A review of available sources identified exposure limits (OEL-TWAs) and acute toxicity data (LD50, LDLo, TDLo) 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. Several rat oral LD50 were evaluated; of these, the lowest (300 mg/kg) was not selected because it was also reported under the toxicity for cupric sulfate (CASRN: 7758-98-7). Considering this, the next lowest value rat oral LD50 (438 mg/kg) was selected as the TEEL-3 basis. Human TDLo data did not report appropriate toxicity endpoints and was therefore not selected for TEEL development (Section 3.3.2). 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 (481 mg/kg)
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A TEEL-3 basis was a less conservative rat oral LD50 not found during the current review; instead, the current TEEL-3 basis is a lower dose rat oral LD50. The Rev. 29A and current TEEL-2 use the same methodology, with differences due to the change in 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 copper(II) sulfate pentahydrate.