Cost-benefit analysis studies on Bt

I was wondering if you could sign me up to be apart of the list serve.  In
addition,  I was wondering if there has been any cost-benefit analysis
studies done on genetically engineered crops -herbicide resistant crops and
pest resistant crops (Bt).  If so, could you please direct me to the
appropriate resources.

Madinah S. Ali
email: msa7@cornell.edu
Cornell University