Survey and risk assessment of aflatoxins and sterigmatocystin in Japanese staple food items and the evaluation of an in-house ELISA technique for rapid screening

Aflatoxins and sterigmatocystin (STC) are carcinogenic mycotoxins frequently detected in many kinds of agricultural products. An analytical method for the simultaneous detection of these mycotoxins was developed using immunoaffinity chromatography clean-up and LC–MS/MS techniques to assess the health risks associated with the exposure to aflatoxins and STC present in staple Japanese food items. A survey targeting Japanese staple food items, including rice and wheat, was conducted after validating the analytical method by conducting a single-laboratory test. A total of 550 samples were analyzed. Aflatoxins were not detected in all samples, whereas STC was detected in 22.4% of the tested samples. The dietary exposure to STC was estimated based on the results of the survey, and the amount of food intake ranged from 0.11 to 0.67 ng/kg body weight/day. The results obtained following the margin of exposure (MOE) approach revealed that STC in staple food items posed little risk to the general Japanese population. In addition, an ELISA technique for detecting STC in brown rice and wheat samples was developed, as high levels of contamination were observed in these food items. The performance of the developed ELISA technique was evaluated using STC-spiked samples, and the average recoveries were in the ranges of 94.6–121.2% for brown rice and 91.5–117.9% for wheat. The LC-MS/MS technique was used for analysis, and a rapid screening technique based on ELISA was efficiently utilized for assessing the health risks associated with exposure to these carcinogenic mycotoxins.