A review of available sources identified rat and mouse acute toxicity data (LD50, LC50) for various routes (oral, intraperitoneal, inhalation). 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 toxicity data, a rat LC50, was selected as the TEEL-3 basis and scaled to a 60-minute equivalent using the ten Berge equation (Section 3.3.4). TEEL-1 and TEEL- 2 values were derived according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat LC50 (1818 mg/m3/4H)
This review generated TEEL values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 basis was a rat oral LD50 while the current basis, a rat LC50, is a more preferred route. The Rev. 29A and current TEEL-2 and TEEL-1 bases and methodologies are consistent, with differences due to the change in TEEL-3.