Occurrence of aflatoxin M1 in pasteurized milk of the School Milk Project in Thailand.

Concentrations of aflatoxin M1 (AFM1) were determined in 150 pasteurized milk samples from the School Milk Project in Thailand. Milk samples were collected from 50 schools in the Central region of Thailand in three seasons: summer (May to June 2006), the rainy season (August to September 2006), and winter (December 2006 to January 2007). AFM1 was isolated by using an immunoaffinity column and quantified by high-performance liquid chromatography. All of the 150 pasteurized milk samples were contaminated with AFM1, and the concentrations were within the U.S. regulatory limit of 0.5 microg/liter. The highest concentration of AFM1 found in school milk samples was 0.114 microg/liter. The mean concentration of AFM1 in milk samples collected in winter was significantly higher than the mean concentrations found in the rainy season and summer. Further monitoring of school milk to evaluate the status of contamination of AFM1 is necessary, with a special emphasis on samples collected in the rainy season and winter. Thailand is one of several countries that have no regulatory limits for AFM1 in milk and milk products. The results of this study suggest that safety limits for AFM1 are needed for regulating and ensuring the quality of milk and milk products in Thailand.