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Statement on Bt10

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EPA’s Regulatory Process and Evaluation of Bt10

EPA regulates pesticidal substances produced in plants and the genetic material necessary for the plant to make those substances. Under the Federal Insecticide, Fungicide, and Rodenticide Act, a compound is a pesticide if there is a claim that the substance will control a pest such as an insect, weed, or plant pathogen. EPA calls these pesticidal substances plant-incorporated protectants when they are intended to be used in the plant. EPA does not regulate such products when they are produced through conventional breeding techniques, but is regulating new substances such as those produced through modern biotechnology.

EPA also must make a determination about the safety of any pesticide residues in food or feed as required under the Federal Food, Drug, and Cosmetic Act (FFDCA). EPA’s authority is only with pesticides and the U.S. Food and Drug Administration has authority for other provisions of FFDCA.

EPA granted an exemption from tolerance for Bt Cry1Ab protein in all food and feed commodities on August 2, 1996. The tolerance exemption is published in the Code of Federal Regulations (40CFR 180.1173). In September 2001, EPA completed a reassessment of this tolerance exemption considering all of the existing data, public literature, and public comments. The reassessment determined that the tolerance exemption met all the scientific and regulatory standards. This tolerance exemption for the Bt Cry1Ab protein is not event-specific and therefore applies to all Cry1Ab protein including Bt10, Bt11, MON810, Event 176 and any other event producing the Cry1Ab protein that might be found in the food supply.

In order to be sold legally as food or feed in the United States, crops containing plant-incorporated protectants, such as the Bacillus thuringiensis (Bt) Cry1Ab protein produced by Bt10, must be covered by a tolerance or an exemption from tolerance issued by EPA under its FFDCA authority after completion of its safety review and a rulemaking process that allows for the public to comment and EPA to respond to any comments.

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EPA's Risk Assessment for Bt10 Plant-Incorporated Protectants

Syngenta performed the DNA sequence analysis of the genetic insert of the Bt10 event and submitted the sequence to the Agency. The coding sequences of the Bt10 event are identical to those previously reported for the registered event, Bt11. Syngenta provided data that all of the nucleotides in the coding region are identical in Bt10 and Bt11. The expressed proteins are Cry1Ab and the inert marker PAT for herbicide tolerance.

Syngenta also performed western blot analysis on the proteins expressed in leaf tissue from the Bt 10 event. The Cry1Ab and PAT proteins extracted from leaf tissue from the Bt10 event appear to be the same as the proteins from leaf tissue from Bt11 event based on the immunoreactivity of comigrating bands.

Syngenta submitted a published article comparing the Cry1Ab expression level in corn from event Bt10 compared with event Bt11, which showed that a hybrid produced from event Bt10 has much lower expression levels of Cry1Ab (< 1 ng/mg soluble protein) than hybrids produced from event Bt11 (257-457 ng/mg soluble protein). Lower expression levels of the Cry1Ab protein mean there is even a lower potential for possible adverse environmental effects on animals, birds, fish, and non-target insects.

Bt10 also has a marker gene for resistance to the antibiotic ampicillin that is not present in Bt11. The gene is under the control of a bacterial promoter and is not expected to be expressed in the corn so it does not need to be covered by any tolerance or tolerance exemption. According to information provided by Syngenta, the antibiotic resistance marker gene in Bt10 is the same as that in Event 176 corn.

40CFR 180.1173 - Bacillus thuringiensis CryIA(b) delta-endotoxin and the genetic material necessary for its production in all plants; exemption from requirement of a tolerance. Bacillus thuringiensis CryIA(b) delta-endotoxin and the genetic material necessary for its production in all plants are exempt from the requirement of a tolerance when used as plant pesticides in all plant raw agricultural commodities. “Genetic material necessary for its production” means the genetic material that comprise genetic material encoding the CryIA(b) delta-endotoxin and its regulatory regions. “Regulatory regions” are the genetic material that control the expression of the genetic material encoding the CryIA(b) delta-endotoxin, such as promoters, terminators, and enhancers. [61 FR 40343, Aug. 2, 1996]

40CFR 180.1151 - Phosphinothricin acetyltransferase (PAT) and the genetic material necessary for its production all plants; exemption from requirement of a tolerance. Phosphinothricin acetyltransferase (PAT) and the genetic material necessary for its production in all plants are exempt from the requirement of a tolerance when used as plant-pesticide inert ingredients in all plant raw agricultural commodities. “Genetic material necessary for its production” means the genetic material that comprise genetic material encoding the PAT protein and its regulatory regions. “Regulatory regions” are the genetic material that control the expression of the genetic material encoding the PAT protein, such as promoters, terminators, and enhancers. [62 FR 17719, Apr. 11, 1997].

For more information on FDA’s position on Bt10, see U. S. Food and Drug Administration’s Statement on Bt10.

Read more about the respective roles of USDA-APHIS, EPA, and FDA in the federal regulation of genetically engineered plants.

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