Survey of mycotoxins in stored grain from the 1999 harvest in the UK

Abstract

A survey of stored grain was carried out to determine the levels of two mycotoxins, deoxynivalenol (DON) and ochratoxin A. The first of these substances is produced by naturally-occurring fungi or moulds which attack the growing crop, such as Fusarium ear blight. The second is produced by moulds growing on the grain during storage. Both present a risk to human and animal health. The European Commission is currently considering proposals for legislative limits for both of these contaminants but more information is needed on their normal levels in grain. Consequently the Home-Grown Cereals Authority commissioned a survey of UK grain in store from the 1999 harvest to see how the levels compared with the proposed limits. Samples of grain were collected across the UK from farms, central stores, mills, maltings and ports from the beginning of February to the beginning of April 2000. A total of 320 samples was collected, consisting of 201 wheat, 106 barley and 13 oats, which is approximately proportional to the hectares of each grown in the UK. A small number of organic samples was also collected.

For DON the limits under consideration include 500m g/kg for retail products such as breakfast cereal, bread, pasta, etc. and 750m g/kg for grain or any grain product (such as flour) used as a raw material by industry (1m g/kg is 1 part per 1,000,000,000). Analyses of the samples showed that none exceeded 750m g/kg of DON but one exceeded 500m g/kg with a level of 600m g/kg. The proposed limit for ochratoxin A is 5m g/kg, in line with its much greater toxicity relative to DON. The great majority of samples (97%), including all of the organic samples, had levels of ochratoxin A which were below the proposed limits. Measurable levels were present in 16% of samples but only 3% were above the limit. However two samples had significantly higher levels of more than 100m g/kg. Finally, a limited study was made of the range of trichocenes found in the higher contaminated DON samples. The results indicated that DON was the major trichothecene present.

These results represent a snap-shot in time, in terms of both the length of time since harvest and the year of the survey, which provide a base-line for comparison with the proposed limits and with any future surveys.