As a means of assessing the performance of European laboratories who contribute analytical data on food contamination to the World Health Organization (WHO) Global Environmental Monitoring Scheme (GEMS), a series of five proficiency testing exercises were carried out during 1993 and 1994. In total 136 laboratories from 21 different countries took part in one or more of the exercises which covered the analysis of trace elements (lead, cadmium and mercury) in milk powder, pesticides (organochlorine, organophosphorus and pyrethroid) in spinach powder, nitrate in spinach powder, aflatoxins in nut-based animal feed and patulin in apple juices. The proficiency testing was carried out according to the ISO/IUPAC/AOAC INTERNATIONAL Harmonized Protocol and laboratories were awarded z-scores signifying their analytical capability based on their reported results for each of the respective exercises. Overall 60% of laboratories were satisfactory for accuracy for trace element analysis, 41% for pesticides, 43% for nitrate, 88% for aflatoxins and 53% for patulin. These results gave an overall poorer performance (68%) than the average for other similar schemes (79%), indicating the need for care in collating data for such programmes as GEMS and the need for remedial measures to assist in improving performance.

Samples of wheat, rye and barley from previous harvests, some of them dating back even to the past century and placed at the authors' disposal by a number of seed growers and governmental research institutions, were examined for their cadmium content by AAS or ICP-AES. Although no statistically valid data could be obtained owing to the low number of samples, it should nevertheless be stressed that the cadmium content found in cereal samples from harvests of the past were within the range of present-day wheat samples. Thus, the variation in wheat samples from former harvests was 20-100 micrograms/kg which is coincident with an average cadmium content of 50-60 micrograms/kg measured in 2000 what samples from the harvests of the last 10 years as determined in a special survey by the Federal Ministry of Food, Agriculture and Forestry. Comparison of the results for cereals samples from harvests of the past and the samples of the survey conducted by the Ministry does not indicate a trend towards a continuously rising cadmium contents of bread cereals.

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Presented here is a rapid method of identifying 4-hydroxycoumarins in organs or blood samples. Using an ultrasonic homogenizer, a complete analysis is obtained in less than 30 min. Coumarin derivatives are identified by means of derivative UV spectroscopy in the normal spectrum and its first derivation at 340 to 240 nm. HPTLC can be employed as supplementary identification method.

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