A review of available sources identified an exposure limit (OEL-TWA) and acute toxicity data (LD50) for several species and 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 species and route toxicity data, a rat oral LD50, was selected as the TEEL-3 basis. TEEL-2 was derived according to Table 3.5. The OEL-TWA was selected as the TEEL-1; this exposure limit was reported “as Cu”, therefore, a compound adjustment factor was applied (Section 3.2.2).
• PAC-1 = TEEL-1 = MW-adjusted OEL-TWA (Finland, as copper, 0.02 mg/m3) x 3
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat oral LD50 (1350 mg/kg)
This review generated PAC-3 and PAC-2 values consistent with Rev. 29A, and an inconsistent PAC-1 value. Rev. 29A and current TEEL-3 and TEEL-2 source, and methodologies are consistent. The Rev. 29A TEEL-1 basis was a copper TLV-TWA, while the current TEEL-1 basis is a chemical specific OEL-TWA.