A review of available sources identified the following an LOC and acute toxicity data (LDLo, 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. Inhalation exposures were scaled to 60-minute equivalents using the ten Berge equation (Section 3.3.4). The most preferred species, a rat LC50, was selected as the TEEL-3. Although analysts considered the LOC (16.5 mg/m3) as a potential TEEL-2, they determined that 1) the resulting TEEL-2 would be considerably higher than the TEEL-3, and 2) LOCs are based on unspecified exposure limits from before 1987, which appear to have been discontinued for this chemical. Instead, TEEL-2 and TEEL-1 values were derived according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat LC50 (0.039 mg/L/4H)
This review generated a TEEL-3 source and value consistent with Rev. 29A. The Rev. 29A TEEL-2 was a dog oral TDLo not found during the review; instead, a TEEL-2 was derived from the TEEL-3 (Table. 3.5). The Rev. 29A and current TEEL-1 used the same methodology, with differences due to the change in TEEL-2.