# NIOSH Pocket Guide to Chemical Hazards
Chromic acid and chromates | CAS 1333-82-0 (CrO3)
CrO3 (acid) | RTECS GB6650000 (CrO3)
Synonyms & Trade Names Chromic acid (CrO3): Chromic anhydride, Chromic oxide, Chromium(VI) oxide (1:3), Chromium trioxide Synonyms of chromates (i.e., chromium(VI) compounds) such as zinc chromate vary depending upon the specific compound. | DOT ID & Guide 1755 154 (acid solution) 1463 141 (acid, solid)
Exposure Limits | NIOSH REL (as Cr): Ca TWA 0.001 mg/m3 See Appendix A See Appendix C
OSHA PEL (as CrO3): C 0.1 mg/m3 See Appendix C
IDLH Ca [15 mg/m3 {as Cr(VI)}] | Conversion
Physical Description CrO3: Dark-red, odorless flakes or powder. [Note: Often used in an aqueous solution (H2CrO4).]
MW: 100.0 | BP: 482°F (Decomposes) | MLT: 387°F (Decomposes) | Sol: 63%
VP: Very low | IP: NA |  | Sp.Gr: 2.70 (CrO3)
Fl.P: NA | UEL: NA | LEL: 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
Measurement Methods NIOSH 7600, 7604; OSHA ID103, ID215
Personal Protection & Sanitation 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 a high-efficiency particulate filter/Any appropriate escape-type, self-contained breathing apparatus
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]
See also: INTRODUCTION