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Professor Joe Cummins
The Animal and Plant Health Inspection Service (APHIS) of the US Department of Agriculture (USDA) received a petition 03-104-01p from Monsanto company and Scotts company on 14 April 2003 requesting deregulation of creeping bent grass genetically modified for tolerance to the herbicide glyphosate. On 5 January 2004, APHIS solicited public comments on whether the modified creeping bentgrass would present a plant pest risk. A preliminary environmental review was prepared by APHIS, and on 12 October 2005, APHIS requested additional information on APHIS Docket ID 03-101-4: Environmental Impact Statement; Petition for Deregulation of Genetically Engineered Glyphosate-Tolerant Creeping Bentgrass. Public comments are due by 14 November 2005: http://www.regulations.gov/fdmspublic-bld61/component/main
Roundup Ready creeping bent grass is tolerant to the herbicide glyphosate. It contains a gene conferring tolerance to the herbicide similar to Roundup Ready maize, soybean, canola, sugar beet or alfalfa. The resistance gene is a synthetic approximation of the 5-enolpyruvyshikimate-3 phosphate synthase from Agrobacterium sp. Strain CP4 (CP4EPSPS), which is preceded by the Arabidopsis chloroplast transit sequence which is required to direct the CP4ESPS to the chloroplast. Transcription is driven by the rice actin promoter and first intron, and terminated by nos 3 from Agrobacterium . A second identical CP4EPSPS sequence is driven by the CaMV promoter with duplicate enhancers, the heat shock 70 intron, and terminated by the nos3 sequence from Agrobacterium . Finally the insert contains nopaline antibiotic resistance gene. Duplicate copies of the herbicide tolerance gene ensure a high level of tolerance to glyphosate .
APHIS' preliminary risk assessment concluded that genetically modified (GM) creeping bent grass is phenotypicaly equivalent to unmodified grass. The GM grass had a single insert of the duplicate CP4EPSPS gene, which behaved as a simple Mendelian locus in crosses. The GM creeping bent grass does not differ in susceptibility or resistance to pests and diseases from its unmodified parent. However, the evidence was clear that hybrids with natural grass species were found and most of them were fertile. Herbicide tolerant creeping bent grass or its hybrids could be established in various urban to rural and natural areas .
APHIS asked The Weed Society of America, an industry-oriented academic organization, to evaluate the release of herbicide tolerant creeping bent grass in various crop and non-crop ecosystems. The report prepared on behalf of the society concluded that off-site movement of GM creeping bent grass was inevitable, but that the GM grass or its hybrids could be controlled using herbicides other than glyphosate . A study of gene flow from GM creeping bent grass showed that most of the gene flow occurred within 2 km of the field in which the GM grass was grown, but could extend to 14 and 24 km . Inter-specific hybridization between creeping bent grass and related grass species occurred at frequencies as high as six hybrids per thousand plants . Clippings from treated GM creeping bent grass stands were toxic to unmodified grasses, and such clippings will require special handling .
The impact of expanded urban and natural area use of glyphosate was hardly discussed in the petition for deregulation and environmental assessment, but that discussion was crucial and should have been included. Glyphosate is toxic to human placental cells within 18 hr at concentrations lower than recommended agricultural use, and Roundup more so than glyphosate. Surprisingly, Roundup was always more toxic than its active ingredient. The glyphosate-based herbicide disrupts aromatase activity and mRNA levels and interacts with the active site of the purified enzyme, and the effects of glyphosate are facilitated by the Roundup formulation in microsomes or in cell culture. The authors of the study conclude that endocrine and toxic effects of Roundup, not just glyphosate, can be observed in mammals . Relyea and his co-workers have documented the devastating impact of Roundup herbicide on amphibian communities in a series of reports [8-10]. Ho and Cummins have reviewed the problems associated with Roundup resistant weeds and the many human and animal health impacts including liver damage, cancers, neuro-defects and spontaneous abortion [11, 12].
The clear evidence of extensive gene flow and hybridization of glyphosate tolerant creeping bent grass, the growing problems of glyphosate resistant weeds plus the new evidence of glyphosate and Roundup toxicity to humans and lethality to amphibians should make any further release of glyphosate tolerant creeping bent grass out of the question, let alone its deregulation.
Article first published 07/11/05
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