A review of available sources identified the following: acute toxicity data for tellurium oxide and exposure limits for tellurium (CASRN: 13494-80-9, TLV-TWA, IDLH). 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 rat oral LD50 was evaluated but was found to result in a TEEL value that was approximately 20x the IDLH for tellurium, indicating it was not conservative enough. Instead, the tellurium effective IDLH (1990) was selected as the TEEL-3 basis and a compound adjustment factor was applied (Section 3.2.2). TEEL-2 values were derived according to Table 3.5. The tellurium 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 (tellurium, CASRN: 13494-80-9, 0.1 mg/m3) x 3
• TEEL-2 = TEEL-3/6
• TEEL-3 = MW-adjusted IDLH (1990, tellurium, CASRN: 13494-80-9, 50 mg/m3)
This review generated TEEL-3 and TEEL-2 values inconsistent with Rev. 29A. The Rev. 29A and current TEEL-1 source, and values, are consistent. The Rev. 29A TEEL-3 and TEEL-2 were derived from the TEEL-1, while the current basis is the tellurium IDLH, a more preferred source (Table 3.1).