A review of available sources identified acute toxicity data (LD50, LDLo) for various routes and species, and exposure limits (OELs). 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 toxicity data, a rat oral LD50, was selected as the TEEL-3 basis. The TEEL-2 value was derived according to Table 3.5. The OELs were evaluated as TEEL-1 sources; however, they resulted in TEEL-1 > TEEL-2. Analysts evaluated the three sources for acute toxicity available, which resulted in TEEL-3 values ranging from 240-610 mg/m3. Considering this, analysts determined that the OELs may not be sufficiently conservative and instead derived the TEEL-1 according to Table 3.5.
• PAC-1 = TEEL-1 = TEEL-2/11
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat oral LD50 (2100 mg/kg)
This review generated PAC values consistent with Rev. 29A*.