A review of available sources identified acute toxicity data (LD50) for various routes and species. Data sources were selected according to the hierarchy listed in Table 3.1. Toxicity data were selected according to type of exposure, species, and route according to the hierarchies stated in Sections 3.3.1, 3.3.2, and evaluated using factors in Tables 3.2, 3.3, and 3.4. The most preferred route and species toxicity data, a rat oral LD50, was selected as the TEEL-3 basis. TEEL-2 and TEEL-1 values were derived according to Table 3.5.
• PAC-1 = TEEL-1 = TEEL-2/11
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat oral LD50 (2000 mg/kg)
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 basis was a mouse intraperitoneal LD50; however, this review found and used an LD50 of more preferred species (rat > mouse) and route (oral > intraperitoneal). The Rev. 29A and current TEEL-2 and TEEL-1 use the same methodology, with differences due to the change in the TEEL-3.