A review of available sources identified exposure limits (OEL-TWAs) and acute toxicity data (LD50) for cupric oxide. 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 a route, a rat oral LD50, was selected as the TEEL-3 basis. The TEEL-2 was derived according to Table 3.5. The lowest reported OEL-TWA was selected as the TEEL-1 basis and a compound adjustment factor was applied (Section 3.2.2) because the reported basis for this TWA is copper.
• PAC-1 = TEEL-1 = MW-adjusted OEL-TWA (as Cu, 0.02 mg/m3) x 3
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = Rat oral LD50 (470 mg/kg)
This review generated PAC-3 value consistent with Rev. 29A and inconsistent PAC-2 and PAC-1 values. The Rev. 29A and current TEEL-3 basis and methodology are consistent. The Rev. 29A TEEL-2 basis was a mouse intraperitoneal not found during this review; instead, the TEEL-2 was derived from the TEEL-3. The Rev. 29A TEEL-1 was a weight adjusted TLV-TWA for copper, while the current TEEL-1 basis is a weight adjusted OEL-TWA for cupric oxide.