A review of available sources did not identify acute toxicity data or exposure limits for phenol red, sodium salt. Instead, analysts evaluated rat and mouse intravenous LD50 acute toxicity data for a similar chemical, phenol red (CASRN: 143-74-8) for TEEL development (Section 3.4.6). 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 LD50 of the most preferred species, rat intravenous LD50, was selected as the TEEL-3 basis. TEEL-1 and TEEL-2 values were derived according to Table 3.5.
• PAC-1 = TEEL-1 = TEEL-2/11
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat intravenous LD50 (752 mg/kg; phenol red, CASRN: 143-74-8)
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 was based on an HHR=3, while the current value is based on rat intravenous LD50 toxicity data from a similar chemical (phenol red, CASRN: 143-74-8). The Rev. 29A and current TEEL-2 and TEEL-1 methodology remains consistent, with differences in values due to the change of the TEEL-3 basis.