A review of available sources identified acute toxicity data (LCLo, LD50) 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 and species, a 4-hour rat LCLo, was selected as the TEEL-3 basis and it was scaled to 60-minute equivalent using the ten Berge equation (Section 3.3.4). The acute dose is reported in µL/m3 therefore, it was converted using the density of this compound (1.173 at 25°C). 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 LCLo (2400 µL/m3/4H, converted to 2815 mg/m3/4H with density of 1.173 g/mL)
This review generated PAC values that are inconsistent with Rev. 29A. The Rev. 29A TEEL-3 basis was a rat oral LD50, while the current TEEL-3 basis is a rat LCLo, a more preferred route (inhalation > oral, Section 3.3.2). The Rev. 29A and current TEEL-2 and TEEL-1 use the same methodology, with differences due to the change in TEEL-3.