Occurrence of ochratoxin A in rice sold in chain stores in Tehran, 2007

Mycotoxin contamination of agriculture commodities is a serious concern as regards human and animal health. Rice is a staple food and one of the major carbohydrate sources in the diet of Iranian people. There are reports on the contamination of rice with mycotoxins such as aflatoxins, citrinin, deoxynivalenol, fumonisins B1 and B2, fusarenon-X, nivalenol, ochratoxin A, sterigmatocystin, and zearalenone. In the present study, 100 samples of rice sold in several branches of three of the main chain stores in Tehran, Iran were collected and analyzed for ochratoxin A (OTA). Ochratoxin A was extracted from the samples with acetonitrile-water solvent and purified using the immunoaffinity column. HPLC with fluorescence detector was used to identify and measure the OTA, the detection and quantification limits were being 0.03 and 0.1 µg kg-1 respectively. The OTA content in all the 100 imported and domestic rice samples was 69%. The mean and range of OTA were 1.37±5.72 and 0.15- 46.79 µg kg-1, respectively. In the most samples OTA contamination were lower than the permitted thresholds in cereals according to the Institute of Standards and Industrial Research of Iran (ISIRI) standards. Considering the high contents of OTA in some of the rice samples on the one hand, and the high consumption of other foods contaminated with OTA on the other hand, the total intake of this toxic substance may exceed its Provisional Tolerable Daily Intake as determined by the Joint FAO/WHO Expert Committee on Food Additives. In order to control mycotoxin contaminations, taking pre- and post-harvest preventive measures (GAP, GHP, GSP, GMP and HACCP), as well as sharing experiences and collective effort of all the parties involved, are highly essential.