A review of available sources identified the following: rat LCLo and LDLo acute toxicity data. Data sources were selected according to the hierarchy listed in Table 3.1. Toxicity data were selected according to type of exposure 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 GHS inhalation hazard ratings were also evaluated to estimate an appropriate magnitude for the TEEL-3; from PubChem, ECHA reports a GHS inhalation hazard of at least 3, indicating the TEEL magnitude should range between and HHR of 2 and 3, or TEEL-3 between 79 and 790 mg/m3. The most preferred route and species, the rat LCLo, was selected as the TEEL-3 basis and scaled to 60-minute equivalent using the ten Berge equation (Section 3.3.4). This TEEL-3 is also consistent with the expected magnitude, based on reported GHS inhalation hazards. TEEL-2 and TEEL-1 values were calculated according to Table 3.5.
• TEEL-1 = TEEL-2/11
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat LCLo (2000 ppm/4H)
This review generated TEELs value less conservative that those reported in Rev. 29A. The Rev. 29A TEEL-3 basis was a rat intraperitoneal LDLo, which is a less preferred route than the current basis (LCLo> LDLo). The Rev. 29A and current TEEL-2 and TEEL-1 methodology are consistent, with differences due to the change in TEEL-3.