A review of available data sources identified the following: LD50 (mouse, rat,) toxicity data for oral 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 lowest available rat oral LD50, the most preferred species available, was selected as the TEEL-3 basis. TEEL-2 or TEEL-1 values were calculated from the TEEL-3 value, according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat oral LD50 (2700 mg/kg)
This review generated TEEL values which are inconsistent with those published in Rev. 29A. The TEEL-2 and TEEL-1 values are more conservative, while the TEEL-3 is less conservative than those reported in Rev. 29A. The TEEL-3 basis is consistent between the current and Rev. 29A basis (rat oral LD50,); however, the previous dose was not found in this review. A rat oral TDLo is referenced in Rev. 29A as the TEEL-2 basis. In this analysis, the toxic endpoints associated with this dose were deemed inappropriate for TEEL development (hepatocellular necrosis and enzyme inhibition). The TEEL-1 methodology is consistent, but as both were derived from differing TEEL-2s, this result also differed.