Decision Document 2012-92
Determination of the Safety of Dow AgroSciences Canada Inc.'s
Corn (Zea mays L.) Event DAS-40278-9

This page is part of the Guidance Document Repository (GDR).

Looking for related documents?
Search for related documents in the Guidance Document Repository

This Decision Document has been prepared to explain the regulatory decision reached under Directive 94-08 (Dir94-08) - Assessment Criteria for Determining Environmental Safety of Plants with Novel Traits, its companion document BIO1994-11, The Biology of Zea mays L. (Maize), and Chapter 2.6 - Guidelines for the Assessment of Novel Feeds: Plant Sources of the Regulatory Guidance: Feed Registration Procedures and Labelling Standards.

The Canadian Food Inspection Agency (CFIA), specifically the Plant Biosafety Office of the Plant Health and Biosecurity Directorate, the Plant and Biotechnology Risk Assessment Unit of the Plant Health Science Directorate, and the Animal Feed Division of the Animal Health Directorate, has evaluated information submitted by Dow AgroSciences Canada Inc. This information is in regard to the herbicide-tolerant corn event DAS-40278-9. The CFIA has determined that this plant with a novel trait (PNT) does not present altered environmental risk nor, as a novel feed, does it present livestock feed safety concerns when compared to currently commercialized corn varieties in Canada.

Taking into account these evaluations, the unconfined release into the environment and use as livestock feed of corn event DAS-40278-9 is therefore authorized by the Plant Biosafety Office of the Plant Health and Biosecurity Directorate and the Animal Feed Division of the Animal Health Directorate as of October 5, 2012. Any corn lines derived from corn event DAS-40278-9 may also be released into the environment and used as livestock feed, provided that:

  1. no inter-specific crosses are performed;
  2. the intended uses are similar;
  3. it is known, based on characterization, that these plants do not display any additional novel traits and are substantially equivalent to currently grown corn in Canada, in terms of their potential environmental impact and livestock feed safety; and
  4. the novel genes are expressed at a level similar to that of the authorized line.

Additionally, with respect to its use as livestock feed, corn event DAS-40278-9 must meet the restrictions specific to 2,4-D and AOPP, or "fop," herbicide-treated feed set out in this authorization.

Corn event DAS-40278-9 is subject to the same phytosanitary import requirements as its unmodified counterpart. Corn event DAS-40278-9 is required to meet the requirements of other jurisdictions; including, but not limited to, the Food & Drugs Act, and the Pest Control Products Act.

The livestock feed and environmental safety assessments of novel feeds and PNTs are critical steps in the potential commercialization of these plant types. Other requirements, such as the evaluation of food safety by Health Canada, have been addressed separately from this review.

This bulletin is published by the Canadian Food Inspection Agency. For further information, please contact the Plant Biosafety Office or the Animal Feed Division at:

Plant Biosafety Office
Plant Health and Biosecurity Directorate
59 Camelot Drive
Ottawa ON K1A 0Y9
613-225-2342

Animal Feed Division
Animal Health Directorate
59 Camelot Drive
Ottawa ON K1A 0Y9
613-225-2342

Table of Contents

I. Brief Identification of the Modified Plant

II. Background Information

III. Description of the Novel Trait

  1. Development Method
  2. Tolerance to 2,4-D and AOPP (or "Fop") Herbicides
  3. Stable Integration into the Plant Genome

IV. Criteria for the Environmental Assessment

  1. Potential of Corn Event DAS-40278-9 to Become a Weed of Agriculture or be Invasive of Natural Habitats
  2. Potential for Gene Flow from Corn Event DAS-40278-9 to Sexually Compatible Plants Whose Hybrid Offspring May Become More Weedy of More Invasive
  3. Altered Plant Pest Potential of Corn Event DAS-40278-9
  4. Potential Impact of Corn Event DAS-40278-9 on Non-Target Organisms
  5. Potential Impact of Corn Event DAS-40278-9 on Biodiversity

V. Criteria for the Livestock Feed Assessment

  1. Potential Impact of corn event DAS-40278-9 on Livestock Nutrition
  2. Potential Impact of corn event DAS-40278-9 on Animal Health and Human Safety as it Relates to the Potential Transfer of Residues into Foods of Animal Origin, and Worker/Bystander Exposure to the Feed

VI. New Information Requirements

VII. Regulatory Decision

I. Brief Identification of the Modified Plant

Designation of the Modified Plant Corn event DAS-40278-9, OECD Unique Identifier DAS-4Ø278-9
Applicant Dow AgroSciences Canada Inc.
Plant Species Corn (Zea mays L.)
Novel Traits Tolerance to 2,4-D and "fop" herbicides
Trait Introduction Method Whiskers-mediated transformation
Intended Use of the Modified Plant Production of corn for human consumption (wet mill products, dry mill products, and seed oil) and oil, meal, grain, silage, and other byproducts for livestock feed. These plants are not intended to be grown outside the normal production area for corn in Canada.

II. Background Information

Dow AgroSciences Canada Inc. has developed a corn event that is tolerant to phenoxy auxin herbicides, such as 2,4-dichlorophenoxyacetic acid (2,4-D) and aryloxyphenoxypropionate (AOPP) acetyl coenzyme A carboxylase (ACCase) inhibitors (also known as "fop" herbicides). This corn event, designated DAS-40278-9, was developed to provide growers with an additional tool in managing weed populations.

Corn event DAS-40278-9 was developed by Dow AgroSciences Canada Inc., using whiskers-mediated transformation, resulting in the introduction of a synthetic version of the aad-1 gene from the bacterium Sphingobium herbicidovorans that was optimized for plant expression. Whisker-mediated transformation is a method that allows for the direct delivery of DNA into plant cells via silicon carbide whiskers (i.e. microfibers which measure 10-80 mm long and 0.6 mm wide). The vigorous agitation of a plant cell in the presence of whiskers results in the formation of micron-sized openings in the cell wall, thereby allowing entry of DNA into the cell. The inserted gene encodes the AAD-1 protein, which has alpha ketoglutarate-dependent dioxygenase activity, resulting in metabolic inactivation of the herbicides of the aryloxyalkanoate family.

Dow AgroSciences Canada Inc. has provided data on the identity of corn event DAS-40278-9, a detailed description of the transformation method, data and information on the insertion site, gene copy number, and levels of gene expression in the plant and the role of the inserted genes and regulatory sequences. The novel protein was identified and characterized. Data were provided for the evaluation of the potential toxicity of the novel protein to livestock and non-target organisms and potential allergenicity of the novel protein to humans and to livestock. Data were provided for the evaluation of herbicide residues in the feed commodities derived from the crop, following the intended herbicide application.

Corn event DAS-40278-9 was field tested in Canada and the United States in two different studies; one study comprising six sites and the other, 21 sites in the 2008 growing season. The locations of these trials share similar environmental and agronomic conditions to major corn production areas in Canada.

Agronomic characteristics of corn event DAS-40278-9, such as early population, seedling vigour, plant vigour and injury, time to silking, time to pollen, plant height, ear height, stalk lodging, root lodging, final population, days to maturity, stay green, grain moisture, test weight, and yield, were compared to those of the unmodified control.

Nutritional components of corn event DAS-40278-9, such as protein, fat, carbohydrates, fibre, ash, moisture, amino acids, fatty acids, vitamins, and anti-nutrients were compared with those of the unmodified control.

The Plant and Biotechnology Risk Assessment (PBRA) Unit of the Plant Health Science Directorate, CFIA, has reviewed the above information, in light of the assessment criteria for determining environmental safety of PNTs, as described in Directive 94-08 (Dir94-08) - Assessment Criteria for Determining Environmental Safety of Plants with Novel Traits.

The PBRA Unit has considered:

  • the potential of corn event DAS-40278-9 to become a weed of agriculture or to be invasive of natural habitats;
  • the potential for gene flow from corn event DAS-40278-9 to be sexually compatible plants whose hybrid offspring may become more weedy or more invasive;
  • the potential for corn event DAS-40278-9 to become a plant pest;
  • the potential impact of corn event DAS-40278-9 and its gene products on non-target species, including humans; and
  • the potential impact of corn event DAS-40278-9 on biodiversity.

The Animal Feed Division (AFD), of the Animal Health Directorate, CFIA, has also reviewed the above information with respect to the assessment criteria for determining the safety and efficacy of livestock feed, as described in Chapter 2.6 - Guidelines for the Assessment of Novel Feeds: Plant Sources of the Regulatory Guidance: Feed Registration Procedures and Labelling Standards.

The AFD has considered both intended and unintended effects and similarities and differences between the modified plant and its counterpart relative to the safety and efficacy of feed ingredients derived from corn event DAS-40278-9 for their intended purpose, including the potential impact of corn event DAS-40278-9 on:

  • livestock nutrition; and
  • animal health and human safety, as it relates to the potential transfer of residues into foods of animal origin, and worker and/or bystander exposure to the feed.

The AFD has also considered whether feeds derived from corn event DAS-40278-9 meet the definitions and requirements of feeds, listed in Schedule IV of the Feeds Regulations.

Dow AgroSciences Canada Inc. has provided the CFIA with a method for detecting and identifying corn event DAS-40278-9.

III. Description of the Novel Trait

1. Development Method

Corn event DAS-40278-9 was developed through whiskers-mediated transformation of corn embryo cells with a DNA fragment containing the aad-1 gene and its regulatory elements. Transformed cells were selected on the basis of tolerance to a "fop" herbicide and regenerated to produce plants. The presence of the aad-1 gene and its regulatory elements in the plants was verified by molecular methods.

2. Tolerance to 2,4-D and AOPP (or "Fop") Herbicides

Corn event DAS-40278-9 was developed to offer additional herbicide options, using 2,4-D and "fop" herbicides. The herbicide 2,4-D is a synthetic auxin, which disrupts new cell growth, thus inhibiting new growth in susceptible plants. "Fop" herbicides inhibit acetyl coenzyme A carboxylase, which contributes to lipid formation in roots, and hence causing death of susceptible plants. The AAD-1 protein, which was introduced into corn event DAS-40278-9, degrades 2,4-D into the herbicidal inactive 2,4-dichlorophenol (DCP). The AAD-1 protein also converts some "fop" herbicides into their corresponding inactive phenols. This type of metabolism is present in some plants but is unknown in conventional corn. Expression of AAD-1 in corn event DAS-40278-9 therefore enables the corn to grow in the presence of levels of 2,4-D and "fop" herbicides which are inhibitory to weeds.

AAD-1 expression in corn event DAS-40278-9 is driven by a constitutive promoter. Samples of corn event DAS-40278-9 tissues were collected from six field trial sites in the United States and Canada. Average AAD-1 expression levels, in micrograms protein per gram dry weight tissue (µg/g dwt), as evaluated by enzyme-linked immunosorbent assay (ELISA), ranged from 12.3 to 14.2 µg/g dwt in V2-V4 leaf, 5.38 to 6.52 µg/g dwt in V9 leaf, 5.57 to 6.06 µg/g dwt in R1 leaf, 2.87 to 3.92 µg/g dwt in R1 root, 6.84 to 7.32 µg/g dwt in R4 forage, 4.53 to 5.16 µg/g dwt in R6 whole plant, 4.61 to 5.00 µg/g dwt in grain, and 108 to 127 µg/g dwt in pollen.

To obtain sufficient quantities of AAD-1 protein for evaluation of environmental and feed safety, it was necessary to express the aad-1 gene in a microbial production system. The equivalency of the corn event DAS-40278-9-produced AAD-1 protein to the microbial-produced AAD-1 was evaluated by comparing their molecular weights, immunoreactivity, N-terminal sequence analysis, and MALDI-TOF mass spectrometry. Based on the results, the proteins were found to be equivalent.

Dow AgroSciences Canada Inc. provided an updated bioinformatics evaluation of the AAD-1 amino-acid sequence, which confirmed the lack of relevant similarities between the AAD-1 protein and known toxins and allergens. Further, the microbial AAD-1 protein did not cause any adverse effects in mice following a single oral dose of 2000 mg AAD-1 protein /kg body weight. Many allergens have been reported to be expressed at high levels in plants, be resistant to digestive enzymes and heat, and be glycosylated. The AAD-1 protein was expressed at low levels in corn event DAS-40278-9; in vitro digestive fate and heat-stability studies showed that the AAD-1 protein is rapidly degraded in simulated gastric fluid and is not heat-stable, and glycosylation was not detected on the DAS-40278-9-expressed AAD-1 protein. These results indicate that the AAD-1 protein in corn event DAS-40278-9 is unlikely to be a toxin or allergen.

3. Stable Integration into the Plant Genome

Molecular characterization by Southern blot analysis demonstrated that corn event DAS-40278-9 contains one intact copy of the aad-1 gene cassette inserted at a single site in the corn genome. No additional elements, including intact or partial DNA fragments of the aad-1 cassette or backbone sequences from the plasmid vector, linked or unlinked to the intact insert, were detected in corn event DAS-40278-9.

The stability of the insert within corn event DAS-40278-9 was verified by Southern blot analysis over five generations. The inheritance pattern of the aad-1 gene across six segregating generations of corn event DAS-40278-9 was evaluated by tolerance to a "fop" herbicide. The inheritance pattern of the herbicide tolerance trait showed that this trait segregated according to Mendelian rules of inheritance for a single genetic locus.

IV. Criteria for the Environmental Assessment

1. Potential of Corn Event DAS-40278-9 to Become a Weed of Agriculture or Invasive of Natural Habitats

The biology of corn, described in the CFIA biology document BIO1994-11 - The Biology of Zea mays L. (Maize), states that unmodified plants of this species are not invasive of unmanaged habitats in Canada. Corn does not possess the potential to become weedy, due to its lack of seed dormancy, the non-shattering nature of corn cobs, and the poor competitive ability of seedlings. Dow AgroSciences Canada Inc. provided data on phenotypic and agronomic traits to establish that corn event DAS-40278-9 is not weedier or more invasive than commercially available Canadian corn hybrids.

DAS-40278-9 hybrids were field tested in Canada and the United States in 2008 in two different studies; one study comprising six sites and the other 21 sites. An unmodified control consisting of a near-isoline that contained the same genetic background as DAS-40278-9, but without the novel trait, was also grown at each field location. Phenotypic and agronomic traits were evaluated, covering a broad range of characteristics that encompass the entire life cycle of the corn plant. The traits included the following: early population, seedling vigour, plant vigour and/or injury, time to silking, time to pollen, plant height, ear height, stalk lodging, root lodging, final population, days to maturity, stay green, grain moisture, test weight, and yield. Although instances of statistically significant differences were detected between DAS-40278-9 and the unmodified control, there were no consistent trends in the data across locations that would indicate that any of these differences were due to genetic modification. No significant difference was detected for any trait in the combined-site analysis.

In addition to the agronomic characteristics, susceptibility of corn event DAS-40278-9 to various corn pests and pathogens was evaluated. (Further detail is provided under item 3. Altered Plant Pest Potential of Corn Event DAS-40278-9.) No trend in increase or decrease of susceptibility was observed in corn event DAS-40278-9, compared to the unmodified control.

Dow AgroSciences Canada Inc. provided information on the germination of corn event DAS-40278-9 under a warm and a cool temperature regime. No significant differences were detected between DAS-40278-9 and the unmodified control for either temperature regime with respect to percent germination.

No competitive advantage was conferred to these plants, other than that conferred by tolerance to 2,4-D and the "fop" herbicides. Tolerance to these herbicides will not, in itself, render corn weedy or invasive of natural habitats, because none of the reproductive or growth characteristics were modified.

The CFIA considered the changes in usual agronomic practices that may arise from volunteer plants with novel herbicide tolerances, including tolerance to "fop" herbicides. Similarly, the CFIA considered the potential that continued application of the same herbicide in subsequent rotations may lead to increased selection pressure for herbicide-resistant weed populations. To address these issues, a herbicide stewardship plan that includes integrated pest management strategies should be implemented. These plans may include a recommendation to rotate or combine weed control products with alternate modes of action and to employ other weed control practices.

Dow AgroSciences Canada Inc. has submitted a Herbicide Tolerance Management (HTM) plan to the CFIA, evaluated by the PBRA. The HTM plan contains recommendations to address these concerns, as well as appropriate strategies that will allow for the environmentally safe and sustainable deployment of these traits. In addition, the HTM plan contains strategies for communication to growers and an efficient mechanism, allowing growers to report problems to Dow AgroSciences Canada Inc. Dow AgroSciences Canada Inc. will make this HTM plan readily available to growers to promote careful management practices for corn event DAS-40278-9.

The above considerations, together with the fact that the novel traits have no intended effects on corn weediness or invasiveness, led the CFIA to conclude that corn event DAS-40278-9 has no altered weed or invasiveness potential, compared to currently commercialized corn varieties.

2. Potential for Gene Flow from Corn Event DAS-40278-9 to Sexually Compatible Plants Whose Hybrid Offspring May Become More Weedy or More Invasive

Biology document BIO1994-11 - The Biology of Zea mays L. (Maize), indicates that there are no wild relatives in Canada that can hybridize with corn. This information, combined with the fact that the novel traits have no intended effects on corn reproductive biology, led the CFIA to conclude that there is minmal potential for gene flow from corn event DAS-40278-9 to related species in Canada.

3. Altered Plant Pest Potential of Corn Event DAS-40278-9

Corn is not considered a plant pest in Canada. The expression of the AAD-1 protein in corn event DAS-40278-9 is not expected to have effects on susceptibility to corn pests or pathogens.

The susceptibility of corn event DAS-40278-9 to various pests and pathogens was evaluated in the field at six sites in each of the 2009 and 2010 growing seasons. The stressors observed included leaf blights, gray leafspot, rust, eyespot, northern leaf blight, smut, aphids, grasshoppers, Japanese beetles, ground beetles, corn borer, corn ear worm, southwest cutworm, and yellow striped armyworm. Ecological evaluations of corn event DAS-40278-9 did not show any increase or decrease in susceptibility to any insect or disease stressor, compared to the unmodified control grown at the same locations.

The CFIA therefore concludes that corn event DAS-40278-9 does not display any altered pest potential, compared to conventional corn varieties.

4. Potential Impact of Corn Event DAS-40278-9 on Non-Target Organisms

The novel AAD-1 protein expressed in corn event DAS-40278-9 is naturally produced by Sphingobium herbicidovorans, a gram-negative soil bacterium which is widespread in the environment. Living organisms are therefore regularly exposed to S. herbicidovorans and its components, without known adverse consequences. In addition, the detailed characterization of the AAD-1 protein (as summarized in Part III Description of the Novel Traits) has led to the conclusion that this protein is not a putative toxin or mammalian allergen. Therefore, it is unlikely that the AAD-1 protein would be detrimental to organisms interacting with DAS-40278-9 corn plants.

An acute oral toxicity study with AAD-1 protein was conducted in mice at a level of 2000 mg/kg body weight. All animals survived, and no clinical signs were observed during the study.

Rapid degradation of the AAD-1 protein in simulated gastric fluid indicates a minimal likelihood that the protein could survive and be absorbed through the gastrointestinal system. Consequently, the AAD-1 protein would likely pose little risks to human and animal health.

A detailed compositional analysis showed that seeds and forage from DAS-40278-9 corn plants, which were either sprayed or unsprayed with 2,4-D and/or "fop" herbicides, contain similar levels of nutrients and anti-nutrients, compared with conventional corn varieties, indicating that the genetic modification has not caused an unintended change in the composition of DAS-40278-9 corn, relative to conventional corn.

Field evaluations showed no increase in resistance to insects or pathogens for corn event DAS-40278-9, compared with conventional corn hybrids. (Refer to item 3. Altered Plant Pest Potential of Corn Event DAS-40278-9.)

Collectively, these information elements indicate that no negative impacts on organisms resulting from exposure to corn event DAS-40278-9 are expected. The CFIA has therefore determined that the unconfined release of corn event DAS-40278-9 will not result in altered impacts on non-target organisms, including humans, compared to conventional corn varieties currently grown in Canada.

5. Potential Impact of Corn Event DAS-40278-9 on Biodiversity

Corn event DAS-40278-9 expresses no novel phenotypic characteristics that would extend its range beyond the current geographic range of corn production in Canada. Corn has no wild relatives with which it can outcross in Canada, and thus there will be no transfer of the novel traits to other species in unmanaged environments. As stated above, the novel traits are unlikely to have an impact on plant pest potential or non-target organisms. It is therefore unlikely that corn event DAS-40278-9 will have any direct effects on biodiversity, in comparison to the effects that would be expected from the cultivation of currently grown Canadian corn hybrids.

Corn event DAS-40278-9 has tolerance to 2,4-D and "fop" herbicides (although utilizing "fop" herbicides with this cropping system is not an intended use). The use of these herbicides in cropping systems has the intended effect of reducing local weed populations within agroecosystems. This may result in reductions in local weed species' biodiversity, and may have effects on other trophic levels which utilize these weed species. However, that the goal of reduction in weed biodiversity in agriculture fields is not unique to the use of PNTs and 2,4-D is one of the options currently used in conventional corn for control of broadleaf weeds. Therefore, corn event DAS-40278-9 will not have significant indirect effects on biodiversity, in contrast to the effects that would be expected from the cultivation of currently grown corn varieties.

The CFIA has concluded that the novel gene and its corresponding traits do not confer to corn event DAS-40278-9 any characteristic that would result in unintended environmental effects following unconfined release. The CFIA has therefore concluded that the potential impact on biodiversity of corn event DAS-40278-9 is unlikely to differ from that of conventional corn varieties grown in Canada.

V. Criteria for the Livestock Feed Assessment

The AFD considered nutrient and anti-nutrient profiles; the safety of feed ingredients derived from corn event DAS-40278-9, including the presence of gene products, residues, and metabolites in terms of animal health and human safety as it relates to the potential transfer of residues into foods of animal origin, and worker and/or bystander exposure to the feed; and whether feeds derived from corn event DAS-40278-9 meet the definitions and requirements of feeds, as listed in Schedule IV of the Feeds Regulations.

1. Potential Impact of Corn Event DAS-40278-9 on Livestock Nutrition

Nutrient and Anti-Nutrient Composition

The compositional equivalence of corn event DAS-40278-9 (unsprayed and sprayed with Quizalofop, 2,4-D, or Quizalofop + 2,4-D) to an unmodified control was determined from replicated trials at five sites in the United States and one site in Canada. Forage and grain samples were collected at each site and analyzed for proximate (crude fat, ash, protein, and moisture), acid detergent fibre (ADF), neutral detergent fibre (NDF), total dietary fibre (TDF), and minerals. Grain samples were further analyzed for amino acids, fatty acids, vitamins, secondary metabolites (inositol, coumaric acid, ferulic acid, and furfural) and anti-nutrients (phytic acid, trypsin inhibitor, and raffinose). No statistically significant differences were observed between corn event DAS-40278-9 forage and unmodified control for moisture, protein, ash, ADF, NDF, calcium, and phosphorus. Statistically significant differences were observed between corn event DAS-40278-9 (sprayed with Quizalofop) and the unmodified control forage for crude fat and carbohydrates; however, all means were within the range of published literature values of conventional corn varietiesFootnote 1 Footnote 2 and therefore the differences were not considered biologically relevant. No statistically significant differences were observed between corn event DAS-40278-9 grains and the unmodified control for moisture, fat, ash, ADF, NDF and TDF. Statistically significant differences were observed between corn event DAS-40278-9 (unsprayed and sprayed with Quizalofop and Quizalofop+2,4-D) and the unmodified control for protein and carbohydrates, but all means were within the range of published literature values of conventional corn varieties,Footnote 1 Footnote 2 and the differences were not biologically relevant. No statistically significant differences were found between corn event DAS-40278-9 grain and unmodified control for all minerals analyzed.

Except for arginine, glycine, lysine and tyrosine, small but statistically significant differences were found between corn event DAS-40278-9 grain and the unmodified control for the other amino acids. Mean values for all amino acids were, however, within the normal variation observed for conventional corn varieties. No statistically significant differences were observed between corn event DAS-40278-9 grain (sprayed or unsprayed) for palmitic, stearic, oleic, linoleic, linolenic, behenic, arachidic, and eicosenoic acids. Statistically significant differences were observed between corn event DAS-40278-9 (sprayed with Quizalofop and 2,4-D) and unmodified control grain for vitamin C and niacin, though all means reported for vitamins were similar to published literature values for conventional corn varieties.Footnote 1 Footnote 2 No statistically significant differences were observed between corn event DAS-40278-9 and unmodified control for coumaric acid, inositol, ferulic acid, and trypsin inhibitor, while statistically significant differences were found between corn event DAS-40278-9 (unsprayed) and the unmodified control for phytic acid. Means for phytic acid, were, however, within the range of published literature values for conventional corn varieties,Footnote 1 Footnote 2 and thus making the difference biologically irrelevant. Furfural and raffinose levels were below the level of quantification for both corn event DAS-40278-9 and the unmodified control grain.

Conclusion

Based on the evidence provided by Dow AgroSciences Canada Inc., the nutritional composition of corn event DAS-40278-9 is similar to conventional corn varieties.

2. Potential Impact of corn event DAS-40278-9 on Animal Health and Human Safety as it Relates to the Potential Transfer of Residues into Foods of Animal Origin, and Worker/Bystander Exposure to the Feed

Corn event DAS-40278-9 is tolerant to 2,4-D and "fop" herbicides, due to the production of the AAD-1 protein. The assessment of corn event DAS-40278-9 evaluated the impact of the following potential hazards that are relative to the safety of feed ingredients derived from this event:

  • presence of novel protein AAD-1
  • chemical pesticide residue profile

Novel AAD-1 protein

The AAD-1 protein is not a known toxin or allergen, and does not show sequence similarity to any known allergens or toxins, and lacks a mode of action that suggests it may be intrinsically toxic. The AAD-1 protein is also heat labile and rapidly degraded under conditions similar to those encountered in the gastrointestinal tract. No signs of toxicity were demonstrated in single-dose oral toxicity studies in mice, using purified microbial AAD-1 protein at 2000 mg/kg-bw. These factors support the lack of intrinsic toxicity or allergenicity of the AAD-1 protein.

Chemical pesticide residue profile

The safety of herbicide residues and metabolites in corn event DAS-40278-9 was not fully assessed, as there were no regulatory points of reference available at the time of the evaluation. The AFD has therefore placed a provisional restriction on feed commodities derived from corn event DAS-40278-9, following the application of 2,4-D or "fop" herbicides, until an authorization for 2,4-D or "fop" herbicides application on corn event DAS-40278-9 has been granted by Health Canada's Pest Management Regulatory Agency (PMRA).

Conclusions

Feed ingredients derived from corn event DAS-40278-9, without the application of 2,4-D or any "fop" herbicides, are considered to meet present ingredient definitions for corn and, as such, are approved for use as livestock feed in Canada.

VI. New Information Requirements

If at any time, Dow AgroSciences Canada Inc. becomes aware of any information regarding risk to the environment, including risk to human or animal health, which could result from release of corn event DAS-40278-9 in Canada or elsewhere, Dow AgroSciences Canada Inc. will immediately provide such information to the CFIA. On the basis of such new information, the CFIA will re-evaluate the potential impact of corn event DAS-40278-9 on the environment, livestock, and human health, and may re-evaluate its decision with respect to the livestock feed use and environmental release authorizations of corn event DAS-40278-9.

VII. Regulatory Decision

Based on the review of the data and information submitted by Dow AgroSciences Canada Inc. and other relevant information, the CFIA has determined that corn event DAS-40278-9 does not present altered environmental risk when compared to currently commercialized corn varieties in Canada.

Based on the review of submitted data and information by Dow AgroSciences Canada Inc., including comparisons of corn event DAS-40278-9 with its unmodified corn counterpart, the Animal Feed Division of the Animal Health Directorate, CFIA, has concluded that the novel AAD-1 protein-based herbicide tolerance trait will not confer to corn event DAS-40278-9 any characteristic that would raise any concerns regarding the safety or nutritional composition of corn event DAS-40278-9. Grain corn, its byproducts, and corn oil are listed in Schedule IV of the Feeds Regulations and are therefore approved for use in livestock feeds in Canada. Corn event DAS-40278-9 has been assessed and found safe as, and as nutritious as, traditional corn varieties. Corn event DAS-40278-9 and its products are considered to meet present ingredient definitions and are approved for use as livestock feed ingredients in Canada.

The safety of 2,4-D and "fop" residues in feed ingredients after 2,4-D and "fop" application to corn event DAS-40278-9 was not fully assessed. Any feed ingredient(s) derived from the combination of corn event DAS-40278-9 and 2,4-D or "fop" may not be manufactured or sold in Canada, or imported into Canada, until an authorization for 2,4-D or "fop" application on corn event DAS-40278-9 has been granted by Health Canada's PMRA.

Unconfined release into the environment and use as livestock feed of corn event DAS-40278-9 is therefore authorized by the Plant Biosafety Office of the Plant Health and Biosecurity Directorate and the Animal Feed Division of the Animal Health Directorate as of October 5, 2012. Any Zea mays lines derived from corn event DAS-40278-9 may also be released into the environment and used as livestock feed, provided that:

  1. no inter-specific crosses are performed;
  2. the intended uses are similar;
  3. it is known, based on characterization that these plants do not display any additional novel traits and are substantially equivalent to currently grown corn varieties in Canada in terms of their potential environmental impact and livestock feed safety; and
  4. the novel genes are expressed at levels similar to those in the authorized line.

In addition, with respect to its use as livestock feed, corn event DAS-40278-9 must meet the restrictions that are specific to 2,4-D and "fop" herbicide-treated feed set out in this authorization.

Corn event DAS-40278-9 is subject to the same phytosanitary import requirements as its unmodified counterpart. Corn event DAS-40278-9 is required to meet the requirements of other jurisdictions, including but not limited to, the Food and Drugs Act, and the Pest Control Products Act.

Please refer to Health Canada's Decisions on Novel Foods for a description of the food safety assessment of corn event DAS-40278-9.

Date modified: