38.82 ng.l(-1). Summer samples with a mean of 64.69 ng.l(-1) and autumn samples with a mean of 0.14 ng.l(-1) had the highest and lowest concentrations, respectively, and differed significantly (P < 0.05). AFM(1) content in 722 samples (33.4 %) was higher than the maximum tolerance limit of 50 ng.l(-1) accepted by the European Union (EU). As contamination of milk with AFM(1) is a potential risk for human health, raw milk should be monitored for its presence.