PAC Database - Detailed Chemical Data
Chemical Identity
| Chemical | CAS# | UN# | Health Code Numbers | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chromic oxide; (Chromium(III) oxide; Chromium sesquioxide) | 1308-38-9 |
10.00
11.01
3.10
16.01
3.09
|
||||||||||
| Formula | Synonyms | |||||||||||
| Cr2O3 | ||||||||||||
Physical Properties
| Mol Wt | State | MP (°C) | BP (°C) | VP (Hg) | VP (°C) | SG | LEL (ppm) |
|---|---|---|---|---|---|---|---|
| 151.99 | S crystals | 2320 | 5.22 |
PAC Values
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 2.2 | 61 | 370 |
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 0.35 | 9.8 | 60 |
Technical Basis
A review of available sources identified a TLV-TWA and IDLH for chromium (CASRN: 7440-47-3). Data sources were selected according to the hierarchy listed in Table 3.1. There is no reported 1990 IDLH; instead, an effective value based on 500 x OSHA PEL (0.5 mg/m3) was reported. This limit was adjusted with a compound adjustment factor (Section 3.2.2). A TEEL-2 value was calculated according to Table 3.5. The TLV-TWA was selected, adjusted with a compound adjustment factor (Section 3.2.2), and calculated according to Table 3.5.
• TEEL-1 = MW-adjusted TLV-TWA x 3 (0.5 mg/m3, Chromium CASRN: 7440-47-3)
• TEEL-2 = TEEL-3/6
• TEEL-3 = MW-adjusted IDLH (250 mg/m3, Chromium CASRN: 7440-47-3)
This review generated TEEL-1 values consistent with Rev. 29A. TEEL-2 and TEEL-3 are less conservative, as they were previously derived from TEEL-1 using the fill gap adjustment factors (Table 3.5). This conservatism was investigated; NIOSH reports that trivalent chromium compounds have a low order of toxicity and provide little industrial hazard (ACGIH 1971; Akatsuka and Fairhall 1934; Clayton and Clayton 1981). ThermoFisher Scientific reported a Health Hazard Rating (HHR) of 1 (correlated to TEEL-3 = 7900 mg/m3) associated with chromic oxide. With this, the less conservative values reported in the recommendation appear appropriate.
• TEEL-1 = MW-adjusted TLV-TWA x 3 (0.5 mg/m3, Chromium CASRN: 7440-47-3)
• TEEL-2 = TEEL-3/6
• TEEL-3 = MW-adjusted IDLH (250 mg/m3, Chromium CASRN: 7440-47-3)
This review generated TEEL-1 values consistent with Rev. 29A. TEEL-2 and TEEL-3 are less conservative, as they were previously derived from TEEL-1 using the fill gap adjustment factors (Table 3.5). This conservatism was investigated; NIOSH reports that trivalent chromium compounds have a low order of toxicity and provide little industrial hazard (ACGIH 1971; Akatsuka and Fairhall 1934; Clayton and Clayton 1981). ThermoFisher Scientific reported a Health Hazard Rating (HHR) of 1 (correlated to TEEL-3 = 7900 mg/m3) associated with chromic oxide. With this, the less conservative values reported in the recommendation appear appropriate.
References
American Conference of Governmental Industrial Hygienists TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices. Cincinnati, OH 2015, p. 21. Retrieved from: https://pubchem.ncbi.nlm.nih.gov/source/hsdb/1619
Table of IDLH values; via NIOSH: https://www.cdc.gov/niosh/idlh/cr3m3.html
ThermoFisher Scientific, chromic oxide SDS (2010): https://www.fishersci.com/store/msds?partNumber=C3333&productDescription=CHROMIC+OXIDE+SESQUI+TECH+3KG&vendorId=VN00033897&countryCode=US&language=en