A review of available sources identified acute toxicity data (LD50, LCLo) for various species (rat, mouse, guinea pig) and routes (oral, 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. Inhalation exposures were scaled to 60-minute equivalents using the ten Berge equation (Section 3.3.4). The most preferred species and route data, a 4-hour rat LCLo, was selected as the TEEL-3 basis. The conservatism of the yielded value is supported by an NFPA rating=3, and GHS health hazard ratings (H317, H318, and H334; Category 1) that indicate a high-level hazard, approximately equivalent to an HHR=3. TEEL-1 and TEEL-2 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 (150 mg/m3/4H)
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 basis was a rat oral LD50, while the current basis is a rat LCLo, a more preferred data (LCLo > LD50) and exposure type (inhalation > oral). The Rev. 29A and current TEEL-2 and TEEL-1 methodology remains consistent, with differences in values due to the change of the TEEL-3 basis.