A review of available sources identified multiple LD50 toxicity data 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. A high priority dog oral LD50 (22400 mg/kg) was evaluated for the TEEL-3 basis but resulted in a TEEL-3 value that was significantly less conservative than values derived from other available oral data; therefore, it was not selected for TEEL development. Instead, 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 (1700 mg/kg)
This review generated PAC values inconsistent with Rev. 29A. In Rev. 29A, the TEEL-3 basis was also a rat oral LD50; however, this review found and used data of a more conservative dose. The Rev. 29A and current TEEL-2 and TEEL-1 methodology remains consistent, with the difference in values due to the change of the TEEL-3 basis.