The adoption of genetically modified (GM) crops in the European Union (EU) raises questions on the feasibility of coexistence between GM and non-GM crops. Regulations to ensure that different cropping systems can develop side-by-side without excluding any agricultural option are currently implemented or developed by member states. The aim of this review is to explore whether nationally or regionally proposed coexistence strategies comply with the general principles established by the European Commission that ask for science-based and proportionate coexistence measures. In the first part, existing legal requirements and potential sources of adventitious mixing are reviewed. It is discussed what type of coexistence measures might be necessary to keep GM inputs below the legal tolerance threshold of 0.9%. Concentrating on cross-fertilisation as the major biological source of adventitious mixing in maize, it is then assessed to which extent available scientific data on cross-fertilisation can explain the diversity of currently proposed isolation distances by several member states. In the second part, it is analysed whether currently proposed isolation distances reflect contending policy objectives towards GM crops that largely exceed the economic scope of coexistence. It is investigated how coexistence is intersecting with a wider debate about the role of GM crops in agriculture. Based on the analysis of existing cross-fertilisation data, it is concluded that some of the currently proposed isolation distances are not in line with the coexistence principles laid down by the European Commission: they are (i) excessive from a scientific point of view; (ii) difficult to implement in practice; (iii) rarely proportional to the regional heterogeneity in the agricultural landscape; and (iv) not proportional to the farmers’ basic economic incentives for coexistence. Hence, the range of proposed isolation distances cannot simply be explained by different interpretations of available scientific data, possible error intervals and remaining uncertainties inherent in the scientific process. It is argued that other than scientific issues must be at play. One might thus claim that coexistence has become an arena of contending values and visions on the future of agriculture and on the role GM crops might play therein.

中文翻译：

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欧盟的转基因和非转基因作物并存。回顾

欧盟（EU）采用转基因作物引发了人们对转基因作物与非转基因作物共存的可行性的质疑。成员国当前正在实施或制定法规，以确保不同的耕作制度可以并行发展而不排除任何农业选择。这次审查的目的是探讨国家或地区提出的共存战略是否符合欧洲委员会确立的要求基于科学和相称的共存措施的一般原则。在第一部分中，回顾了现有的法律要求和不规则混合的潜在来源。讨论了什么类型的共存措施可能需要使转基因投入保持在法律容忍度阈值0.9％以下。集中研究交叉施肥是玉米不规则混合的主要生物学来源，然后评估在何种程度上可获得的交叉施肥科学数据可以解释几个成员国目前提出的隔离距离的多样性。在第二部分中，分析了当前提议的隔离距离是否反映了对转基因作物的竞争政策目标，而这些目标大大超出了共存的经济范围。调查了共存与有关转基因作物在农业中作用的广泛辩论之间的交叉。根据对现有交叉施肥数据的分析，得出的结论是，当前提出的某些隔离距离与欧盟委员会制定的共存原则不符：（i）从科学的角度来看是过大的；（ii）难以在实践中实施；（iii）很少与农业景观中的区域异质性成比例；（iv）与农民共存的基本经济激励措施不成比例。因此，不能通过对现有科学数据的不同解释，可能的误差区间以及科学过程中固有的不确定性来简单地解释建议的隔离距离的范围。有人认为，除了科学问题外，还必须发挥作用。因此，人们可能会说，共存已经成为争夺关于农业未来以及转基因作物可能在其中发挥作用的价值观和远见的舞台。（iv）与农民共存的基本经济激励措施不成比例。因此，不能通过对现有科学数据的不同解释，可能的误差区间以及科学过程中固有的不确定性来简单地解释建议的隔离距离的范围。有人认为，除了科学问题外，还必须发挥作用。因此，人们可能会说，共存已经成为争夺关于农业未来以及转基因作物可能在其中发挥作用的价值观和远见的舞台。（iv）与农民共存的基本经济激励措施不成比例。因此，不能通过对现有科学数据的不同解释，可能的错误间隔以及科学过程中固有的剩余不确定性来简单地解释建议的隔离距离的范围。有人认为，除了科学问题外，还必须发挥作用。因此，人们可能会说，共存已经成为争夺关于农业未来以及转基因作物可能在其中发挥作用的价值观和远见的舞台。