Microbial Bt products have been used as insecticides for more than 40 years without documented evidence of adverse effects. Additionally, a number of toxicological studies with insecticidal Cry proteins have not identified safety concerns with Bt proteins (McClintock et al., 1995 and EPA, 1998). But as genetically modified (GM) crops are becoming an increasingly important feature of agricultural landscapes. Several international organizations have developed guidelines to investigate safety of foods or feeds obtained from genetically modified plants to humans and livestock