Document ID: EPA-HQ-OPP-2012-0109-0002
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2012-04-04T04:00Z

EPA BIOPESTICIDES AND POLLUTION PREVENTION DIVISION COMPANY NOTICE OF FILING FOR PESTICIDE PETITIONS PUBLISHED IN THE FEDERAL REGISTER 
	
EPA Biopesticides and Pollution Prevention Division contact:  Mike Mendelsohn, 703-308-8715, mike.mendelsohn@epa.gov

Syngenta Seeds, Inc.  -  Field Crops - NAFTA

[Insert petition number]

      EPA has received a pesticide petition ([insert petition number]) from Syngenta Seeds, Inc.  -  Field Crops  -  NAFTA, P.O. Box 12257, 3054 E. Cornwallis Road, Research Triangle Park, NC 27709-2257 proposing, pursuant to section 408(d) of the Federal Food, Drug, and Cosmetic Act (FFDCA), 21 U.S.C. 346a(d), to amend 40 CFR part 174.532

      1. NA-Remove
      2. NA-Remove
      3. to establish an amendment/expansion of an existing tolerance exemption for the
      
      1. NA-Remove
      2. NA-Remove
      3. plant-pesticide Bacillus thuringiensis eCry3.1Ab protein in or on corn.

      Pursuant to section 408(d)(2)(A)(i) of the FFDCA, as amended, Syngenta has submitted the following summary of information, data, and arguments in support of their pesticide petition. This summary was prepared by Syngenta and EPA has not fully evaluated the merits of the pesticide petition. The summary may have been edited by EPA if the terminology used was unclear, the summary contained extraneous material, or the summary unintentionally made the reader conclude that the findings reflected EPA's position and not the position of the petitioner.

I.  Syngenta Petition Summary
   
      [Insert petition number]

A. Product Name and Proposed Use Practices

      This notice of filing summarizes the information submitted and cited by Syngenta in support of a request for an exemption from the requirement of a tolerance for the Bacillus thuringiensis-derived eCry3.1Ab protein and the genetic material necessary for its production in corn.  The eCry3.1Ab protein is highly specific to the targeted coleopteran species, and is nontoxic to mammalian species. 
      
      Upon commercial introduction as a plant-incorporated protectant, eCry3.1Ab in corn will offer growers a new option for corn rootworm pest control and integrated pest management.

B. Product Identity/Chemistry

      1. Identity of the pesticide and corresponding residues.  The eCry3.1Ab protein has been incorporated into corn plants to provide control of corn rootworm pests.  It is a chimeric protein of modified Cry3A and Cry1Ab proteins derived from B. thuringiensis.  The ecry3.1Ab-transformed plants are derived from B. thuringiensis transformation event 5307, produced by Agrobacterium-mediated transformation.
      
      2. Magnitude of residues at the time of harvest and method used to determine the residue.  A determination of the magnitude of residues at harvest is not required for residues that are exempt from tolerances.

      3. A statement of why an analytical method of detecting and measuring the levels of the pesticide residue are not needed.  This petition is a request for an exemption from the requirement of a tolerance without numerical limitation, thus an analytical detection method should not be required.  However, in response to an Agency request the Petitioner has submitted an immunoassay method for determination of eCry3.1Ab protein in corn tissues.

C. Mammalian Toxicological Profile

      The eCry3.1Ab protein that is produced has an insecticidal mode-of-action that is well understood.  It is a chimeric protein of modified Cry3A and Cry1Ab proteins derived from B. thuringiensis.  B. thuringiensis proteins have been used as safe and effective pest control agents in microbial formulations for many years. The numerous toxicology studies conducted with these microbial products show no significant adverse effects and demonstrate that the products are nontoxic to mammals.  
      
      To be insecticidal, most known B. thuringiensis endotoxins must be ingested by the insect and solubilized in the gut, be activated by specific proteolytic cleavages, bind to specific receptors on the surface of the epithelial cells in the insect midgut, and form ion channels.  The completion of all four processes results in disruption of the normal function of the midgut leading to the death of the insect.  The eCry3.1Ab protein follows these similar steps in its toxicity to insects.  It has been demonstrated to display insect-specific toxicity following ingestion by sensitive coleopteran species.  The mode of action of eCry3.1Ab protein is highly specific to insects (Walters et al., Appl. Environ. Microbiol. 7:3082-3088, 2010).  This mode of action is not active in humans and other mammals as demonstrated in an acute mouse toxicology study wherein results confirmed that eCry3.1Ab protein is nontoxic to mice.  

      The eCry3.1Ab protein's species-specific mode of action, its similarity to B. thuringiensis proteins for which human safety has previously been established (e.g., Cry3A, Cry1Ab, and mCry3A), and the fact that it has been demonstrated that Cry proteins (Cry1Ab for example) do not damage the membrane integrity of mammalian intestinal epithelial cells and thus cannot exert adverse effects on the cell, all support the conclusion that no adverse health effects will result from exposure to the eCry3.1Ab protein.
      
     Single high dose oral exposure to eCry3.1Ab protein in mice produced no measurable adverse effects.  The eCry3.1Ab protein, produced in a heterologous fermentation system, was administered orally to male and female mice; a no observable effect level of > 2000 mg eCry3.1Ab/kg body weight was indicated.  No mortality or clinical signs attributable to the test substance were observed during the study.  The eCry3.1Ab protein is rapidly degraded upon exposure to simulated mammalian gastric fluid and heat, and shares no amino acid sequence similarity to proteins known to be mammalian toxins.  When proteins are toxic, they are known to act via acute mechanisms and at very low doses (Sjoblad, R. D. et al., Reg. Toxicol. Pharmacol. 15(1):3-9, 1992).  Therefore, when a protein displays no acute oral toxicity in high-dose testing using a standard laboratory mammalian test species, a determination can be made that the protein will be nontoxic to humans and other mammals, and will not present a hazard under any realistic exposure scenario, including long-term exposures.  In addition, a 49-day poultry feeding study demonstrated there were no adverse effects on broiler chickens consuming diets containing the eCry3.1Ab protein when compared with broiler chickens consuming control diets, with no eCry3.1Ab protein.  

      The eCry3.1Ab protein does not share significant amino acid sequence similarity to known protein allergens.  The eCry3.1Ab protein is not derived from a source organism known to produce allergenic proteins.  The source of the native Cry3A and Cry1Ab proteins is B. thuringiensis.  Bacteria have no history of allergenicity.  Additionally, despite decades of widespread use of B. thuringiensis insecticides on food crops, there have been no reports of oral allergies to these preparations, and laboratory animal studies submitted to the Agency have not shown any potential for allergic reactions to B. thuringiensis or its components.  No significant amino acid sequence similarities between eCry3.1Ab and known or putative allergenic protein sequences were identified.  Furthermore, the eCry3.1Ab protein was rapidly degraded in simulated mammalian gastric fluid and was inactivated and thus denatured when exposed to heat.  Based on this evidence, eCry3.1Ab protein is considered unlikely to be food allergen.  

     Collectively these data support a conclusion that eCry3.1Ab protein will be nontoxic to humans and is unlikely to be a food allergen.  There is reasonable certainty that no harm will result from mammalian (including human) exposure to the eCry3.1Ab protein.

D. Aggregate Exposure

      1. Dietary exposure.   Information is available to estimate aggregate exposure levels for consumers and major identifiable subgroups of consumers to the plant-incorporated protectant and related substances.

      i. Food. Oral exposure, at very low levels may occur from ingestion of corn and processed corn products; however, a lack of mammalian toxicity and the digestibility of eCry3.1Ab protein have been demonstrated.

      ii. Drinking Water Exposure.  Oral exposure, at very low levels, may occur through drinking water; however, a lack of mammalian toxicity and the digestibility of eCry3.1Ab protein have been demonstrated.  The use sites for eCry3.1Ab proteins are all agricultural for the control of insects.

      2. Non-dietary exposure. Exposure via the skin or inhalation is not likely since eCry3.1Ab protein is contained within plant cells, which essentially eliminates these exposure routes or reduces them to negligible levels.

E. Cumulative Effects

      There is no indication of mammalian toxicity potential for eCry3.1Ab protein.  The Cry1 and Cry3 classes of proteins display toxicity towards only a narrow spectrum of insect species.  It is reasonable to conclude that there will be no cumulative effects for this protein.

F. Safety Determination

      1. U.S. population. Based on available data for eCry3.1Ab protein there are no indications of mammalian toxicological effects and no threshold effects of concern.    Due to its digestibility, lack of toxicity and unlikely potential for allergenicity, eCry3.1Ab dietary exposure is not anticipated to pose any harm to the U.S. population.  There is no need for application of an additional safety factor for establishing an adequate margin of exposure.  Furthermore, special provisions pertaining to unique consumption patterns, special susceptibility, and cumulative effects do not apply.

      2. Infants and children.  Based on available data for eCry3.1Ab protein there are no indications of mammalian toxicological effects and no threshold effects of concern.    Due to its digestibility, lack of toxicity, and unlikely potential for allergenicity, eCry3.1Ab dietary exposure is not anticipated to pose any risk of harm to infants and children. There is no need for application of an additional safety factor for establishing an adequate margin of exposure.  Furthermore, special provisions pertaining to unique consumption patterns, special susceptibility, and cumulative effects do not apply.

G. Effects on the Immune and Endocrine Systems

      The available safety data for eCry3.1Ab protein show no adverse effects in mammals at high levels of exposure; thus, no effects on mammalian immune or endocrine systems are predicted.  Furthermore, the eCry3.1Ab protein is derived from B. thuringiensis and B. thuringiensis is known not to exert an influence on the endocrine system.

H. Existing Tolerances

      There is an existing temporary exemption (40 CFR §174.532) from the requirement of a tolerance for the B. thuringiensis eCry3.1Ab protein in or on corn which will expire on March 1, 2013.

I. International Tolerances

      No Codex maximum residue levels exist for B. thuringiensis eCry3.1Ab protein in plants.