APHIS: Minimum Criteria for Non-Regulated Bt Corn 05-13-02 - Organic Trade Association
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APHIS: Minimum Criteria for Non-Regulated Bt Corn 05-13-02


Require A Non-Resistance Strategy and Evidence of Soil Ecological Health, and Ban the Use of Antibiotic Resistance Marker Genes, as Minimum Steps in Determining a Non-Regulated Status for Corn Genetically Engineered for Insect Resistance

Comments of the Organic Trade Association on APHIS Docket Number 00-078-1

Submitted by Tom Hutcheson,
 Associate Policy Director
April 10, 2002 

Insect-resistant plants will inevitably produce plant-resistant insects.  Bt plants have an intrinsic tendency to promote pest resistance because the Bt toxin is produced internally and generally, throughout the life of the Bt plant.  This means all Bt plants are inherently plant pests, as they will certainly, over time, diminish not only the effectiveness of external, specific applications of Bt, but also their own effectiveness.  This will lead to the loss of Bt as an insecticide.

In addition, soil ecology is certainly changed, and may be damaged, by Bt plant roots exuding the Bt toxin. Ecological studies have shown reason for concern regarding the use of Bt crops in general due to the persistence of the Bt toxin in soil as long as eight months after the crop is harvested.  This extended presence of the active insecticide, caused by root exudates, could affect soil ecology.[i]

The Organic Trade Association has commented to USDA, EPA, and FDA, that Bt crops are harmful in many ways to organic agriculture.  Organic agriculture uses ecological principles to produce food, but the ecology of Bt plants is rarely given independent, peer-reviewed study.[ii], [iii]

, when used with care not to stimulate insect resistance, is an excellent biological control for corn and cotton insect pests.  In fact, Bt is the most widely used biological control in organic agriculture.[iv]  The responsible use of Bt involves large, very short-term doses (typically with insect exposure of less than 48 hours).  On the other hand, the nature of bioengineered Bt plants is such that less effective doses are created over an entire growing season, resulting in a recipe for insect resistance.

So far, attempts to create a resistance strategy based on planting patterns have not resulted in an effective protocol.  This, combined with the lack of an enforcement program, signals that the use of bioengineered Bt plants will lead quickly to significant insect resistance, depriving organic farmers of one of their most useful biological pest controls.

Impending pest resistance to the common Cry1 protein is the reason Aventis developed Cry9 StarLink corn.[v]  EPA has, to its credit, expressed the current scientific consensus that the safety of the Cry9 protein in the human food chain is in serious doubt.

Just as there are serious questions about the anomalous expression of fusion genes,[vi] so must the common use of antibiotic resistance marker genes in Bt plants also be addressed as part of a plant pest assessment.  The British Medical Association has stated, “There should be a ban on the use of antibiotic resistance marker genes in GM food, as the risk to public health from antibiotic resistance developing in microorganisms is one of the major public health threats that will be faced in the 21st century.”[vii]  The American Medical Association has also expressed concerns:  “…the use of antibiotic markers that encode resistance to clinically important antibiotics should be avoided if possible.”[viii]

At the very least, USDA should enact a moratorium on support of Bt plants until an independently studied, peer-reviewed method for pest resistance management is ready to be implemented.  This could easily be extended to other Bt plants as well, and should be.  The few ecological studies that have been done to date show substantial reason for concern and should be sufficient to persuade APHIS to propose a moratorium on the commercial use of all Bt plants until independent, peer-reviewed studies have shown that there are no ecologically harmful effects.  These studies would have to provide compelling data on pest resistance; impacts on non-target species; pleiotropic effects; the stability of the transgenic line and the possibility of horizontal gene transfer;[ix] gene flow to wild relatives of corn, cotton, and all other crops for which a Bt form has been developed; and gene stacking.

One recent study has shown than Monarch butterfly larvae may usually be exposed in the field only to non-lethal doses of Bt corn pollen.  While good news for the Monarch, this information must also be interpreted as demonstrating the difficulty of implementing an effective insect resistance strategy due to the dispersal of Bt pollen in low doses.  Dispersal may become the primary mechanism for creating general insect resistance, at least among Lepidoterae for the Cry1 protein.

OTA also calls on APHIS to coordinate its work thoroughly with EPA, FDA, and NIH to ensure that the issues of human health, animal health, and environmental and ecological effects are considered comprehensively.  This new technology involves whole systems, and it is the responsibility of USDA, EPA, FDA, and NIH, at least, to ensure that no issues are left unconsidered.

Lastly, the use of Bt crops has an economic impact on organic production because pollen drift from Bt plants, leading to gene flow, can contaminate non-bioengineered organic crops.  Bt contamination is trespass, a nuisance, unwanted, and can lead to significant economic losses for organic farmers.  This is a clear example of potentially disastrous environmental degradation, with the added problem that consumers seeking products that contain no genetically engineered materials may be denied this choice because of inadvertent contamination.

[i]  Saxena, D., Flores, S., and Stotzky, G.  ( 1999).  Transgenic plants: Insecticidal toxin in root exudates from Bt corn.  Nature 402: 6761 (December 2, 1999), p. 480.

[ii]  A beginning to the ecological study of Bt corn may be found in Obrycki, et al.  (2001).  Transgeneic Insecticidal Corn:  Beyond Insecticidal Toxicity to Ecological Complexity.  BioScience, May, 2001.

Among other points APHIS may wish to note, the authors report that “Bt plantings are not being used as a replacement for insecticides but in addition to them.”

[iii]  Makhijani, A.  (2001).  Ecology and Genetics: An Essay on the Nature of Life and the Problem of Genetic Engineering.  Washington, DC.:  Institute for Energy and Environmental Research.

Makhijani writes in the summary document, “Creating new genomic structures by inter-species genetic engineering would be a very risky proposition under any circumstances, but it is particularly rash in the face of the fundamental gaps in knowledge of how genomic structures express themselves in ecosystems.”

[iv]  Walz, Erica.  (1999).  Final Results of the Third Biennial National Organic Farmers Survey.  Santa Cruz:  Organic Farming Research Foundation.  See p. 80.

[v]  Macintosh, Susan C.  (2001).  Unique Attributes of Cry9C (StarLink) Bt Help Assure Long-Term Viability of Bt in Crop Protection.  (Aventis white paper).  Web document:  http://www.us.cropscience.aventis.com/AventisUS/Cropscience/stage/html/whitepapersl.htm

Macintosh writes:  “A possible threat to Bt arises from the potential development of insect resistance to Bt. Now, a new Bt protein called Cry9C, marketed as StarLink, can be used to address those concerns because of its unique composition and characteristics.”

[vi] Leder, A., Pattengale, P.K., Kuo, A., Stewart, T.A., and Leder, P.  (1986).  Consequences of widespread deregulation of the c-myc gene in transgenic mice:  multiple neoplasms and normal development.  Cell, May 23, 1986, pp. 485-495.

[vii]  British Medical Association.  (1999).  The Impact of Genetic Modification on Agriculture, Food, and Health.  London:  Britich Medical Association.

[viii]  American Medical Association Council on Scientific Affairs.  (2001).  Genetically Modified Crops and Foods.  Chicago:  American Medical Association.

[ix]  Ho, M. W. et al.  (1998).  Microbial Ecology in Health and Disease 10, pp. 33-59; Ho, M.W., Ryan, A., Cummins, J.  (2000).  Microbial Ecology in Health and Disease 12, pp. 6-11; Ho, M.W., Steinbrecher, R.  (1998).  Environmental and Nutritional Interactions 2, pp. 51-84; Windels, P., et al.  (2001).  Eur Food Res Technol DOI 10.10007/s002170100336.


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