The presence of recombinant DNA in soil cultivated with white poplars (Populus alba L.) expressing either the bar transgene for herbicide tolerance or the StSy transgene for resveratrol production, respectively, was investigated in a greenhouse over a 20-month period. The bar trial included the transgenic lines 5P56 and 6EA22P56 and the untransformed line, while the StSy trial was established with the transgenic lines 5EAC1 and 12EAC1 and with the untransformed line. All the transgenic poplars harbored the nptII marker gene. Plantlets were cultivated in pots, and soil samples were mixed in order to obtain composite pools which were used for molecular analyses. The 35SCaMV-bar (1504 bp), 35SCaMV-StSy (1403 bp) and NosP-nptII (1188 bp) sequences were detected in total DNA extracted from soil samples taken at different times after planting, using PCR/Southern blot hybridization. Microcosm experiments, carried out to assess the effects of temperature and DNA purity on transgene persistence, revealed only a partial correlation between the intensity of hybridization signals and the parameters tested.

We comment on Zaida Lentini's summary of Session V (titled “Estimating Likelihood and Exposure”) of the 9th International Symposium on the Biosafety of Genetically Modified Organisms. We provide an explanation of the drawbacks of using empirical pollen dispersion models, based largely on the general representativeness of the data used to generate the empirical models. We exemplify the drawbacks by highlighting the limited data used to develop the empirical model of Gustafson (presented in the same Symposium session). We provide a discussion of the meaning of “worst-case” assessments for pollen dispersion, how “worst-case” assumptions are commonly used in environmental impact assessments and how regulators will view worst-case impact assessments differently from the regulated (biotech) community. Finally, we clarify the advantages and disadvantages of mechanistic models and explain why they are often used in preference to empirical models in environmental impact assessments.

DiGiovanni and Kevan (2008, Environ. Biosafety Res.7: 105–108) commented extensively on the empirical approach that I and my co-authors took in our previous modeling of pollen-mediated gene flow in maize (Gustafson et al. (2006) Crop Sci.46: 2133–2140). As we detailed in that original paper, gene flow is a highly complex process that necessarily requires at least some level of empiricism in order to adequately quantify all of the biological, meteorological, and physical phenomena that are involved. DiGiovanni and Kevan favor a mechanistic modeling approach, and they proposed a number of potential advantages for such a method over our entirely empirical technique. However, the 20 m buffers we had proposed based on our empirical model continue to be supported by the rapidly growing body of experimental data on maize gene flow that has now been collected in Europe and elsewhere around the world. This does not mean there is no place for mechanistic modeling of gene flow, but it does suggest that properly implemented empirical approaches have a valid role to play. They offer a degree of simplicity and practical utility that is not available from more complicated approaches.


Biosafety regulatory frameworks are intended to serve as mechanisms for ensuring the safe use of biotechnology products without imposing unacceptable risk to human health or the environment, or unintended constraints to technology transfer. In several regulatory systems GMO risk assessment has been separated from GMO risk management. As a consequence, risk assessment can be performed on a purely scientific basis, whereas risk management can take additional aspects (e.g. socio-economic or ethical) into consideration. For instance, the European Food Safety Authority (EFSA), the keystone of European Union risk assessment regarding food and feed safety, provides independent scientific advice and clear communication on existing and emerging risks in close collaboration with national authorities and in open consultation with its stakeholders. Risk management measures are not within the remit of EFSA, and remain the responsibility of the European Commission and Member States.

The role of OECD in the development of national and international risk/safety assessment frameworks is presented and discussed. The most relevant OECD bodies in this context have contributed a lot to the development of international biosafety frameworks, inter alia by organizing international conferences in the areas of food/feed and environmental safety of GMOs, focusing on practical and current scientific issues. The OECD Consensus Documents as well as the OECD Product Database have provided a good basis for risk/safety assessment frameworks and their implementation. The relevance for the OECD work in the international area is discussed, in particular, with respect to the work undertaken under the Cartagena Protocol on Biosafety, the Codex Alimentarius Commission and its work in biotechnology, as well as under the International Plant Protection Convention. An outlook and suggestions for future directions of OECD work in this area are presented.

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Transgenic plants result from the isolation and insertion of genes into plants by means other than conventional breeding techniques, making it possible to isolate a gene that controls a valuable trait without also inserting thousands of other genes, as can occur with other methods. Transgenic plants potentially can provide substantial benefits to humans, but they can also pose risks to ecosystems, nontarget species and even to humans. I utilize the U.S. regulatory experience with chemical substances to provide some background for locating the strengths and weaknesses of different legal structures as well as providing an opportunity to learn from them. Learning from that case study and different legal structures utilized therein, as well as from the state of the world in which transgenic plants will be introduced and the state of the relevant sciences combined with a National Research Council Report on transgenic plants, this essay assesses the regulatory procedures that the U.S. Department of Agriculture uses to evaluate the risks from transgenic plants. These legal structures, although well suited for identifying risks before there is extensive exposure, have a number of shortcomings for reviewing the products of a new and not well-understood technology. The U.S. could take some steps toward improving its reasonable, tiered, pre-market approach for reviewing the risks from transgenic plants by following the NRC recommendations and learning from shortcomings of the regulation of chemical risks. Whether it will be or not remains to be seen.

Since the first regulatory approval of a genetically engineered (GE) plant was issued in 1992, hundreds of additional GE plants, thousands of regulatory decisions and millions of tons of GE grain and seed have been produced. In an increasingly global economy, the grain and seeds move relatively freely across national jurisdictions, but the regulatory decisions and associated data and analyses do not. Combined with the realities of agricultural production, this has led to a legal and regulatory challenge due to the low level presence (LLP) of GE grain or seeds that do not have regulatory approvals in the country of destination. In order to assist regulators in conducting environmental risk assessments related to LLP, reviews of environmental safety data, including associated regulatory analyses and decisions, for proteins commonly introduced in GE plants have been produced.