Novel Food Information - GlyTol Cotton Event GHB614
Health Canada has notified Bayer CropScience that it has no objection to the food use of GlyTol™ Cotton Event GHB614. The Department conducted a comprehensive assessment of this cotton event according to its Guidelines for the Safety Assessment of Novel Foods. These Guidelines are based upon internationally accepted principles for establishing the safety of foods with novel traits.
The following provides a summary of the notification from Bayer CropScience and the evaluation by Heath Canada and contains no confidential business information.
Bayer CropScience has developed a cotton event tolerance to glyphosate-containing herbicides. This event was developed through Agrobacterium-mediated transformation of Gossypium hirsutum variety Coker 312 to express a modified 5-enolpyruvylshikimate-3-phosphate synthase (2mEPSPS) which is tolerant to inhibition by glyphosate-containing herbicides.
The safety assessment performed by Food Directorate evaluators was conducted according to Health Canada's Guidelines for the Safety Assessment of Novel Foods. These Guidelines are based on harmonization efforts with other regulatory authorities and reflect international guidance documents in this area (e.g., Codex Alimentarius). The assessment considered: how GlyTol™ Cotton Event GHB614 was developed; how the composition and nutritional quality of this cotton line compared to conventional varieties; and the potential for this event to be toxic or cause allergic reactions. Bayer CropScience has provided data that demonstrate that GlyTol™ Cotton Event GHB614 is as safe and of the same nutritional quality as conventional cotton varieties used as food in Canada.
The Food Directorate has a legislated responsibility for pre-market assessment of novel foods and novel food ingredients as detailed in the Food and Drug Regulations (Division 28). GlyTol™ Cotton Event GHB614 is considered a novel food under the following part of the definition of a novel food:
- "c) a food that is derived from a plant, animal or microorganism that has been genetically modified such that
- (i) the plant, animal or microorganism exhibits characteristics that were not previously observed in that plant, animal or microorganism."
2. Development of the Modified Plant
The petitioner has provided information describing the methods used to develop GlyTol™ Cotton Event GHB614, in addition to the molecular biology data that characterize the genetic change, which results in the expression of the 2mEPSPS enzyme which is tolerant to glyphosate-containing herbicides.
GlyTol™ Cotton Event GHB614 was developed using Agrobacterium-mediated transformation of the G. hirsutum variety Coker 312 with the transformation plasmid pTEM2. The transforming plasmid carried a transfer DNA (T-DNA) sequence comprised of the 2mepsps gene and the regulatory components necessary for 2mEPSPS expression in cotton (i.e. the 2mEPSPS protein expression cassette). The double mutant 5-enolpyruvylshikimate-3-phosphate synthase gene (2mepsps) was isolated from corn (Zea mays) and modified to be insensitive to glyphosate inhibition. The wild-type corn epsps coding sequence was mutated using site-directed mutagenesis to create two point mutations that result in two amino acid changes in the enzyme.
3. Characterization of the Modified Plant
Southern blot analysis was used to determine the insert copy number, intactness of the 2mepsps coding region, intactness of the introduced T-DNA, and to confirm the absence of vector backbone sequences in GlyTol™ Cotton Event GHB614. This analysis demonstrated a single site of insertion of the pTEM2 T-DNA in the genome of GlyTol™ Cotton Event GHB614. This insertion is composed of a single intact copy of the 2mEPSPS protein expression cassette, including the 2mepsps gene and its respective regulatory sequences, the Ph4a748At promoter and 3' histonAt terminator. GlyTol™ Cotton Event GHB614 does not contain any of the backbone sequences from the transformation plasmid pTEM2.
In addition to Southern blot analysis, genomic DNA extracted from GlyTol™ Cotton Event GHB614 was subjected to polymerase chain reaction (PCR) analysis which verified the sequences at the 5' and 3' ends of the insert. PCR fragments of the left and right border regions were amplified and sequenced. Obtained sequence results showed that the sequence stopped within or immediately in front of the border regions. This supports the results of the plasmid backbone analysis that no sequences outside the border regions were integrated into the GlyTol™ Cotton Event genome
Generational stability of GlyTol™ Cotton Event GHB614 was determined over multiple generations in different genetic backgrounds, Southern blot analysis was performed using different generations of GlyTol™ Cotton Event GHB614 plants (self-crossed or crossed with conventional lines). Isolated DNA from leaf tissue was digested with the restriction enzyme EcoRV, which has one recognition site in the transforming DNA. The digested genomic DNA from GlyTol™ Cotton Event GHB614 was probed with a promoter T-DNA probe and showed the expected 5' and 3' integration fragments in all tested samples, thus showing the stability of the GlyTol™ Cotton Event GHB614 at the genomic level. Segregation data further confirmed the stability of the T-DNA insert, showing that it segregates as one dominant Mendelian locus.
4. Product information
GlyTol™ Cotton Event GHB614 differs from its unmodified counterpart by the addition of the 2mepsps coding sequence and the regulatory components necessary for 2mEPSPS expression in cotton. The insertion of the 2mepsps gene results in the expression of the 2mEPSPS protein: a modified 5-enolpyruvylshikimate-3-phosphate synthase which is tolerant to inhibition by glyphosate-containing herbicides.
5. Dietary Exposure
Cotton is the leading fibre crop with production in most of the tropical and subtropical agricultural regions of the world. Although lint is the most valuable product, in North America, cottonseed is also an important source of vegetable oil. Following ginning to remove the fibre, cottonseed is crushed to extract the oil. Cottonseed oil is used in cooking oil, shortening and salad dressing. Cottonseed oil is often an ingredient in snack foods such as crackers, cookies, and chips. Cottonseed meals and hulls are used in livestock, poultry, and fish feed.
Nine field trials were conducted in cotton growing southern US states in 2005. At each site, three plots (control, transgenic-unsprayed and sprayed) with three replicates were grown to collect cottonseed samples for laboratory analysis. The grain samples were analysed for: proximates, 18 amino acids, 6 minerals, complete fatty acid profile, cyclic fatty acids, vitamin E, phytic acid, and total and free gossypol. The results of the study showed that the level of analytes in cottonseed derived from GlyTol™ Cotton Event GHB614 were mostly comparable with its non-transgenic comparator. For the analytes where significant differences were observed, the values were within the literature range and the differences were considered not nutritionally relevant. Based on the nutrient data provided by the petitioner, it was concluded that GlyTol™ Cotton Event GHB614 is nutritionally comparable with its non-transgenic comparator.
The source of the 2mepsps gene used to generate GlyTol™ Cotton Event GHB614 is a plant (corn, Zea mays) with a long history of safe use as a food crop, and is not considered a significant source of toxins or allergens.
The novel protein present in GlyTol™ Cotton Event GHB614 is unlikely to be a toxin. The 2mEPSPS protein was not acutely toxic in mice at a dose that was orders of magnitude greater than the range associated with toxic proteins. The novel protein showed no significant amino acid sequence homology to any known toxin. It was also considered unlikely to be an allergen, since it showed no significant amino acid sequence homology to any known allergen. Further, the protein was assessed for potential epitopes and sites of glycosylation. The results found no known epitope sites and glycosylation was limited to two hypothetical sites. The protein was also degraded quickly in both simulated gastric and intestinal fluids, which suggests that the protein would be degraded in the human gastrointestinal tract and would be unlikely to enter the systemic circulation and elicit an allergic reaction. All of these studies suggest that the novel protein is unlikely to be an allergen.
The levels of endogenous toxins, gossypol and cylcopropenoid fatty acids, were not present in greater amounts in the novel plant than the conventional plant. For this reason, the levels of toxins present in the novel plant were not considered to present a greater risk to health than those present in the non-genetically modified plant. The modified cotton variety was not found to have increased levels of aflatoxins or heavy metals compared with the unmodified variety.
The levels of endogenous allergens were not directly addressed by the petitioner. However, the major food product, cottonseed oil, is a highly processed food commodity and contains negligible amounts of protein. Since most food allergens are proteins, this food product is not considered a risk for allergenic reactions.
A literature search examining more than fifty years of research, found only one case report of an allergy to ingested cottonseed flour which suggests that this allergy is uncommon. The protein profile of the novel cottonseed and its counterpart were not significantly different, which suggests that there are no changes in the amounts of various proteins, including allergens. Therefore it is unlikely that the cottonseed flour derived from the novel cottonseed would not contain more allergens than flour derived from its conventional counterpart.
It was concluded that the data presented in the submission suggest that food products derived from GlyTol™ Cotton Event GHB614 would not be associated with any greater risk to health than the cotton-derived food products already on the Canadian market.
Health Canada's review of the information presented in support of the food use of GlyTol™ Cotton Event GHB614 does not raise concerns related to food safety. Health Canada is of the opinion that food derived from GlyTol™ Cotton Event GHB614 is as safe and nutritious as food from current commercial cotton varieties.
Health Canada's opinion deals only with the food use of GlyTol™ Cotton Event GHB614. Issues related to its use as animal feed have been addressed separately through existing regulatory processes in the Canadian Food Inspection Agency (CFIA). The CFIA evaluated information provided on the environmental, animal, and human health safety of GlyTol™ Cotton Event GHB614 with the intended use in animal feed. From their assessment, the CFIA concluded that there are no concerns from an environmental and feed safety perspective. This perspective is applicable to the food and feed products derived from GlyTol™ Cotton Event GHB614 destined for commercial sale.
It is the continuing responsibility of the food manufacturer or importer to ensure that their products are in compliance with all applicable statutory and regulatory requirements. Any new information obtained in relation to these products which have potential health and safety implications should be forwarded to Health Canada for our consideration in order to ensure the continued safety and integrity of all foods available in the Canadian marketplace. The sale of a food which poses a hazard to the health of consumers would contravene the provisions of the Food and Drugs Act.
This Novel Food Information document has been prepared to summarize the opinion regarding the subject product provided by the Food Directorate, Health Products and Food Branch, Health Canada. This opinion is based upon the comprehensive review of information submitted by the petitioner according to the Guidelines for the Safety Assessment of Novel Foods.
(Également disponible en français)
For further information, please contact:
Novel Foods Section
Health Products and Food Branch
Health Canada, PL2204E
251 Frederick Banting Driveway
Ottawa, Ontario K1A 0K9
- Date modified: