Pesticides in foodstuffs

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Changed on: 02.05.2017

Pesticide residues are investigated using chemical trace analysis methods in the Department of Pesticide and Foodstuff Analysis (PLMA) at the Institute for Food Safety Innsbruck (LSI). Here a distinction is made between qualitative detection, i.e. answering the question as to whether a particular substance (analyte) is present in the sample being tested or not and quantitative detection, i.e. clarification of the quantity of a particular substance present in the sample being tested. Foodstuffs that have the designation “organic” are not permitted to have any detectable synthetic pesticides or pesticide residues.

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Pesticide residues are investigated using chemical trace analysis methods in the Department of Pesticide and Foodstuff Analysis (PLMA) at the Institute for Food Safety Innsbruck (LSI). Here a distinction is made between qualitative detection, i.e. answering the question as to whether a particular substance (analyte) is present in the sample being tested or not and quantitative detection, i.e. clarification of the quantity of a particular substance present in the sample being tested. Foodstuffs that have the designation “organic” are not permitted to have any detectable synthetic pesticides or pesticide residues.

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Situation in Austria

Comparison with previous monitoring programmes shows a pronounced drop in the number of times maximum limits have been exceeded since 2008. Statutory maximum limits that have been harmonised across Europe prevent the importation of severely contaminated goods into Europe, in addition to which, pesticide reduction programmes in the trade chains and improved agricultural practice by the producers have contributed to an increasing quality of foodstuffs in Austria.
For more information, refer to the Pesticide Monitoring Reports.

Legal basis

The monitoring of foodstuffs for contamination with pesticides is fundamentally regulated by the EU: plant protection product residues in EU member states are tested on the basis of the Control Programme coordinated across the EU, in which annually alternating goods are to be analysed as a matter of principle for the presence of specific pesticides and their breakdown products. Monitoring is also carried out on the basis of national objectives: Austria specifies an obligatory national monitoring programme every year.

If the measured concentration of a pesticide is significantly in excess of a stipulated maximum limit, then the foodstuff sample tested is flagged as unacceptable. The setting of maximum limits and the design of the control programme are intended to protect consumers as much as possible from potentially harmful substances. Since not all pesticides and all breakdown products from pesticides are equally harmful to humans, clear distinctions must be made here. As well as toxicity data, consumer exposure is also taken as a basis - in the form of customary consumption behaviour, which is established in surveys and is continually being updated. Previous measurement results are also taken into account. To enable as extensive a degree of monitoring of Austrian foodstuffs as possible, a statistical approach is taken during sampling. Foodstuff imports from non-EU countries (import inspections) in particular are closely scrutinized for possible contaminations. In Austria sampling is carried out by trained inspectors from the regional official food supervisory authorities of the federal states. During sampling it is important to ensure that the sample is representative of the entire batch, so that in case of contamination of the foodstuff the relevant batch can be tested or sale of the contaminated batch can be prohibited.

As of 1 September 2008 the maximum residue levels of pesticides in food and feed have been harmonised across all EU member states following commencement of Regulation (EC) No. 396/2005.

Authorisation for certain particularly dangerous substances, e.g. endosulfan or quintozene, was withdrawn following a re-evaluation of the possible risks. Their use is therefore no longer permitted.

Due to legal amendments and additions to the list of active substances, constant further development of the existing analytical procedures is indispensable. Both single and multi-methods are being developed and optimised not only nationally but also in the international network of reference laboratories. The LSI has firmly established itself in national and international research partnerships, thus ensuring that in the future it can provide a service in consumer protection - at the cutting edge of research.

Pesticide Residue Analysis

Residues of plant protection products must be isolated from their “matrix”, i.e. from the food or feedstuff, using suitable sample preparation techniques and if necessary enriched. The sample is initially homogenised in the laboratory. The resultant homogenate is extracted with a suitable solvent so that the plant protection product residues are dissolved out of the matrix.

The extract can now be further separated using chromatography (gas or liquid chromatography) and tested using mass spectrometry methods. Modern high performance mass spectrometry equipment (e.g. MS/MS) is used in order to allow reliable and precise identification of the smallest possible quantities of analyte. The MS/MS procedure in combination with the gas or liquid chromatography procedure allows definitive identification and quantification of a chemical compound.

With the use of special sample processing procedures, simultaneous identification of hundreds of analytes is possible - these instances are referred to as “multi-methods”. Different processing methods may be used for different groups of foodstuffs (e.g. feed and cereal, meat, fish, fruit): differences in the matrices necessitate a variety of procedural methods of isolating the analytes. Certain analytes, however, cannot be extracted from the matrices using these processing procedures or react to breakdown products during sample processing, such that the concentration of the substance identified in these cases differs greatly from the concentration actually present in the foodstuff sample. The number of these pesticides, however, is limited, so it is possible to resort to so-called “single methods”. Single methods are processing and measurement procedures that were developed specially for “difficult” analytes which preclude identification using multi-methods.

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