Chromium

Agent Name
Chromium
Alternative Name
Chromium and compounds
CAS Number
7440-47-3; varies
Formula
Cr, varies
Major Category
Metals
Synonyms
Chrome; Chromium compounds; [NIOSH]
Category
Chromium Compounds, Inorganic
Description
Blue-white to steel-gray, lustrous, brittle, hard, odorless solid; [NIOSH]
Sources/Uses
MINING, SMELTING, OR METALLURGY: Ore mining and crushing operations; Alloy production; Produce chromates from chromite; MANUFACTURING: Textile dyes; Paint pigments; Chrome plating; Leather tanning; Printing inks and toners; Photoengraving; Automotive & aircraft parts; Joint prostheses; Refractory bricks & kilns; USING: Heat or machine chromium alloys; Arc weld stainless steel; Spray paint Cr pigments; Mix and lay cement or concrete; Use water system corrosion inhibitors, wood preservatives, or glassware-cleansing solutions; Use hexavalent chromates in hardeners for epoxy resin sealants; "Chromium(VI) is present also as an impurity in Portland cement, and can be generated and given off during casting, welding, and cutting operations involving stainless steel, even if chromium was not originally present in its hexavalent state." [ACGIH] "Stainless steels are a group of iron-based alloys containing at least 10.5% chromium. Chromium is used to make stainless steel corrosion resistant. . . . In ferrochromium operations, trivalent (insoluble) chromium (Cr3+) predominates, but hexavalent (soluble) chromium (Cr6+) also occurs at low levels, usually at below 1 ug m-3." [PMID 26950803]
Comments
Chromium metal and Cr(III) compounds are IARC 3 (not classifiable), while the hexavalent chromium Cr(VI) compounds are IARC 1 (human carcinogens); Water-soluble, Cr(VI) compounds have the “skin” designation. All Cr(VI) compounds are designated as RSEN and DSEN, meaning that they may cause asthma and allergic contact dermatitis. Kidney injury has been reported in workers exposed to hexavalent chromium compounds, but no quantitative exposure information is available. Reproductive studies of workers handling Cr(VI) compounds are inconclusive. “The severe corrosive effects of Cr(VI) compounds can lead to ulceration of the skin ("chrome holes") and mouth, rhinitis, and perforation of the nasal septum." [ACGIH] "Among chromate production workers, virtually all studies showed excess risks of lung cancer, except for a few estimates of risks for US workers hired since exposures were lowered . . . " [IARC Monograph 100C, p. 154] "Compounds of Cr III do not cause chrome ulcerations and do not generally initiate allergic dermatitis without prior sensitization by Cr(VI) compounds." [ILO Encyclo: Chromium] “ . . .induction of sensitization by water-soluble Cr(III) compounds independently of Cr(VI) exposures cannot be ruled out.” [ACGIH] Chromates, the most common cause of allergic contact dermatitis, are released as hexavalent chromium from chrome-plated metal tools and machine parts. [Marks, p. 117-9] Chromium is genotoxic, and animal experiments show effects on sperm motility. No available evidence of birth defects in humans. [Frazier] Chronic exposure to hexavalent chromium may cause mild to moderate liver injury. [ATSDR Case Studies # 4] Asthma reported in printer, plater, welder, and tanner (chromium and nickel); [Malo] Allergic contact dermatitis in agricultural workers, construction workers, mechanics, and printers; [Marks] Can cause immunologic, occupational contact urticaria; [Kanerva, p. 219] Humans are exposed to Cr III compounds in food with no known adverse effects. Cr III compounds are at least 500 times less toxic than Cr VI compounds. "Organic Cr-containing complexes of toxicological importance have not been reported." [Nordberg, p. 717-8]
Biomedical References

Exposure Assessment

BEI
Chromium(VI), water-soluble fume (applicable for manual metal arc stainless steel welding only): Total Cr in urine = 10 ug/L (increase during shift) or 25 ug/L (end of shift at end of workweek)
Bioaccumulates
Yes
TLV (ACGIH)
0.5 mg/m3, as Cr(0), inhalable particulate matter, 0.003 mg/m3, (Cr(III), inhalable particulate matter), 0.0002 mg/m3, as Cr(VI), inhalable particulate matter
STEL (ACGIH)
0.0005 mg/m3, as Cr(0), inhalable particulate matter, 0.003 mg/m3, (Cr(III), inhalable particulate matter), 0.0002 mg/m3, as Cr(VI), inhalable particulate matter
PEL (OSHA)
1 mg/m3(metal), 0.5 mg/m3, as Cr(Cr(II) and Cr(III) inorganic compds), 0.005 mg/m3, as Cr(VI)(water sol. And insol. Inorganic compds)
IDLH (NIOSH)
250 mg/m3,as Cr(metal and Cr(II)compds), 25 mg/m3, as Cr(Cr(III)compds)
Excerpts from Documentation for IDLHs
The available toxicological data show no evidence that an acute exposure to a high concentration of chromium metal would impede escape or cause any irreversible health effects within 30 minutes.
Explanatory Notes
Melting Point = 3452 degrees F; Boiling Point = 4788 degrees F;
Half Life
Blood: 24 days; body: initial elimination 1/2 life = 2-3 days; extended 1/2 life = 1 month; [TDR, p. 368] After chronic exposure, workers can have high levels of chromium in the urine for years. [ACGIH]
Reference Link #2

Adverse Effects

Skin Sensitizer
Yes
Asthma
Yes
Hepatotoxin
Hepatoxic (a) from occupational exposure (secondary effect) or (b) in animal studies or in humans after ingestion
Nephrotoxin
Yes
Dermatotoxin
Skin burns
IARC Carcinogen
Established
NTP Carcinogen
Human carcinogen
ACGIH Carcinogen
Confirmed Human

Diseases, Processes, and Activities Linked to This Agent