In the risk debate over genetically modified (GM) crops, their status as ''environmentally-friendly products'' has been controversial. The 1990 precautionary legislation of the European Union was designed to anticipate potential harm from GMOs in advance. Yet the acceptability of harm - or even its definition - has been contentious in evaluating commercial products. The legislation has been interpreted in ways which implicitly link concepts of precaution and ''sustainable development''. In the mid-1990s risk regulation, the European Union framed ''risk'' within a commitment to intensive agriculture. Its familiar hazards were accepted as a normal baseline for evaluating the effects of GM crops. The regulatory procedure regarded choices of crop protection measures as irrelevant or interchangeable, and therefore regarded some future options as dispensible, regardless of whether they would be environmentally preferable. At least implicitly, safety claims presupposed environmental advantages of GM crops in reducing agrochemical usage. That risk-framing came under challenge from widespread protest and expert disagreements. In response, some governments applied more precautionary measures. They broadened the definition of the ''adverse effects'' which must be avoided, devised market-stage precautions for such effects, and increased the burden of evidence for demonstrating safety. Soon the EU-wide procedure began to formalize such approaches. In the contested definitions of relevant harm, there are deeper issues about the sort of environment which should be protected, sustained or created. Thus GM crops have become a test case for environmental norms, within a broader debate about how to construct a sustainable agriculture.