Some considerations on the safety evaluation of nonviral microbial pesticides.

The tactics and rationale of maximum challenge safety tests for nonviral microbial pesticides have been reviewed. Maximum challenge tests and a tier approach to data collection for regulatory purposes offer the best opportunities to detect the acute effects of entomopathogenic organisms in mammals. Premature condemnation of promising organisms that are based on incomplete results of maximum challenge tests must be avoided. Further investigations should be conducted on the role of mammalian immune response in resistance to entomopathogenic organisms and on the value of medium- or long-term exposure tests.