A review of available sources identified several acute toxicity data (LD50, LCLo, LC50) for various species and routes, and exposure limits (OEL-STELs, OEL-TWAs). 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 60-minute equivalents using the ten Berge equation (Section 3.3.4). Two inhalation exposure toxicity data were evaluated for the TEEL-3 basis, a rat LCLo and mouse LC50; of these, the most preferred species data, the rat LCLo, was selected as the TEEL-3 basis. The TEEL-2 value was derived according to Table 3.5. The OEL-STEL (Austria, Denmark, Sweden) was selected as the TEEL-1.
• PAC-1 = TEEL-1 = OEL-STEL (Austria, Denmark, Sweden; 10 ppm/40 mg/m3)
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat LCLo (2000 ppm/4H)
This review generated PAC-3 and PAC-2 values consistent with Rev. 29A, and an inconsistent PAC-1 value. The Rev. 29A and current TEEL-3 and TEEL-2 values, sources, and methodology remain consistent. The Rev. 29A TEEL-1 was derived from the TEEL-2 (Table 3.5), while the current value is an exposure limit, OEL-STEL.