A review of available sources identified an exposure limit (LOC) and acute toxicity data (LDLo, TDLo, 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 species data, a human (male) oral LDLo was selected as the TEEL-3 basis. A human (women) oral TDLo and LOC were evaluated for the TEEL-2 basis and yielded values similar in magnitude (3.7 mg/m3 and 5 mg/m3 respectively); as such, the most preferred data, LOC, was selected as the TEEL-2. The TEEL-1 value was derived according to Table 3.5.
• PAC-1 = TEEL-1 = TEEL-2/11
• PAC-2 = TEEL-2 = LOC (0.005 g/m3)
• PAC-3 = TEEL-3 = Human (male) oral LDLo (37 mg/kg)
This review generated a PAC-3 value inconsistent with Rev. 29A, and consistent PAC-2 and PAC-1 values. The Rev. 29A TEEL-3 was derived from the TEEL-2 (Table 3.5), while the current value is based on human (male) oral LDLo toxicity data. The Rev. 29A and current TEEL-2 and TEEL-1 values, sources, and methodology remain consistent.