A review of available sources identified exposure limits (OEL-TWAs) 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. The TEEL-2 value was derived according to Table 3.5. The lowest reported OEL-TWA (Finland) 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 (584 mg/kg)
This review generated PAC values inconsistent with Rev. 29A. Rev. 29A TEEL-1 basis was a weight adjusted copper TLV-TWA, from which TEEL-2 and TEEL-3 values were derived; The current TEEL-1 basis is a chemical specific OEL-TWA. The current TEEL-3 basis is a rat oral LD50, from which the TEEL-2 was derived (Table 3.5).