關於Bt，美國科學院的報告裏專門說了一下。

Regulatory Testing of Crops Containing Bt Toxins

EPA considers plant-produced  Bt toxins to be “plant-incorporated protectants,” a class of

products generally defined as “a pesticidal substance that is intended to be produced and used in a living

plant, or in the produce thereof, and the genetic material necessary for the production of that pesticidal

substance” (40 CFR §174.3). EPA specifically exempts plant-incorporated protectants whose genetic

material codes for a pesticidal substance that is derived from plants that are sexually compatible.

 

Bt toxin genes are not exempted because they come from bacteria (see Chapter 9 for regulatory details).

For Bt toxins produced by GE crops, EPA took into consideration that there was already toxicity

testing of  Bt toxins in microbial pesticides and that the toxins were proteins that, if toxic, typically show

almost immediate toxicity at low doses (EPA, 2001a; also see Box 5-2). The pesticidal safety tests mostly

involved acute toxicity testing in mice and digestibility studies in simulated gastric fluids because one

characteristic of food allergens is that they are not rapidly digested by such fluids.

Box 5-2 provides a verbatim example of the procedures used for testing as reported in EPA fact

sheets for the Cry1F

 

Bt toxin so that readers can see what is involved in the testing. The actual research is

not typically done by EPA itself. The registrant is usually responsible for testing. Results of the tests of

Cry1F show no clinical signs of any toxicity even when Cry1F protein was fed at 576 mg/kg body weight,

which would be the equivalent of about ¼ cup of pure Cry1F for a 90.7-kilogram person. Another part of

the testing described in Box 5-2 is allergenicity testing. Concerns about the EPA testing methods are

discussed in sections below on each category of testing.