A review of available sources identified the following exposures: LD50 (mouse, rat) for oral and intraperitoneal 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. Of the available rat LD50, there were female, male, and weanling doses reported. The lowest adult rat toxicity data (female) was selected as the TEEL-3 basis (Section 3.3.1). TEEL-1 and TEEL-2 estimates were calculated from this TEEL-3 value, according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Estimated from rat oral LD50 (1080 mg/kg)
This review generated TEEL values more conservative than Rev. 29A due to a different basis. The Rev. 29A TEEL-3 basis was the adult male rat toxicity data (1125 mg/kg), while the current recommendation is to use the adult female rat toxicity (1080 mg/kg), which is slightly lower and is justified according to Section 3.3.1: all else equal ”...the study with the lowest exposure concentration or dose is selected, yielding the more conservative TEEL value.”