A review of available sources identified acute toxicity data (LD50, LDLo) for several species and routes. In addition, analysts evaluated cobalt (Co and inorganic compounds, CASRN: 7440-48-4, TLV-TWA) for TEEL development. 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 most preferred species and route toxicity data, a rat oral LD50, was selected as the TEEL-3 basis. The TEEL-2 value was derived according to Table 3.5. The TLV-TWA was selected as the TEEL-1 basis and a compound adjustment factor was applied (Section 3.2.2).
• TEEL-1 = MW-adjusted TLV-TWA (cobalt and inorganic compounds, CASRN: 7440-48-4; 0.02 mg/m3) x 3
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat oral LD50 (776 mg/kg)
This review generated TEEL-3 and TEEL-1 values consistent with Rev. 29A. The Rev. 29A and current TEEL-2 use the same methodology; therefore, minor differences in the TEEL-2 value may be due to rounding.