A review of available sources identified the following: LD50 and LDLo acute toxicity data for oral and intravenous 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. GHS health hazard data indicates corrosive hazards (H318/Category 1 and H315/Category 2) and acute toxicity (H302/Category 4), corresponding to an HHR=3 (TEEL-3=79 mg/m3) and HHR=2 (TEEL-3=790 mg/m3), respectively. The most preferred route and species toxicity data, an oral rat LD50, was selected as the TEEL-3 basis. This LD50 was reported as a large range (681-1470 mg/kg); therefore, the lower limit was evaluated for conservatism. 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 oral LD50 (681 mg/kg)
This review generated TEEL values that are inconsistent with Rev 29A. The Rev. 29A TEEL-3 basis was a rat intravenous LDLo, while the current basis is a rat oral LD50, a more preferred source (Table 3.1). The current TEEL values are in a magnitude consistent with analysis from reported GHS health hazard data.