A review of available sources identified acute toxicity data (LD50, LDLo, TDLo) for several species and routes. 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 species and route toxicity data, rat oral LD50, was selected as the TEEL-3 basis. The TDLo was evaluated as a TEEL-2 source, however it did not report toxicity endpoints applicable to TEEL development (i.e. weight loss) so it was not selected (Section 3.3.2). Instead, 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 (7 g/kg)
This review generated PAC-3 values consistent with Rev. 29A, and PAC-2 and PAC-1 values inconsistent with Rev. 29A. The Rev. 29A TEEL-2 basis was a mouse intraperitoneal TDLo that was evaluated but it was determined to have acute endpoints not appropriate for TEEL development; instead, the current TEEL-2 was derived from the TEEL-3 (Table 3.5). The Rev. 29A and current TEEL-1 use the same methodology, with differences due to the change in TEEL-2.