For an overview over contamination events check
Regulation 1829/2003 - Section 2 Labelling, Article 12:
"1. This Section shall apply to foods which are to be delivered as such to the final consumer or mass caterers in the Community and which:
(a) contain or consist of GMOs; or
(b) are produced from or contain ingredients produced from GMOs.
2. This Section shall not apply to foods containing material which contains, consists of or is produced from GMOs in a proportion no higher than 0,9 per cent of the food ingredients considered individually or food consisting of a single ingredient, provided that this presence is adventitious or technically unavoidable.
3. In order to establish that the presence of this material is adventitious or technically unavoidable, operators must be in a position to supply evidence to satisfy the competent authorities that they have taken appropriate steps to avoid the presence of such material."

One crop, one country, and officially only for one year, 9 years ago - and yet there is contamination. On 8 September 2009, German authorities notified the other EU member states that they had found unathorized GM flax (linseed) in a shipment from Canada via Belgium (RASFF 2009.1171). The flax (FP967/CDC, Triffid) is herbicide-tolerant, but to a different class of herbicides then usually used with GM crops, and it carries an antibiotic resistance gene as marker.

Using agro-biotechnology causes high costs for the whole food production chain: through higher seed prices, methods to avoid resistance development, separation production chains and analyses. In additions there are damages of several billion US dollars in maize and rice production caused by contamination with non-approved gene constructs. Small as they are, financial gains of GM crops can only achieved over short periods.
This study provides information from a survey among German food producers and retailers as well as details of costs and damages caused by a number of contamination cases.

Christoph Then & Antje Lorch (2009): "Schadensbericht Gentechnik", 65p.
Report for the BÖLW

[img_assist|nid=170|title=|desc=|link=none|align=right|width=100|height=43]Die Nutzung der Agro-Gentechnik verursacht hohe Kosten in der gesamten Lebensmittelkette: durch steigende Saatgutpreise, Maßnahmen zur Vermeidung von Resistenzbildung, Trennung der Warenströme und Analysen. Dazu kommen Schäden in Höhe von einigen Milliarden US Dollar, die bei Mais und Reis durch Kontaminationen mit nicht zugelassenen Gen-Konstrukten verursacht wurden. Die allenfalls geringen Kostenvorteile beim Anbau der Gen-Saaten rechnen sich auch in der Landwirtschaft nur kurzfristig.

Ch. Then & A. Lorch, Studie für den BÖLW März 2009.

On 31 Octobers, cottons fields were harvested in Texas, US. The cotton was then processed into cottonseed oil and cotton meal and sold as animal feed in the US and Mexico. Most of it might already been eaten up by now. One of the fields however was not a normal field but a field trial from Monsanto. A week after the harvest, scientists found that their experimental Bt cotton field had gone.

[img_assist|nid=222|title=|desc=|link=none|align=right|width=100|height=43]A growing demand for fuel is likely to lead to the development of genetically modified (GM) crops that can be used as commodities for agrofuels. Market pressure could lead to an acceptance of lower regulatory standards for their risk assessment and conditions for cultivation. Contamination of food and feed crops with non-edible GM agrofuel crops can threaten food safety and food security.

A. Lorch, Conference proceedings from Implications of GM-Crop Cultivation at Large Spatial Scales (GMLS), April 2008.

[img_assist|nid=247|title=|desc=|link=none|align=left|width=100|height=43]In 2007, the GM potato Amflora was cultivated on nearly 450 ha in Germany. The goal of the “field trial” as to produce seed potatoes just in case Amflora would be allowed for commercial cultivation. But another result now becomes quite obvious: GM potatoes cannot be kept under control and they cannot be cleared off the field completely. In summer 2008, despite repeated controls Amflora potatoes are happily growing on the field.

[img_assist|nid=239|title=|desc=|link=none|align=left|width=100|height=43]On 8 September, the EU Commission allowed the import of a new GM soy event that so far is mainly grown in the US. This does not only open the way for new GM soy in animal feed but it might also work as an incentive to allow its cultivation in South American countries because they now don't have to worry that soy contaminated with this event could not be exported to Europe.

[img_assist|nid=141|title=|desc=|link=none|align=left|width=99|height=43]Geen twee maanden nadat Greenpeace illegale contaminatie van maïs pellets in de haven van Rotterdam ontdekte, heeft de EU Commissie nu geprobeerd het probleem op te lossen, door de maïs Herculex RW (59122) als veevoer en voedingsmiddel toe te laten. De verantwoordelijke commissie ging er maandag niet mee akkoord.

In april is illegale contaminatie in maïs uit de VS in de havens van Rotterdam en Dublin gevonden: maïs voor veevoer was besmet met de gentech maïs Herculex RW (DAS-59122), die in de EU niet toegelaten is. Contaminatie met deze maïs is dus verboden - onafhankelijk ervan hoe groot deze contaminatie is.

Verrassend snel heeft nu de EU Commissie geprobeerd het probleem op te lossen: op maandag 25 Juni, geen 2 maanden nadat de Herculex RW ontdekt was, stelde de EU Commissie aan het verantwoordelijke comité (Permanent Comité voor de Voedselketen en de Diergezondheid) voor, deze maïs voor de import als veevoer en voedsel toe te laten. De aanvraag voor de import van Herculex RW als veevoer was, zo als aanvragen voor andere gentech-gewassen ook, al langer ingediend, maar dat de EU Commissie Herculex RW juist nu op de agenda zette, lijkt toch voor al met de aktuelle ontdekkingen te maken hebben. Als de import van Herculex RW toegestaan zoude zijn, dan zou contaminatie alleen nog een vraag van etikettering zijn en gecontamineerde maïs zou niet meer naar de VS teruggestuurd of vernietigd hoeven te worden.