EPA reviews data on the rate of degradation of the pesticidal protein in plant tissue in the soil. EPA considers whether the introduced pesticidal substance is toxic to wildlife, beneficial insects, fish, or other organisms and, if so, whether those organisms will be exposed to the protein. For example, Bt proteins have been tested at doses typically 10 to 100 times the expected exposure from the pesticidal plant. The tests are carried out with a range of non-target insects such as honeybees, green lacewing, ladybird beetles, and parasitic wasps, and with other organisms such as earthworms, fish, birds and rodents. In addition to data requirements for pesticide registration, EPA must review all animal and human dietary risks of the pest control protein to determine whether a tolerance limit should be set on the amount of protein in food derived from the improved plant.
Public comment is invited.
If there is already substantial data on the safety of the protein and a history of safe use, the developer may request an exemption from the tolerance requirement. Such exemptions are not automatically granted. In addition, EPA can impose new measures as new information becomes available. For example, for purposes of insect resistance management, beginning in the 2000 crop year, growers must plant an area of non-Bt corn equal to 20 percent of their acreage, along with their Bt corn seeds. For Bt corn grown in cotton areas, farmers must plant at least 50 percent non-Bt corn.