Categories of Human Health Testing for EPA and FDA
Health-effects assessment (general testing for potential hazards)
Human safety assessment (more specific assessments)
Nonfood safety (only EPA)
To provide a cross section of recent activity under the general guidance that EPA informally provides to prospective registrants, the committee examined EPA pesticide fact sheets and data provided by the registrant for three registered Bt toxins that are regulated as plant-pesticides: Bt Cry3A delta endotoxin in potato (EPA 1995a), Bt subs. kurstaki Cry1Ac delta endotoxin in cotton (EPA 1995b), and Bt Cry1Ab delta endotoxin in corn (EPA 1997a and 1998a). The committee also reviewed EPA pesticide fact sheets for Bt subs. tolworthi Cry 9C protein in corn (EPA 1998c).
In general, oral toxicity testing for Bt endotoxins is based on the presumption that there is unlikely to be a problem inasmuch as a number of Bt toxins have been widely used for many years in microbial sprays without human toxicity. A variety of Bt proteins have been subjected to toxicological testing, starting with testing conducted on microbial Bt products, which typically contain multiple Bt proteins. This testing included acute, subchronic and chronic toxicology testing of products during the 1960s and 1970s (EPA 1988b; McClintock et al. 1995). However, it should be noted that most previous field uses resulted in minimal toxin ingestion by humans because sprayed microbial Bt toxin only remains effective for an average of 1.5 days (largely because of ultraviolet degradation), and therefore, residues are rare on fruits and vegetables. Also,