Aflatoxin B1 and its interconverting metabolite aflatoxicol in milk:: the situation in Mexico

Between 1996 and 1998, 580 litres of milk in Mexico were surveyed for aflatoxin B 1 (AFB 1 ) and its metabolite aflatoxicol (AFL), which are mutagenic and carcinogenic mycotoxins that interconvert AFB 1 -AFL-AFB 1 . The seven most consumed brands from different regions of Mexico included pasteurized and ultrapasteurized milk with four different fat levels: whole fat (28-33 g l -1 ), half-skimmed (10-20 g l -1 ), light (1-4 g l -1 ) and with vegetable oil (33 g l -1 ). Aflatoxins in each sample were concentrated with total aflatoxin immunoaffinity columns and quantitated by high-performance liquid chromatography. A milk sample was considered contaminated if it contained greater than or equal to0.05 mug l -1 AFL. Pasteurization and ultrapasteurization of milk did not control contamination with AFL, which was present in 13% of samples at greater than or equal to0.05 mug l -1 and in 8% at greater than or equal to0.5 mug l -1 , with a range of AFL from 0 to 12.4 mug l -1 . AFB 1 was present mainly in traces (0-0.4 mug l -1 ). The safest milk in relation to AFL contamination was imported milk powder with vegetable oil. There was a significant correlation between contamination of milk with AFL and the autumn ( p <0.0002); the fat content was not significant.