Limited survey for aflatoxin contamination of polished rice imported into Japan

Analysis of aflatoxins (AF) B1, B2, G1 and G2 in imported polished rice samples from Thailand, Pakistan and Bangladesh was performed by direct competitive ELISA (direct cELISA) and immunoaffinity column with high performance liquid chromatography (IAC-HPLC) methods using monoclonal antibody. Direct cELISA method with the detection limit of 2.8 μg/kg for AFB1 gave negative results in all of 20 samples analyzed. On the other hand, using IAC-HPLC with the detection limit of 0.1 μg/kg for each toxin, AFB1 was detected in five out of 20 (25 %) imported polished rice samples; in three Thailand and two Pakistan samples, with the concentrations ranging 0.1 - 0.3 μg/kg. In addition, AFB2 (0.1 μg/kg) was detected in one of the Pakistan rice sample contaminated with AFB1 (0.3 μg/kg). Even though the level of AF contamination in imported rice samples found to be well below the Japanese limit (10 μg/kg), AF contamination in rice as a staple food of Asian is an important issue for evaluation of human exposure due to the frequency of intake.