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Chromic acid and chromates

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Synonyms & Trade Names
Chromic acid (CrO3), Chromic anhydride, Chromic oxide, Chromium(VI) oxide (1:3), Chromium trioxide, Zinc chromate
CAS No.
1333-82-0 (CrO3)
RTECS No.
GB6650000 (CrO3)
DOT ID & Guide
1755 154(acid solution)
1463 141(acid, solid)
Formula
CrO₃ (acid)
Conversion
IDLH
Ca [15 mg/m3 {as Cr(VI)}]
See: 1333820
Exposure Limits
NIOSH REL
(as Cr): Ca TWA 0.0002 mg/m3 (8-hours) See Appendix A See Appendix C
OSHA PEL
(as CrO3): TWA 0.005 mg/m3 See Appendix C
Measurement Methods
NIOSH 7600 , 7604 , 7605 , 7703 , 9101;
OSHA ID103 , ID215 , W4001
See: NMAM or OSHA Methods
Physical Description
CrO3: Dark-red, odorless flakes or powder. [Note: Often used in an aqueous solution (H2CrO4).]
Molecular Weight
100.0
Boiling Point
482°F (Decomposes)
Melting Point
387°F (Decomposes)
Solubility
63%
Vapor Pressure
Very low
Ionization Potential
NA
Specific Gravity
2.70 (CrO3)
Flash Point
NA
Upper Explosive Limit
NA
Lower Explosive Limit
NA
CrO3: Noncombustible Solid, but will accelerate the burning of combustible materials.
Incompatibilities & Reactivities
Combustible, organic, or other readily oxidizable materials (paper, wood, sulfur, aluminum, plastics, etc.); corrosive to metals
Exposure Routes
inhalation, ingestion, skin and/or eye contact
Symptoms
irritation respiratory system; nasal septum perforation; liver, kidney damage; leukocytosis (increased blood leukocytes), leukopenia (reduced blood leukocytes), eosinophilia; eye injury, conjunctivitis; skin ulcer, sensitization dermatitis; [potential occupational carcinogen]
Target Organs
Blood, respiratory system, liver, kidneys, eyes, skin
Cancer Site
[lung cancer]
Personal Protection/Sanitation
(See protection codes)
Skin:Prevent skin contact
Eyes:Prevent eye contact
Wash skin:When contaminated
Remove:When wet or contaminated
Change:Daily
Provide:Eyewash, Quick drench
First Aid
(See procedures)
Eye:Irrigate immediately
Skin:Soap flush immediately
Breathing:Respiratory support
Swallow:Medical attention immediately
Respirator Recommendations

NIOSH

At concentrations above the NIOSH REL, or where there is no REL, at any detectable concentration:
(APF = 10,000) Any self-contained breathing apparatus that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode
(APF = 10,000) Any supplied-air respirator that has a full facepiece and is operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained positive-pressure breathing apparatus

Escape:


(APF = 50) Any air-purifying, full-facepiece respirator with an N100, R100, or P100 filter.
Click here for information on selection of N, R, or P filters. 


Any appropriate escape-type, self-contained breathing apparatus

Important additional information about respirator selection

See also
INTRODUCTION   ICSC CARD: 1194   MEDICAL TESTS: 0051
Page last reviewed: October 30, 2019
Content source: National Institute for Occupational Safety and Health