PAC Database - Detailed Chemical Data
Chemical Identity
| Chemical | CAS# | UN# | Health Code Numbers | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hafnium | 7440-58-6 | 2545 |
18.00
15.01
15.02
11.01
11.00
10.00
3.10
4.10
|
|||||||||
| Formula | Synonyms | |||||||||||
| Hf | HAFNIUM POWDER, DRY, HAFNIUM POWDER, WETTED WITH NOT LESS THAN 25% WATER, CELTIUM, ELEMENTAL HAFNIUM, HAFNIO, EN POLVO, HUMEDECIDO CON NO MENOS DEL 25% DE AGUA (D, HAFNIUM ELEMENT, HAFNIUM EN POUDRE, HUMIDIFIÉ AVEC AU MOINS 25% D^EAU (DOT FR, HAFNIUM METAL | |||||||||||
Physical Properties
| Mol Wt | State | MP (°C) | BP (°C) | VP (Hg) | VP (°C) | SG | LEL (ppm) |
|---|---|---|---|---|---|---|---|
| 178.49 | S | 2233 | 4603 | 2416 | 13.3 |
PAC Values
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 0.50 | 5.5 | 33 |
| PAC-1 | PAC-2 | PAC-3 |
|---|---|---|
| 0.068 | 0.75 | 4.5 |
Technical Basis
A review of available sources identified exposure limits (IDLH, OELs) for hafnium. Data sources were selected according to the hierarchy listed in Table 3.1. Analysts selected lowest reported OEL-STEL (Romania, 15-minutes) as the TEEL-1. The TEEL-2 was derived according to Table 3.5. The 1990 and 1994 IDLH were evaluated for the TEEL-3; the 1990 IDLH was an “effective” limit, while the 1994 IDLH was developed a limited data set (2 studies) of dissimilar chemicals. Considering this, analysts did not select the IDLH as a TEEL-3. Instead, the TEEL-3 was derived according to Table 3.5.
• PAC-1 = TEEL-1 = OEL-STEL (Romania, 0.5 mg/m3)
• PAC-2 = TEEL-2 = TEEL-1 x 11
• PAC-3 = TEEL-3 = TEEL-2 x 6
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A TEEL-1 basis was a TLV-TWA, while the current TEEL-1 basis is an OEL-STEL (Table 3.5, see note). The Rev. 29A and current TEEL-2 and TEEL-3 use the same methodology, with differences due to the change in TEEL-1.
• PAC-1 = TEEL-1 = OEL-STEL (Romania, 0.5 mg/m3)
• PAC-2 = TEEL-2 = TEEL-1 x 11
• PAC-3 = TEEL-3 = TEEL-2 x 6
This review generated PAC values inconsistent with Rev. 29A. The Rev. 29A TEEL-1 basis was a TLV-TWA, while the current TEEL-1 basis is an OEL-STEL (Table 3.5, see note). The Rev. 29A and current TEEL-2 and TEEL-3 use the same methodology, with differences due to the change in TEEL-1.
References
Chemical information: https://pubchem.ncbi.nlm.nih.gov/compound/Hafnium.
IDLH: https://www.cdc.gov/niosh/idlh/7440586.html
Exposure limits: https://www.osha.gov/chemicaldata/542
OELs (TWAs, STEL): https://ilv.ifa.dguv.de/limitvalues/30587