Todd Dunning
Todd DunningMAUnited States
Optical Materials for Laser Systems
Published
Dec 24, 2025

Chromium(VI)

Chemical Properties

Chemical Identity

CAS Number
18540-29-9
Formula
Cr(VI)
Molecular Weight
52 g/mol

Exposure Limits Comparison

Health Effects

Lung Cancer
Yes
Respiratory Irritation
Yes
Skin Ulceration
Yes
Nasal Septum Perforation
Yes

Chromium(VI) safety information

Comprehensive safety and handling requirements

Detection Monitoring
Sensor Types
  • Particulate monitors
  • Personal air sampling pumps
  • Area monitors
  • Colorimetric detection
Detection Range0.0001-100 µg/m³
Alarm Setpoints
Low0.2 µg/m³ (NIOSH REL certain compounds)
High5 µg/m³ (OSHA PEL)
Evacuate15 mg/m³ (15,000 µg/m³) (NIOSH IDLH)
Colorimetric Tubes
  • Dräger Chromium VI 0.1/a
  • Gastec 171
Analytical Methods
MethodTechniqueDetection Limit
NIOSH 7600Visible absorption spectrophotometry0.02 µg/sample
NIOSH 7605Ion chromatography0.05 µg/sample
OSHA ID-215Visible spectrophotometry0.05 µg/sample
Odor ThresholdNot applicable - no warning odor at hazardous levels
Environmental Impact
Aquatic ToxicityVery toxic to aquatic life. LC50 (fish, 96h): 10-100 mg/L depending on species. Cr(VI) more toxic than Cr(III).
BiodegradabilityNot biodegradable. Cr(VI) can be reduced to less toxic Cr(III) by organic matter and reducing conditions.
BioaccumulationLow bioaccumulation potential. Does not concentrate in food chain.
Soil MobilityHigh mobility in soil and groundwater as Cr(VI). Adsorbs less than Cr(III). Contaminates wells.
Atmospheric FateSettles as particulate. Does not react in atmosphere. Washed out by rain.
Ozone Depletionfalse
Reportable Releases
Water5000 lbs to navigable waters
Air5000 lbs/day (CERCLA RQ for soluble Cr(VI))
Ppe Requirements
RespiratoryNIOSH-approved air-purifying respirator with P100 filters for ≤2.5 µg/m³. Powered air-purifying respirator (PAPR) for ≤12.5 µg/m³. SCBA for >12.5 µg/m³ or unknown concentrations.
Eye ProtectionChemical safety goggles, face shield for dusty/spray operations
Skin ProtectionNitrile or neoprene gloves (>4mil thickness). Chemical-resistant clothing. Cr(VI) can cause allergic skin reactions and ulcerations.
Reactivity
StabilityStable under normal conditions. Some compounds decompose when heated.
PolymerizationWill not polymerize
Incompatible Materials
  • Strong reducing agents
  • Combustible materials
  • Organic materials
  • Acids with metals
  • Bases
  • Ammonia
  • Sulfur
  • Phosphorus
Hazardous Decomposition
  • Chromium oxides
  • Toxic fumes
  • Oxygen (chromates)
Conditions To Avoid
  • Heat
  • Incompatible materials
  • Moisture (some compounds)
  • Shock (chromates)
Reactivity HazardSTRONG OXIDIZER. Reacts violently with combustible materials, reducing agents. Chromates may explode when heated. Corrosive to skin and metals.
Regulatory Classification
Un NumberUN3288 (Toxic solid, inorganic, n.o.s.) or UN1755 (Chromic acid solution)
Dot Hazard Class6.1 (Toxic) or 8 (Corrosive)
Dot LabelToxic or Corrosive
Nfpa Codes
Health3
Flammability0
Reactivity1
SpecialOX (Oxidizer)
Epa Hazard Categories
  • Carcinogenicity
  • Acute toxicity
  • Skin corrosion
  • Respiratory sensitization
  • Aquatic toxicity
Sara Title Iiitrue
Cercla Rq5000 pounds (2270 kg) for soluble Cr(VI) compounds
Rcra CodeD007 (chromium)
Storage Requirements
Temperature RangeStore at room temperature, avoid excessive heat
VentilationLocal exhaust ventilation. Store in well-ventilated area away from work areas.
Incompatibilities
  • Combustible materials
  • Organic materials
  • Reducing agents
  • Acids
  • Bases
  • Ammonia
  • Hydrogen sulfide
Container MaterialTightly sealed glass or plastic containers. Polyethylene or glass for chromic acid.
SegregationSeparate from combustibles, organics, and reducing agents by 20 feet or firewall. Designated carcinogen storage.
Quantity LimitsMinimize quantities stored. OSHA requires carcinogen storage protocols.
Special RequirementsPost "CANCER HAZARD" and "STRONG OXIDIZER" signs. Restrict access to authorized personnel. Secondary containment for liquids. Inspect weekly for container integrity. Emergency eyewash/shower within 10 seconds.

Produced From Contaminants

Z-Beam Logo
Z-Beam Logo
Z-Beam Logo
Z-Beam Logo

Produced From Materials

Chromium
Stainless Steel 304
Stainless Steel 316
Stainless Steel

Exposure Limits

Regulatory exposure thresholds and safe concentration levels

Osha Pel Mg M3
0.005
Niosh Rel Mg M3
0.001
Acgih Tlv Mg M3
0.0002
Workplace Exposure
Osha Pel
twa_8hr: 5 µg/m³ (as Cr) - applies to all Cr(VI) compounds
stel_15min: null
ceiling: null
Niosh Rel
twa_8hr: 0.2 µg/m³ (certain Cr(VI) compounds)
stel_15min: null
ceiling: 1 µg/m³ (as Cr)
idlh: 15 mg/m³ (as Cr(VI))
Acgih Tlv
twa_8hr: 0.0002 mg/m³ (0.2 µg/m³) - water-soluble Cr(VI), inhalable
stel_15min: null
ceiling: null
Biological Exposure Indices
0: [object Object]
1: [object Object]

Physical Properties

Physical characteristics and state information

Boiling Point
Varies by compound (chromic acid: decomposes >250°C)
Melting Point
Varies by compound
Vapor Pressure
Negligible at room temperature
Vapor Density
Not applicable (metal/salt)
Specific Gravity
Varies (chromic acid: 1.2)
Flash Point
Not applicable
Autoignition Temp
Not applicable
Explosive Limits
Not applicable
Appearance
Yellow to orange-red crystalline solid (chromates), green solution (chromic acid)
Odor
Odorless or faint acrid odor

Reactivity

Chemical reactivity and compatibility with other substances

Stability
Stable under normal conditions. Some compounds decompose when heated.
Polymerization
Will not polymerize
Incompatible Materials
  • Strong reducing agents
  • Combustible materials
  • Organic materials
  • Acids with metals
  • Bases
  • Ammonia
  • Sulfur
  • Phosphorus
Hazardous Decomposition
  • Chromium oxides
  • Toxic fumes
  • Oxygen (chromates)
Conditions To Avoid
  • Heat
  • Incompatible materials
  • Moisture (some compounds)
  • Shock (chromates)
Reactivity Hazard
STRONG OXIDIZER. Reacts violently with combustible materials, reducing agents. Chromates may explode when heated. Corrosive to skin and metals.

Synonyms & Identifiers

Alternative names and chemical identifiers (CAS numbers)

Synonyms
  • Hexavalent chromium
  • Cr(VI)
  • Chromate
  • Chromic acid
  • Potassium dichromate
  • Sodium chromate
Common Trade Names
  • Chrome plating chemicals
  • Chromate conversion coatings
Other Identifiers
Rtecs Number
GB6200000 (chromic acid)
Ec Number
231-889-5 (chromium trioxide)
Pubchem Cid
24425