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Silica, Crystalline Cristobalite, Respirable Dust

General Description

  • Synonyms: Cristobalite; Cristobalite dust
  • OSHA IMIS Code Number: 9015
  • Chemical Abstracts Service (CAS) Registry Number: 14464-46-1
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: VV7330000
  • NIOSH Pocket Guide to Chemical Hazards - Silica, Crystalline, Respirable Dust: Chemical description, physical properties, potentially hazardous incompatibilities, and more

Exposure Limits and Health Effects

Exposure Limit Limit Values HE Codes Health Factors and Target Organs

Use ½ the value calculated from the count or mass formulae for quartz

HE10

Silicosis

20 mppcf*

HE10

Silicosis

20 mppcf*

HE10

Silicosis

  • National Institute for Occupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)
  • (Listed under Crystalline Silica)
  • See Appendix A
  • 0.05 mg/m3 TWA
  • Ca

HE10

Silicosis

American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) (2010)

  • 0.025 mg/m3
  • A2

HE2

Lung cancer

HE10

Silicosis

CAL/OSHA PEL

0.05 mg/m3 TWA

 

 

*mppcf = Millions of particles per cubic foot of air

  • National Toxicology Program (NTP) carcinogenic classification: Known to be a human carcinogen (PDF)
  • International Agency for Research on Cancer (IARC) carcinogenic classification: Group 1 (carcinogenic to humans); see also IARC Monograph 100C (PDF)
  • U.S. Environmental Protection Agency (EPA) carcinogenic classification: Not listed
  • EPA Inhalation Reference Concentration (RfC): Not established
  • Agency for Toxic Substances and Disease Registry (ATSDR) Inhalation Minimal Risk Level (MRL): Not established
  • NIOSH Immediately Dangerous to Life or Health (IDLH) concentration: 25 mg/m3
  • Notes on Other Potential Health Effects and Hazards
    1. Silicosis increases risk of tuberculosis and other respiratory diseases (American Thoracic Society 1997).
    2. Extrapulmonary silicosis has also been found, where lesions spread to the liver, spleen, kidneys, bone marrow, and extrathoracic lymph nodes (IARC 1997).
  • Date Last Revised: 9/6/2012
  • Literature Basis

Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method:
  • Preweighed Tared Low Ash Polyvinyl Chloride (LAPVC) filter 5 microns preceded by 10 mm Nylon Dorr-Oliver Cyclone
  • maximum volume: 816 Liters
  • maximum flow rate: 1.7 L/min
  • current analytical method: X-ray Diffraction; XRD
  • method reference: OSHA Analytical Method (OSHA ID-142)
  • method classification: Fully Validated
  • note: OSHA personnel must obtain filter from SLTC. Collect a sample of the bulk substance and send to the lab in a separate mailing container at the time the air samples are submitted. Indicate on the sample sheet that a bulk sample has been submitted. For SiO2, a high volume area or settled dust sample is preferred. If submitting high volume sample collect at least 5 grams of dust, clearly mark samples to be used for reference as a bulk. Any sample weight between 0.10 mg and 5.0 mg is acceptable (0.5 to 3.0 mg is preferred). If they are present in the work environment, the following major interferences should be noted: aluminum phosphate, feldspars (microcline orthoclase, plagioclase), graphite, iron carbide, lead sulphate, micas (biotite, muscovite), montomorillonite, potash, sillimanite, silver chloride, talc and zircon (zirconium silicate). Quartz and cristobalite may be submitted on the same filter, otherwise, submit as separate filter.

** All Trademarks are the property of their respective owners.

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