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This document may not reflect OSHA's respirable silica rule published on March 25, 2016.
For more information on the new rule, see OSHA's Respirable Crystalline Silica Safety and Health Topics Page.

Silica, Crystalline Cristobalite, Respirable Dust

General Description

Synonyms:  Cristobalite; Cristobalite dust

OSHA IMIS code: 9000 (reported as an individual polymorph prior to 2016 - cristobalite 9015)

CAS number(s): 14464-46-1

Exposure Limits and Health Effects (Updated September 6, 2012)

Standard Set By Exposure Limit Health Effect Codes -- Health Effects and Target Organs
OSHA PEL - General Industry
See 29 CFR 1910.1000 Table Z-3
Use ½ the value calculated from the count or mass formulae for quartz HE10 -- silicosis
OSHA PEL - Construction Industry
See 29 CFR 1926.1153
50 μg/m3 TWA
25 μg/m3 TWA Action Level
HE1 -- cancer (lung)
HE3 -- kidney damage
HE10 -- silicosis
OSHA PEL - Shipyard Employment
See 29 CFR 1915.1000 Table Z - Shipyards
20 mppcf HE10 -- silicosis
NIOSH REL

Silica, crystalline (as respirable dust) [14808-60-7]: 0.05 mg/m3 TWA
Ca
See Appendix A

HE10 -- silicosis
ACGIH TLV® (2009) Silica, crystalline - α-quartz [1317-95-9; 14808-60-7] and cristobalite [14464-46-1]: 0.025 mg/m3 (25 μg/m3) (respirable particulate matter) TWA
A2
HE2 -- lung cancer
HE10 -- silicosis
CAL/OSHA PELs Cristobalite, respirable dust [14464-46-1]: 0.05 mg/m3 (50 μg/m3) TWA  

mppcf = Millions of particles per cubic foot of air

Carcinogenic classification:

EPA Inhalation Reference Concentration (RfC): Not established

ATSDR Inhalation Minimal Risk Levels (MRLs): Not established

NIOSH 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).

Partial reference list:

  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Silica, Crystalline - Alpha Quartz and Cristobolite. 2016.
  • 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.
  • NIOSH: Criteria for a Recommended StandardOccupational Exposure to Crystalline Silica. 1974.
  • NIOSH: Occupational Health Guideline for Crystalline Silica. 1978.
  • NIOSH/CEC/ICPS: International Chemical Safety CardsCristobalite. 1997.

Chemical Sampling Information

By Name

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

By CAS Number

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