Assessing environmental risks of transgenic plants

Abstract

By the end of the 1980s, a broad consensus had developed that there were potential environmental risks of transgenic plants requiring assessment and that this assessment must be done on a case-by-case basis, taking into account the transgene, recipient organism, intended environment of release, and the frequency and scale of the intended introduction. Since 1990, there have been gradual but substantial changes in the environmental risk assessment process. In this review, we focus on changes in the assessment of risks associated with non-target species and biodiversity, gene flow, and the evolution of resistance. Non-target risk assessment now focuses on risks of transgenic plants to the intended local environment of release. Measurements of gene flow indicate that it occurs at higher rates than believed in the early 1990s, mathematical theory is beginning to clarify expectations of risks associated with gene flow, and management methods are being developed to reduce gene flow and possibly mitigate its effects. Insect pest resistance risks are now managed using a high-dose/refuge or a refuge-only strategy, and the present research focuses on monitoring for resistance and encouraging compliance to requirements. We synthesize previous models for tiering risk assessment and propose a general model for tiering. Future transgenic crops are likely to pose greater challenges for risk assessment, and meeting these challenges will be crucial in developing a scientifically coherent risk assessment framework. Scientific understanding of the factors affecting environmental risk is still nascent, and environmental scientists need to help improve environmental risk assessment.

Nutritionally Enhanced Staple Food Crops

“…The environmental risks associated with the GM crops such as gene flow, adverse effects on biodiversity and on the beneficial insects, and the potential emergence of superweeds are not referred to here as these issues have been adequately dealt elsewhere (Wolfenbarger and Phifer 2000;Andow and Zwahlen 2006;Kwaku and Asante 2008;Dunfield and Germida 2010;Hokanson et al 2010;Jiang et al 2010;Liu 2010;Raybould et al 2010).…”

Assessing the effects of cultivating genetically modified glyphosate-tolerant varieties of soybeans (Glycine max(L.) Merr.) on populations of field arthropods

“…Because small-scale field experiments such as the present study (with a limited number of sites, a short term of only two years, and a relatively small field) are not sufficiently sensitive to detect anything but obvious local ecological effects, more large-scale and long-term assessments are needed (Andow and Zwahlen, 2006). As suggested, soil organisms may take a long time to respond to a new GMHT cropping regime.…”

A screening method for prioritizing non-target invertebrates for improved biosafety testing of transgenic crops

“…A "risk endpoint" (i.e., possible adverse effect) is then defined for each functional group and the species within each are prioritized "in relation to the likelihood of the risk endpoint associated with the functional group" using "a series of qualitative ecological characteristics" , including association with the crop and functional significance of the species in the cropping system (Hilbeck et al, 2006). These ranked lists allow identification of the species "most likely to cause concern" based on historical local knowledge of their significance, and their degree of association with the crop and the transgene product (Andow and Zwahlen, 2006). Several top-ranked species are then selected from each list as subjects for testing specific risk hypotheses (Andow and Zwahlen, 2006;Hilbeck et al, 2006).…”

“…These ranked lists allow identification of the species "most likely to cause concern" based on historical local knowledge of their significance, and their degree of association with the crop and the transgene product (Andow and Zwahlen, 2006). Several top-ranked species are then selected from each list as subjects for testing specific risk hypotheses (Andow and Zwahlen, 2006;Hilbeck et al, 2006). While this method produces useful, workable lists of potential endpoints, it is likely that automation of this type of selection system would greatly increase the speed and repeatability of the problem formulation process.…”