Over 20 studies were analyzed to compare the expression profiles of
insecticidal proteins developed by commercial events in different
combinations of conventionally bred stacks. Results showed that many of the
tests analyzed had no significant increase in insecticidal protein
expression due to combination by conventional breeding. Most of the
variations observed in protein expression are likely caused by genetic and
environmental factors. Thus, all transgenic protein concentrations were all
within the conservative margins between exposure and corresponding
no-observed-effect-concentrations (NOEC).

The results of the study support the conclusion that protein expression data
generated from single events and the conservative manner for setting
non-target effects test concentrations allows for the transportability of
existing NOECs to the ecological risk assessment of conventionally bred
stacks.

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