A review of available sources identified acute toxicity data (TDLo, LD50, LDLo) for several species and routes, and exposure limits (LOC, OEL-TWA). 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 species and route data, a dog oral LD50, was selected as the TEEL-3 basis. Although there were multiple human TDLo toxicity data, they were not selected for TEEL development due to long time durations and/or unspecified gender. The LOC was considered for the TEEL-2; however, it lacked conservatism relative to values derived from available LD50 data (dog, rat), therefore it was not selected. Instead, the TEEL-2 value was derived according to Table 3.5. The OEL-TWA (Poland) was selected as the TEEL-1 basis.
• PAC-1 = TEEL-1 = OEL-TWA (Poland; 0.0035 mg/m3) x 3
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Dog oral LD50 (30 mg/kg)
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 an oral LD50 of a more preferred species (dog > rat, Section 3.3.2). The Rev. 29A TEEL-2 was the LOC; however, the current TEEL-2 was derived from the TEEL-3 (Table 3.5). The Rev. 29A TEEL-1 was derived from the TEEL-2 (Table 3.5), while the current TEEL-1 basis is an exposure limit, OEL-TWA (Poland).