PAC Database - Detailed Chemical Data
Chemical Identity
| Chemical | CAS# | UN# | Health Code Numbers | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chromium(VI) hydroxide | 12626-43-6 |
2.00
4.00
|
||||||||||
| Formula | Synonyms | |||||||||||
| Cr.(O.H)6 | ||||||||||||
Physical Properties
| Mol Wt | State | MP (°C) | BP (°C) | VP (Hg) | VP (°C) | SG | LEL (ppm) |
|---|---|---|---|---|---|---|---|
| 154.0399 | S |
PAC Values
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 0.0015 | 0.30 | 46 |
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 0.00024 | 0.048 | 7.3 |
Technical Basis
A review of available sources identified exposure limits for chromates (Cr(VI) compounds): TWAs (PEL, REL, TLV), TLV-STEL, PEL-C, and an IDLH. The IDLH (1990) was selected as the TEEL-3 basis. The PEL-C was selected as the TEEL-2 basis. The TLV-TWA was selected as the TEEL-1 basis. A compound adjustment factor was applied for all the selected TEEL bases (Section 3.2.2).
• TEEL-1 = MW-adjusted TLV-STEL (Cr(VI) compounds, CASRN: 18540-29-9, 0.0005 mg/m3)
• TEEL-2 = MW-adjusted PEL-C (Cr(VI) compounds, CASRN: 18540-29-9, 0.1 mg/m3)
• TEEL-3 = MW-adjusted IDLH (1990, Chromates [CrO3 basis], CASRN: 1333-82-0, 30 mg/m3)
This review generated a TEEL-3 value consistent with Rev. 29A, and more conservative values for TEEL-2 and TEEL-1. The Rev. 29A TEEL-2 was derived from the TEEL-3, while the current recommendation is for a higher priority TEEL-2 source (Table 3.1). The Rev. 29A TEEL-1 basis was a TLV-TWA, while the current basis, a TLV-STEL, is a higher priority source (Table 3.1).
• TEEL-1 = MW-adjusted TLV-STEL (Cr(VI) compounds, CASRN: 18540-29-9, 0.0005 mg/m3)
• TEEL-2 = MW-adjusted PEL-C (Cr(VI) compounds, CASRN: 18540-29-9, 0.1 mg/m3)
• TEEL-3 = MW-adjusted IDLH (1990, Chromates [CrO3 basis], CASRN: 1333-82-0, 30 mg/m3)
This review generated a TEEL-3 value consistent with Rev. 29A, and more conservative values for TEEL-2 and TEEL-1. The Rev. 29A TEEL-2 was derived from the TEEL-3, while the current recommendation is for a higher priority TEEL-2 source (Table 3.1). The Rev. 29A TEEL-1 basis was a TLV-TWA, while the current basis, a TLV-STEL, is a higher priority source (Table 3.1).
References
Properties of chromium and chromium compounds: https://www.ncbi.nlm.nih.gov/books/NBK158859/
TLV-STEL & PEL-C: https://www.osha.gov/chemicaldata/537
IDLH: https://www.cdc.gov/niosh/idlh/1333820.html