A review of available sources identified toxicity data (LDLo, LC50, LD50) for various 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 data of the most preferred route and species, a rat LC50, was selected as the TEEL-3 basis and was scaled to a 60-minute equivalent using the ten Berge equation (Section 3.3.4). TEEL-1 and TEEL-2 values were derived according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat LC50 (1.6 mg/L/4H => 1600 mg/m3/4H)
This review generated TEEL values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 was also based on rat toxicity data, however this review used a more preferred data type (LC50 > LDLo) and route (inhalation > oral). The TEEL-2 and TEEL-1 methodology remain consistent, with the difference in values due to the change in the TEEL-3 basis.