The bucket and the searchlight: formulating and testing risk hypotheses about the weediness and invasiveness potential of transgenic crops

Abstract

The bucket and the searchlight are metaphors for opposing theories of the growth of scientific knowledge. The bucket theory proposes that knowledge is gained by observing the world without preconceptions, and that knowledge emerges from the accumulation of observations that support a hypothesis. There are many problems with this theory, the most serious of which is that it does not appear to offer a means to distinguish between the many hypotheses that could explain a particular set of observations. The searchlight theory proposes that preconceptions are unavoidable and that knowledge advances through the improvement of our preconceptions - our hypotheses - by continuous criticism and revision. A hypothesis is a searchlight that illuminates observations that test the hypothesis and reveal its flaws, and knowledge thereby increases through the elimination of false hypotheses. Research into the risks posed by the cultivation of transgenic crops often appears to apply the bucket theory; many data are produced, but knowledge of risk is not advanced. Application of the searchlight theory, whereby risk assessments test hypotheses that transgenic crops will not be harmful, seems to offer a better way to characterise risk. The effectiveness of an environmental risk assessment should not be measured by the size of the bucket of observations on a transgenic crop, but by the power of the risk hypothesis searchlights to clarify the risks that may arise from cultivation of that crop. These points are illustrated by examples of hypotheses that could be tested to assess the risks from transgenic crops and their hybrids becoming weeds or invading non-agricultural habitats.

Commercializing genetically modified crops under EU regulations

“…Ecotoxicology studies using plant material are increasingly required even when negligible ecological risk has been established through compositional analysis, 69 the mode of action of the transgenic protein, 61 and, in the case of insecticidal proteins, laboratory ecotoxicology studies that expose several representative surrogate species to high concentrations of the protein. 70 Additional exposure modeling is also required 71 even when conservative exposure scenarios reveal negligible risk to species highly sensitive to the insecticidal protein in question. 72 Additional studies that add little to our knowledge of risk impose costs on companies that must supply them and on regulators who must review them, without appreciable benefit to decision-making from those costs.…”

“…In reality, major changes were made even though few products had been approved for import and cultivation and no adverse effects detected. 74, 75 The changes seem to be driven more by political requirements to be seen to be tough on GM crops in response to public perception that GM crops are inherently harmful and pose greater risks than food-borne illnesses and inadequate diets. Chassy 76 summarizes the position pithily: "In spite of scientific analysis that indicates that transgenic crops are as safe as, or safer than, crops produced by other breeding modalities, transgenic plants are treated as if they were toxic chemicals or nuclear waste.…”

“…Decision-making can be postponed indefinitely by requiring further reductions in uncertainty; however, uncertainty is not the same as risk: just as one can never be certain that cultivation of a GM crop will never result in harm, 70 one can also never be certain that there will be no unforeseen benefits. Consequently, minimization of uncertainty cannot be the sole objective of regulation, even if the purpose of regulation is minimization of risk: if unrealized benefits are regarded as harm, delaying decisions while uncertainty is reduced may increase risk.…”

“…Definitions of harm should be set by social and environmental policy at the beginning of the risk assessment, and used to guide collection of relevant data that test hypotheses about the likelihood of those harmful effects occurring as a result of cultivating the GM crop. 70,90 And having defined the social and environmental policy objectives, political leadership should ensure timely regulatory decisions based on risk assessments, which estimate the likelihood that cultivation of the GM crop will meet those objectives.…”

Spread of volunteer and feral maize plants in Central Europe: recent data from Austria

“…Ecological harm in connection with a GMO includes that the transgenic crop produces seeds, which then disperse to non-agricultural habitats, that the crop establishes in the non-agricultural habitat and forms a self-sustaining population. If feral plants spread and thereby influence the abundance of native species, they will cause ecological harm [17–19]. It is often argued—because no visible ecological harm has been identified during the long history of cultivation of the conventional crop-type—that there would be no negative effect originating from the GM crop.…”