This paper argues that risk assessment should be viewed as conforming to the model of the continuous development of scientific knowledge proposed by Karl Popper. As such, a risk assessment should begin with a problem and search for answers to that problem by testing hypotheses. Regarding a risk assessment as hypothesis testing recognises that safety cannot be proved, but can be indicated by tests of hypotheses that predict low risk. Confidence in the risk assessment is provided by the rigour with which the risk hypotheses are tested; it follows that testing should begin under conditions most likely to reveal that the risk hypothesis is false. If the risk hypothesis is corroborated under those conditions, there can be confidence that the risks posed by the genetically modified plant are low. Application of a criterion of increased rigour for hypothesis testing helps to establish whether requests for additional data are justified, and may reduce environmental risk by preventing undue delay in the registration of environmentally beneficial products.

KEYWORDS - Scientific method, problem formulation, hypothesis testing.