SILICA, CRYSTALLINE, MIXED RESPIRABLE (QUARTZ, CRISTOBALITE, TRIDYMITE)‡

Chemical Identification
Chemical Identification
CAS # 14808-60-7 (quartz), 14464-46-1 (cristobalite), 15468-32-3 (tridymite)
Formula

Mixed

Synonyms

silica; crystalline silica; quartz; quartz dust; critobalite; cristobalite dust; tripoli

Physical Properties
Physical Properties
Physical description Colorless, odorless solid.
Boiling point 4046°F Molecular weight 60.1
Freezing point/melting point 3110°F Vapor pressure 0 mmHg (approx)
Flash point Vapor density
Specific gravity 2.66 Ionization potential
Lower explosive limit (LEL) Upper explosive limit (UEL)
NFPA health rating NFPA fire rating
NFPA reactivity rating NFPA special instruction
Vapor hazard ratio (VHR)
Historical exceedance percentage
Target organs
Monitoring Methods Used by OSHA
Monitoring Methods Used by OSHA
Analyte code (IMIS no.) 9000
Sampling group
Sampler/Sampling media Tared low-ash 37 mm PVC filter, 5 microns, preceded by 10 mm nylon Dorr-Oliver cyclone for respirable samples. [SLTC108]
Sampling time*

240-480 min

Sampling volume (TWA)*

816 L

Sampling flow rate (TWA)*

1.7 L/min ±0.2 L/min

Sampling volume (STEL/Peak/C)*

408-816 L

Sampling flow rate (STEL/Peak/C)*

1.7 L/min ±0.2 L/min

 

Analytical method instruments XRD
Method reference OSHA ID-142 (fully validated)
Notes

OSHA personnel must obtain pre-weighted filters from SLTC. Quartz and cristobalite analysis may be submitted on the same filter. If a bulk sample is taken, send it to the lab in a separate mailing container from associated air samples. Bulk sampling is optional. In cases where bulk samples are submitted high-volume filter samples (without cyclones, preferably >1 g), and representative settled dust are preferred. Request analysis for Silica, Crystalline, Mixed Respirable (Quartz, Cristobalite, Tridymite), IMIS Code 9000.  

Cristobalite is a polymorph of respirable crystalline silica that occurs in workplaces where silica is heated to extremely hot temperatures (>1460 °C).  If it is suspected that cristobalite may be present, note this on the Form OSHA-91A. Cristobalite is rare and will usually only be analyzed if the reason to suspect its presence is noted on the Form 91A. Tridymite, which is even rarer, will not be analyzed by SLTC because a standard reference material is not readily available.

Special requirements

The 10-mm nylon Dorr-Oliver operated at an optimized flow rate of 1.7 L/min is capable of collecting a sufficient quantity of quartz to exceed the limit of quantification when airborne concentrations are at or above the action level, provided that at least 4-hour air samples are taken.

* All sampling instructions above are recommended guidelines for OSHA Compliance Safety and Health Officers (CSHOs), please see the corresponding OSHA method reference for complete details.

Wipe Method
Wipe Method
Sampler/Sampling media
Bulk Method
Bulk Method
On-Site Screening Techniques
On-Site Screening Techniques
Device
Model/Type
Sampling information
(see manufacturer instructions)
Exposure Limits
Exposure Limits
OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
NIOSH REL
Up to 10-hour TWA
(ST) STEL
(C) Ceiling
ACGIH TLV©
8-hour TWA
(ST) STEL
(C) Ceiling
CAL/OSHA PEL
8-hour TWA
(ST) STEL
(C) Ceiling
Peak
PEL-TWA

50 µg/m³ [25 µg/m³ Action Level]

REL-TWA

0.05 mg/m³

TLV-TWA

0.025 mg/m³ (respirable particulate matter), [2009]

PEL-TWA

0.05 mg/m³

PEL-STEL REL-STEL TLV-STEL PEL-STEL
PEL-C REL-C TLV-C PEL-C
Skin notation

N

Skin notation

N

Skin notation

N

Skin notation

N

Notes:

See 29 CFR 1910.1053, Respirable crystalline silica. See 29 CFR 1910.1000 Table Z-3, Mineral Dusts for any operations or sectors where the exposure limits in 1910.1053 are stayed or otherwise not in effect.

Notes:

CARCINOGEN (Ca): RESPIRABLE FRACTION, REDUCE EXPOSURE TO LOWEST FEASIBLE CONCENTRATION. See Appendix A, NIOSH Potential Occupational Carcinogens.

Notes:

See Appendix C: Particle Size-Selective Sampling Criteria for Airbone Particulate Matter

Notes:

See footnote (n). See also California Code of Regulations, Title 8 §5204. Occupational Exposures to Respirable Crystalline Silica, and §2532.3. Occupational Exposures to Crystalline Silica.

Health factors:  See NIH-NLM PubChem. IDLH

50 mg/m³

Carcinogenic classifications: IARC-1, NIOSH-Ca, NTP-K, TLV-A2, MAK-1 Notes:

Ca

AIHA emergency response planning guidelines - ERPG-1/ERPG-2/ERPG-3:
Additional Resources and Literature References
Additional Resources and Literature References

NOAA: CAMEO Chemicals -

NIOSH: Pocket Guide to Chemical Hazards - Silica, crystalline (as respirable dust)

Literature References

  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Silica, Crystalline - Alpha quartz [1317-95-9; 14808-60-7] and cristobalite [14464-46-1]. See annual publication for most recent information.
  • American Thoracic Society: Adverse effects of crystalline silica exposure. Am J Respir Crit Care Med. 155:761-768, 1997.
  • IARC: IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 68, Silica. 1997.
  • IARC: IARC Monographs: Arsenic, Metals, Fibres, and Dusts, A Review of Human Carcinogens, Volume 100 C. 2012.
  • IARC: Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man. Geneva: World Health Organization, International Agency for Research on Cancer, 1972-PRESENT. (Multivolume work). Available at: http://monographs.iarc.fr/index.php p. V68, 183, 1997.
  • NIOSH: Criteria for a Recommended Standard - Occupational Exposure to Crystalline Silica. 1974.
  • NIOSH: Occupational Health Guideline for Crystalline Silica. 1978.
  • Parks, C.G., Conrad, K., Cooper, G.S.: Occupational exposure to crystalline silica and autoimmune disease. Environ Health Perspect. 107 Suppl 5:793-802, Oct 1999.
  • Steenland, K.; Attfield, M.; Mannejte, A. Pooled Analyses of Renal Disease Mortality and Crystalline Silica Exposure in Three Cohorts. Ann. Occup. Hyg. 2002, 46, 4-9.

Last Updated Date : 01/11/2021