No abstract

The comparison of the various sources of food contamination with organic chemicals suggests that in the public, but also among experts, the perception of risk is often distorted. Firstly, neither pesticides nor environmental pollutants contribute the most; the amount of material migrating from food packaging into food may well be 100 times higher. Secondly, control of these large migrants is often lagging behind the standards set up for other sources, since many of the components (particularly those not being "starting materials") have not been identified and, thus, not toxicologically evaluated. Finally, attitudes towards different types of food contaminants are divergent, also reflected by the legal measures: for most sources of food contamination there are strict rules calling for minimization, whereas the European packaging industry has even requested a further increase in the tolerance to as close as possible to the limit set by the toxicologists. This paper calls for a more realistic perception and more coherent legal measures-and improvements in the control of migration from packaging material.

A highly sensitive and rapid food-screening test based on disposable screen-printed biosensors was developed, which is suitable for monitoring infant food. The exposure of infants and children to neurotoxic organophosphates and carbamates is of particular concern because of their higher susceptibility to adverse effects. The European Union has therefore set a very low limit for pesticides in infant food which must not contain concentrations exceeding 10 µg/kg for any given pesticide. The maximum residue limit (MRL) has been set to be near the determination threshold that is typically achieved for pesticides with traditional analytical methods. The biosensor method could detect levels lower than 5 µg/kg and thus clearly fulfills the demands of the EU. To substantiate these measurements, recovery rates were determined and amounted on average to 104 % in food.

The validation of an analytical procedure for the determination of pesticide residues in beeswax, an interesting matrix for environmental pollution monitoring, is presented. Using the QuEChERS template, the impacts of wax particle size, sample amount, and cleanup procedure (water addition, dispersive solid phase extraction, freeze-out, and combinations thereof) on extraction yield and coextractive load were studied. Sample preparation through liquid-liquid partitioning between acetonitrile and melted wax (∼80 °C), followed by freeze-out and primary-secondary amine dispersive cleanup, was performed on incurred and pesticide-free samples for 51 residues. Determinations were made through LC-MS/MS and GC×GC-TOF, and the whole procedure was validated. Matrix effects were evaluated, with recoveries between 70 and 120% and RSDs below 20% in almost all cases. LC-MS/MS LOQs ranged from 0.01 to 0.1 mg/kg for most pesticides, but for GC-amenable pesticides, GC×GC-TOF sensitivity was lower (0.1-0.2 mg/kg). This methodology can be applied for routine analysis of pesticide residues in beeswax.

Within the framework of food surveillance a total number of 593 conventionally grown strawberry samples mainly originating from Germany, Spain, Italy and Morocco were analysed for pesticide residues at the Chemisches und Veterinäruntersuchungsamt Stuttgart between 2002 and 2005 using the QuEChERS multiresidue method. Pesticide residues were detected in 98 % of the samples and 93 % of all strawberry samples were found to contain multiple pesticide residues. The German or EU-harmonised MRLs were exceeded by 54 strawberry samples (9 %) with mepanipyrim being the most frequently violative compound. The average total concentration of pesticides per sample was 0.41 mg/kg which is similar to the average value for fruits in general, with Italian products containing the highest and the German ones the lowest residue concentrations. A general trend observed was the decline of the total pesticide residue concentration as the harvest season is progressing.For more efficient analysis, the spectrum of pesticides to be targeted in instrumental analysis was regularly being adjusted to include compounds that are relevant for strawberry samples. The information was extracted from the internet database PesticidesOnline. In total, 105 different pesticide compounds were identified with 65 % of the positive residue findings being <0.05 mg/kg and 96 % of them being <0.5 mg/kg. Fungicides were much more often detected than insecticides and herbicides with cyprodinil, fludioxonil, fenhexamid, tolylfluanid and azoxystrobin being the most frequently detected compounds together accounting for 50 % of the total detections. A toxicological risk assessment with the emphasis on multiple residues was performed using the results obtained for the strawberry samples. Zusammenfassung (Redaktion): Für den Zeitraum von 2002 bis 2005 wurden im Rahmen der Lebensmittelüberwachung insgesamt 593 Proben von konventionell angebauten Erdbeeren mitHerkunft aus Deutschland, Spanien, Italien und Marokko am Chemischen und Veterinäruntersuchungsamt Stuttgart mit Hilfe der QuEChERS-Methode auf Pestizid-Rückstände untersucht. Pestizid-Rückstände wurden in 98 % dieser Proben nachgewiesen und in 93 % aller Erdbeerproben wurden mehr als ein Pestizid nachgewiesen. Die von Deutschland oder der EU festgelegten Höchst-mengen wurden von 54 Erdbeerproben (9 %) überschritten, wobei es sich meist um das Pestizid Mepanipyrim handelte. Die durchschnittliche Konzentration an Pestiziden in den Erdbeerproben lag bei 0,41 mg/kg; grundsätzlich entspricht dieser Pestizidgehalt den Durchschnittswerten von Obst, wobei Erdbeeren italienischer Herkunft die höchsten und die deutscher Herkunft die niedrigsten Konzentrationen an Pestizidrückständen aufwiesen. Außerdem konnte festgestellt werden, dass generell im Verlauf der Erntesaison die Konzentration an Pestizidrückständen in den Erdbeerproben abnimmt.Das Analyseverfahren für den Nachweis der Pestizidrück-stände wurde auf das für die Erdbeerproben relevante Pestizidspektrum optimiert. Dazu wurden Informationen aus der Internet-Datenbank "...