Ochratoxin A (OTA) is produced by the fungi Aspergillus ochraceus and Penicillium verrucosum. Its presence is normally associated with poor storage conditions rather than developing in the field. Prevention is achieved by drying and cooling grain promptly after harvest and ensuring that it remains in this condition throughout the storage period. Advice to farmers on how to minimise the risk of storage mycotoxins developing is available in the AHDB’s Grain Storage Guide.  UK millers only purchase grain from farmers who operate under assurance schemes, in which they are expected to follow this guide.  This ensures the risk of grain containing high levels of OTA entering the food chain is minimised.

All UK flour millers remain vigilant and carry out ‘due diligence’ monitoring procedures (using rapid tests) to check for any potential OTA contamination when grain arrives at a mill.  If levels of OTA exceed the legal maximum, the grain is rejected.  nabim routinely surveys OTA levels in milling wheat using confirmatory methods  as part of the AHDB monitoring project.

EU legal OTA Limits

If consumed at high levels, OTA can have a distructive effect on the kidneys. The European Food Safety Authority (EFSA) therefore decided, in 2006, on a tolerable weekly intake (TWI) for OTA of 120 ng/kg bodyweight.

The EU has also set legal limits for OTA in various foodstuffs as follows:

  (OTA (µg/kg)
Unprocessed cereals 5.0
Products derived from unprocessed cereals 3.0
Processed cereals based foods and baby foods 0.5
Foods for special medical purposes intended specifically for infants 0.5