Aflatoxin M₁ in milk and its risk in Japan

抄録

A systematic survey of aflatoxin M₁ (AFM₁) in commercial pasteurized milk was carried out for the first time in Japan using immunoaffinity column (IAC) and reversedphase high performance liquid chromatography (HPLC) with fluorescence detection (FLD). A total of 208 milk samples were randomly purchased from retail outlets in 11 regions during the period of December 2001 to February 2002 and analyzed for AFM₁ in 4 independent laboratories. Each milk sample was filtered, and applied to the IAC. After washing with water, the AFM₁ was eluted with acetonitrile and then detected by HPLC-FLD. The identity of the putative AFM₁ was confirmed by the formation of aflatoxin M₁ hemiacetal with trifluoroacetic acid (TFA) and in one sample, the liquid chromatography-mass spectrometry (LC-MS) was performed. Based on the results of spiked samples (0.05μg AFM₁/kg), the mean recovery, relative standard deviation for repeatability (RSD_r) and relative standard deviation for reproducibility (RSD_R) among 4 independent laboratories were found to be as 91.4%, 4.6% and 8.0%, respectively. AFM₁ was detected in 207 (99.5%) out of 208 milk samples ranged 0.001-0.029μg/kg, with a mean level of 0.009μg/kg. No significant difference of the level of AFM₁ contamination was observed among the regions. Based on these data, the risk of development of liver cancer due to AFM₁ contamination in milk was estimated to be lower than 10^-9 per year in Japan.