A review of available sources identified exposure limits (STELs, TWAs) and acute toxicity data (LCLo, 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. Inhalation exposures were scaled to a 60-minute equivalent using the ten Berge equation (Section 3.3.4). The human oral LDLo was evaluated but it did not report the sex of the subject, so it was not selected for TEEL development. The LCLo was evaluated; the resultant TEEL-3 was less than short term exposure limits (TEEL-3 < TEEL-1) so it was not selected. Instead, analyst selected the most preferred species toxicity data, a dog intravenous LDLo, was selected as the TEEL-3 basis. The TEEL-2 as derived according to Table 3.5. The TLV-STEL was selected as the TEEL-1.
• PAC-1 = TEEL-1 = TLV-STEL (20 ppm, 90 mg/m3)
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Dog intravenous LDLo (700 mg/kg)
This review generated PAC values consistent with Rev. 29A*.