Replies by the Scientific Experts Advising the Panel
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WT/DS291/R/Add.6
WT/DS292/R/Add.6
WT/DS293/R/Add.6
Page H-245
ANNEX H
REPLIES BY THE SCIENTIFIC EXPERTS ADVISING THE PANEL
TO QUESTIONS POSED BY THE PANEL
GENERAL COMMENTS OF THE EXPERTS
Dr. Snow
A. Which environmental concerns about GM crops are really "science-based"?
1. A great deal has been written on this topic, and I will not try to summarize all of it here. Most hypothetical concerns pertaining to environmental effects of GM crops are included in the following list from the Ecological Society of America (Snow et al. 2005). Risk assessments are needed to minimize the likelihood of:
· creating new or more vigorous pests and pathogens;
· exacerbating the effects of existing pests through hybridization with related transgenic organisms;
· harming non-target species, such as soil organisms, non-pest insects, birds, and other flora and fauna;
· disrupting biotic communities, including agroecosystems;
· causing irreparable loss or changes in species diversity or genetic diversity within species.
2. Clearly, many GM crops are unlikely to cause any of these potential problems. Furthermore, it is not logical to group all GM crops into a single category and conclude that they are either inherently safe or inherently dangerous (see Question 103 below). It is important to evaluate new GM crops on a case-by-case basis in each country where the crop will be grown, and to do so using appropriate baseline comparisons. In the United States, for example, each new GM variety is compared to its non-GM predecessor in the context of conventional agricultural practices, and in the context of the nation's overall strategy for how its agricultural, environmental, and trade policies are implemented.
3. Some of the environmental concerns that EC Member States have raised in the documents are similar to concerns that routinely are addressed by regulatory agencies of the Complainants. However, there are also major differences in regulatory goals and policies. For example, the conservation of farmland biodiversity is a much bigger issue in Europe than in the USA or Canada (I am not familiar with the situation in Argentina). In some European countries, much of the non-urban landscape consists of farmland, which is the primary habitat for native insects, birds, and other animals. Also, EC Member States' strategies to manage and/or reduce herbicide applications differ from policies of the Complainants. In addition, the EC requires post-release monitoring to check for unanticipated environmental problems, reflecting a more cautious approach to risk assessment. The overall philosophy of EC Directive 2001/18 differs radically from regulations of the Complainants by emphasizing the possibility of cumulative and long-term hazards that could be caused by GM crops, and the need for precautionary decision-making to avoid irreversible harm to the environment. Ultimately, with regard to the Panel's questions about scientific issues, it may be useful to acknowledge these major differences between the disputing parties in their environmental and public health goals and their strategies for reaching these goals.
4. Some of the delays in EC regulatory decisions could be related to the time needed to develop new legislation that pertains to labeling (e.g., Regulation 1830/2003). Also, there were many requests for new information to be added to notifications when EC Directive 90/220, which had been in effect since 1990, was replaced by Directive 2001/18 in March 2001. The new Directive includes requirements for labeling and traceability, as well as consideration of socioeconomic and ethical issues.
5. Another question that has been raised in Europe is how to ensure that GM crops can "coexist" with non-GM crops, including both conventional and organic crops, such that current and future labeling standards can be met. I will not attempt to address this socioeconomic and legal issue, other than to note that scientific information about gene flow is often relevant to questions about coexistence. In some cases, further research may be needed to fill information gaps.
6. As a scientific advisor to the Panel, I am restricting my comments to over-arching questions about whether various Member States had valid reasons to conclude that additional scientific research was needed to complete their environmental risk assessments in 1998-2003.
7. Below, I list questions about possible environmental problems that could result from cultivating the specific GM crops that are cited in this dispute. These concerns apply mainly to agricultural landscapes rather than other managed or natural habitats for flora and fauna. For each new GM variety, one can ask whether its widespread cultivation is likely to cause any of the following outcomes to a greater degree than corresponding non-GM varieties:
a. create or exacerbate weed problems
b. cause direct or indirect harm to non-target species, including:
i. beneficial insects and soil organisms that affect crop yields
ii. native flora and fauna, including culturally important species
- e.g., native butterflies, skylarks, wild relatives of crop plants
c. lead to the use of more herbicides or insecticides, including more toxic ones, potentially harming flora, fauna, and human health.
Gene flow and the concept of "genetic pollution"
8. I will focus most of my comments on the environmental effects of gene flow from GM crops. In this context, the dispersal of transgenes by pollen or seeds is not a problem, in and of itself, unless this process has unwanted biological consequences. From this standpoint, the presence of transgenes in non-GM crops, wild relatives, or weeds can be seen as being part of a normal process that occurs with all crop genes. It is well known that crop genes can disperse widely by means of pollen and seeds. Only certain types of new genes, such as those that confer herbicide resistance or cause harm to non-target species, might lead to unwanted biological consequences.
9. The mere fact that GM crops are regulated may cause some people to conclude that all transgenes are risky. I do not agree with this opinion, as I discuss in my answer to Question 103. The process of artificially inserting genes into a plant's DNA can have unintended consequences, such as abnormal growth or development, but it is unlikely that 1) these effects will be ecologically significant in commercially-produced transgenic crops, or 2) they would be more risky than the types of side-effects that arise routinely during conventional breeding. In any case, many scientists agree that genetically modified plants should be judged on the basis of their phenotype – their actual characteristics – rather than the process that is used to develop them (e.g., Tiedje et al. 1989, NRC 2000, Snow 2003).
10. Moreover, there is no reason to expect that transgenes could be harmful simply because they are released in a particular crop's center of diversity (i.e., where many of the crop's wild ancestors or original cultivars occur; e.g., Gepts and Papa 2003, Bellon and Berthaud 2004). This topic has received a good deal of publicity, but there is no reason to expect that the effects of gene flow from modern cultivars on the genetic diversity of wild relatives differ between transgenic vs. nontransgenic crops. As stated above, gene flow does not represent an environmental concern per se, unless it results in unwanted biological consequences. If there are unwanted consequences, the extent to which the transgenes disperse via pollen and seeds may be analogous to the "exposure" term in the simple risk assessment equation "risk = exposure x harm", in which these terms are expressed as probabilities.
11. The documents in this dispute indicate that some Member States consider transgenes to be a type of genetic pollution, even though these genes are unlikely to have any negative effects on plants, animals, human health, or the environment. For example, Greece stated concerns about herbicide resistance transgenes from imported oilseed rape that is not intended for cultivation (see Question 66). Here the perceived risk appears to be that the transgenes would be harmful to native Brassica species. I do not agree that this would be a problem because 1) the imported seeds would not be cultivated (though some mix-ups with seed sources could occur), and 2) the transgene in question – a gene that confers resistance to the herbicide glufosinate – is unlikely to be harmful to native Brassica species in Greece, should they eventually hybridize with crop plants. Even if transgenic seeds of oilseed rape were to leak into the local farming system, perhaps establishing volunteer populations of oilseed rape, it is difficult to imagine how a transgene that confers resistance to glufosinate could be harmful to wild relatives of the crop.
B. Scientific uncertainty during 1998-2003
12. Biotechnology companies have been evaluating characteristics of GM crops for over two decades. As of 1998, however, the USA, Canada, and Argentina had only two years of experience with commercial-scale cultivation of transgenic Bt and herbicide-tolerant crops. Independent researchers who study environmental effects of GM crops had even less experience, partly because funding for this research was meager given the scope of key questions (e.g., Tiedje et al. 1989, Snow and Moran-Palma 1997, Snow 2002, Snow et al. 2005). Also, it has often been impossible for independent researchers to gain access to GM plants for field studies that precede deregulation (Dalton 2002). Rigorous ecological research typically requires several years and multiple teams of researchers to answer seemingly simple questions such as:
· Will pollen from Bt maize (corn) be harmful to native butterflies?
· Will volunteer plants from herbicide-tolerant oilseed rape become problematic weeds?
· How will farmland wildlife be affected by the cultivation of new GM crops as compared to current crops?
13. Therefore, from 1998-2003, many ecological questions about current and planned GM crops were just beginning to be addressed.
14. When additional scientific knowledge is needed to evaluate new GM crops, each nation's regulators and scientific advisory committees are placed in the difficult position of choosing between expediency and greater certainty. It is not always clear where the distinction lies between what regulators "need to know" vs. what is merely "nice to know". Regulators often have to rely on intuition or small-scale, unpublished studies, some of which lack adequate statistical tests (e.g. Marvier 2002). The routine, agronomic field trials that are conducted by biotech companies prior to deregulation are rarely intended to answer ecological-scale questions, nor would they be sufficient. Moreover, regulators and scientific advisory committees may not have the insight to correctly identify all of the potential risks that should be considered for each GM crop that is proposed for deregulation. In recent years, the hotly contested political, socio-economic, and ethical questions that pertain to GM crops have made it even more difficult to find the appropriate balance between expediency and certainty.
15. Scientific research can play an important role in how GM crops are evaluated by confirming or refuting widely held assumptions. Findings that are published in peer-reviewed scientific journals help define and answer key scientific questions that relate to risk assessments. Below, I include a sample of recent publications (1994-2003) that are relevant to this dispute because they illustrate recent discoveries. Several of these papers challenged widely held assumptions about pollen, gene flow, or herbicide-tolerant crops. The context for these papers should become clear in light of my answers to the questions from the Panel. Papers that appeared in four high-profile journals – Nature, Science, Philosophical Transactions of the Royal Society of London, and Proceedings of the US National Academy of Sciences – may have had the biggest impact on European decision-makers' perceptions about environmental effects of GM crops.
Examples of recent scientific findings about pollen, gene flow, and herbicide-tolerant crops:
(Listed in chronological order; see References for complete citations.)
1. Crop genes can spread from oilseed rape to populations of weedy Brassica rapa, contrary to previous expectations.
Jeorgensen and Andersen 1994. American Journal of Botany.
2. Transgenes that confer herbicide resistance can spread from oilseed rape to populations of weedy Brassica rapa (not surprising based on the paper listed above, although this article received a great deal of attention).
Mikkelsen et al. 1996. Nature.
3. Oilseed rape transgenes that confer herbicide resistance and spread to wild relatives do not harm weedy Brassica rapa, even in the absence of herbicide use.
Snow et al. 1998. Molecular Ecology.
4. Transgenic pollen from Bt maize is harmful to monarch butterfly larvae under laboratory conditions.
Losey et al. 1999. Nature.
In 2001, several follow-up papers in the Proceedings of the US National Academy of Sciences (e.g., Sears et al. 2001) concluded that this is not a problem under field conditions; in contrast, Jesse and Obrycki (2000; Oecologia) did find evidence for harmful effects on monarch butterfly larvae under field conditions.
5. Pollen flow among fields of herbicide-tolerant oilseed rape in Canada can lead to the emergence of weedy volunteer plants (from unharvested seeds) that are resistant to three types of herbicides.
Hall et al. 2000. Weed Science.
6. A modeling study showed that more effective control of weeds, for example in fields of herbicide-tolerant crops, could reduce the food supply of declining populations of skylarks in the UK.
Watkinson et al. 2000. Science.
7. Feral populations of oilseed rape can persist outside of cultivated fields for more than eight years, contrary to previous expectations. This study showed that persistent feral populations can originate from earlier varieties of the crop that are no longer planted.
Pessel et al. 2001. Theoretical and Applied Genetics.
8. Transgenes were discovered in locally produced landraces of maize in remote areas of Mexico, despite a national moratorium on planting transgenic maize.
Quist and Chapela. 2001. Nature.
(This finding was confirmed by further studies, while other conclusions in this controversial paper have largely been discounted.)
9. Unharvested and spilled oilseed rape seeds can acquire secondary seed dormancy and may persist for five years or longer in no-till as well as tilled systems, contrary to previous expectations. Previous studies suggested that seeds from the crop would be unlikely to acquire secondary seed dormancy under no-till conditions.
Simard et al. 2002. Weed Technology.
10. Pollen from oilseed rape fields can travel at least three kilometers away from source fields, thereby allowing cross-pollination to occur over much greater distances than previously expected.