A review of available sources identified the following: a TLV-TWA for nickel (CASRN: 7440-33-7) and LD50, (dog, rat) 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. The most preferred route, a rat oral LD50, was selected as the TEEL-3 basis. The TEEL-2 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 adjusted TLV-TWA (nickel CASRN: 7440-33-7, 0.1 mg/m3) x 3
• TEEL-2 = TEEL-3/6
• TEEL-3 = Rat oral LD50 (105 mg/kg)
This review generated TEEL-3 and TEEL-2 values inconsistent with Rev. 29A. The Rev. 29A and current TEEL-3 basis are both rat oral LD50 acute toxicity data, however the previous basis was not found during review, so the lower, available source was used instead. TEEL-2 values differ due to the change in TEEL-3 basis. The Rev. 29A and current TEEL-1 values and methodology are consistent.