A review of available sources identified the acute toxicity data (LD50, LD75) for limited species and routes. In addition, analysts evaluated exposure limits for chromium compounds (Cr(VI), hexavalent chromium) for TEEL development, as this is the more toxic component of this compound. 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 1990 IDLH for chromates was selected as the TEEL-3 basis and a compound adjustment factor was applied (Section 3.2.2). The TEEL-2 was derived according to Table 3.5. The TLV-STEL for chromium VI compounds was selected as the TEEL-1 and a compound adjustment factor was applied (Section 3.2.2).
• PAC-1 = TEEL-1 = MW-adjusted TLV-STEL (chromium VI compounds, 0.0005 mg/m3)
• PAC-2 = TEEL-2 = TEEL-3/6
• PAC-3 = TEEL-3 = IDLH (1990, chromates (as CrO3, CASRN: 1333-82-0), 30 mg/m3)
This review generated PAC-3 and PAC-2 values consistent with Rev. 29A and a PAC-1 inconsistent. The Rev. 29A and current TEEL-3 and TEEL-2 source, and methodology are consistent. The Rev. 29A TEEL-1 basis was a TLV-TWA, while the current TEEL-1 is a weight adjusted chromium VI compound TLV-STEL.