Food Safety, residue analysis addressed at Fifth Fresenius Symposium

Experts from the agro-chemical and food industries got together for the fifth international Food Safety and Dietary Risk Assessment symposium.

The Akademie Fresenius (Dortmund) and the SGS Institut Fresenius (Taunusstein) invited scientists and representatives from the industry from both Europe and the U.S. to Cologne, Germany to discuss the latest research findings in the field of dietary risk analysis of pesticide residues.

One of the main topics focussed on by a total of 19 lectures was the assessment of multiple residues in foodstuffs and the harmonisation of EU-wide tolerance levels.

The EU pesticide report published in November 2004 records further deterioration compared to the previous year. Almost half of the fruit and vegetables sold in the EU were contaminated.

In every fourth product tested the EU commission found several simultaneously-occurring pesticide residues. The problem of multiple residues has been keeping the experts busy now for a number of years: common storage of foodstuffs treated in different ways as well as integrated pesticide requirements (i.e. the combined distribution of pesticides with selective effects) have led to an increase in the number of multiple residues being measured. At the same time, analytical procedures are becoming increasingly sensitive allowing smaller and smaller residue concentrations to be determined.

What combined effects result from which individual pesticides is still difficult to estimate. Polly Boon from RIKILT – Institute of Food Safety at the Dutch University of Wageningen presented methods which can be used for determining exposure to harmful substances with the same mode of action and calculating this, using probabilistic analyses. This is done through the implementation of the Relative Potency Factor (RPF). This expresses how toxic a substance is relative to an index compound. A common reference value is the NOAEL (however preferably use Bench Mark Dose levels. If these are not available NOAELs could be used). This represents the highest dose of a substance at which no detectable damage is caused.

If a substance is twice as toxic as the index compound, it has a RFP value of 2. If it occurs together with other substances with the same mode of action in one sample then a total relative value per sample can be calculated. These samples can be used to calculate the combined exposure to these substances which can then, for example, be compared to the Acute Reference Dose (ARfD) of the index compound.

However, Boon said that care should be taken when calculating the combined exposure to more than one compound using probabilistic calculations due to the uncertainties that surround these types of assessments and there is still a need for more research.

A major topic during the congress was the EU-wide harmonisation of the maximum residue levels (MRL) of pesticides in foodstuffs. All EU Member States have to use the same evaluation procedures and licensing criteria during the licensing process. Annexes detailing the current MRLs for around 300 000 pesticide/commodity combinations now form part of EU Regulation 396/2005, which has been in force since 2005 and has replaced national regulations.

Hermine Reich from the European Food Safety Authority (EFSA) provided an insight into the process for finalising the MRLs. Since September the EFSA has been calculating using the harmonised MRL values for 250 substances. To do this they calculate the substance intake amount using the concentration level in the food and the typical amount consumed. In the Mediterranean area the diet comprises different foods in different quantities to those consumed in Scandinavia. Due to the differing food habits in the EU countries, various levels of consumption have to be taken into consideration. Should the calculated values be below the toxic reference value, the currently valid MRLs can then be taken to be safe. The final test results should be available in March 2007.

topics were also devoted to practical measures for reducing pesticide residue contamination. Gillian Asbury from the Food Standards Agency (FSA) in London reported on the FSA’s action plan to minimise residues. Despite the fact that the FSA rates the current level of residues as not being harmful to health, social science studies have revealed that consumer want a lower level of contamination. As a result of its surveys, the FSA has published guidelines to collate best practice on residue reduction (for apples, pears, potatoes, tomatoes and cereals) for the whole food industry from the farmer to the retailer. The target is the communication of practical tips for reducing pesticide residues and ensuring technology transfer.

Reports based on what both the trade and the agro-chemical industry have experienced rounded off the second congress day. Otto Klein from Bayer CropScience AG broached the highly-sensitive subject of exceeding the limits and was able to provide some reassurance. Of the several hundred thousand food specimens tested in EU countries since 1996, only about a handful cases were found to be a possible risk to the consumer. Exceeding the MRL value constitutes, therefore, is a much lower risk, e.g. in a first, very conservative assessment, than the much more common microbiological contamination of foodstuffs.

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