A review of available sources identified acute toxicity data (LC50, LD50, LDLo) 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 route, a 7-hour rat LC50, was selected as the TEEL-3 basis and was scaled to 60-minute equivalent using the ten Berge equation (Section 3.3.4). TEEL-2 and TEEL-1 values were derived according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat LC50 (1 ppm/7H)
This review generated TEEL values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 basis was a dog intravenous LD50, while the current basis is a more preferred route (Table 3.1, LC50 > LD50). The Rev. 29A and current TEEL-2/TEEL-1 values were derived using the same methodology (Table 3.5), with differences due to the change in TEEL-3.