Chromium
Physico-chemical properties
DACTARI
Element
Symbol
Atomic number
Atomic weight
Chemical series
Discovered
Origin of the name
Electron configuration
Density
Melting point
Boiling point
Pearson classification (acid and base)
Electronegativity (Pauling scale)
Ionic Radius (Marcus)
Coordination number
Oxidation states (main in bold)
Redox potential
Main mineral compounds (solids)
Main Industrial compounds (solids)
Main industrial compounds (solution)
Biological role
Main isotopes
Chromium
Cr
24
52.0
Transition metal
Isolated by L.N.Vauquelin in 1798
From greek word “chroma” which means color
[Ar] 3d5 4s1
7.20 g/cm3
1907°C
2671°C
Hard
1.66
0.62 Å (Cr3+) ; 2.40 Å (CrO4=)
6
II, III (Cr3+), IV, VI (CrO42-)
-0.74 (Cr3+/Cr), 1.33 (Cr6+/Cr3+)
Chromite (FeCr2O4), bellite (PbCrO4,As4,SiO2)),
crocoite (PbCrO4), bentonite, mariposite…
CrO2, Cr2O3, Cr2S3, (NH4)2Cr2O7, Na2Cr2O7,
K2CrO4,PbCrO4…
Organics: Chromium hexacarbonyl Cr(CO)6…
Chromate (CrO4=), dichromate (Cr2O7=)
Not present. Influence sugar and lipid metabolism
51Cr (T1/2 = 27.7 d, β,) (1g = 3.42 1015 Bq)
Chromium
Acute toxicity
DACTARI
Element
Symbol
Chromium (VI) (all soluble compounds)
Chromium (VI) trioxide : CrO3
Dichromate (VI) (K, Na, NH4)
Sodium chromate
Strontium chromate
Chromium (III) (all soluble compounds)
Chromium acetate
Chromium nitrate
References
Fractional absorption : fA (ICRP 100)
Materno-fœtal transfer (ICRP 88)
Chromium
Cr
LD 50 (mg/kg) (rat/oral)
Classification LD50*
13 – 811
2-4
25 – 29 (ATSDR)
2
27 – 59 (Ineris)
2
16 – 26 (Ineris)
2
50 – 160 (INRS)
2-3
13-28
2
811
4
183 - 2365
3 - NC
2365
NC
183 - 200
3
ATSDR, Ineris, EPA, INRS (FT180), HSDB
Cr(VI) : 0.1 (ICRP 72)
/
*Classification of Acute Toxicity on the Basis of the LD 50.
Exposure Route
Oral (mg/kg
bodyweight)
Dermal (mg/kg
bodyweight)
Gases (ppmV)
Vapours (mg/l)
Category 1
Category 2
Category 3
Category 4
ATE < 5
5 < ATE < 50
50 < ATE < 300
300 < ATE < 2000
ATE ≤ 50
50 < ATE < 200
200 < ATE < 1000
1000 < ATE < 2000
ATE < 100
100 < ATE < 500
500 < ATE < 2500
2500 < ATE < 20000
ATE < 0.5
0.5 < ATE < 2.0
2.0 < ATE < 10.0
10.0 < ATE < 20.0
*Acute toxicity hazard categories and acute toxicity estimates (ATE)
* Classification du GHS (United Nations Globally Harmonised System of Classification and Labelling of
Chemicals) des DL50 devant rentrer en vigueur en Europe en 2008. Proposal for a regulation of the
European parliament and of the council on classification, labelling and packaging of substances and
mixtures, and amending Directive 67/548/EEC and Regulation (EC) No 1907/2006.
Commission of the European Communities, Brussels, 27.6.2007 - COM(2007) 355 final , 2007/0121
(COD).Volume II (Annex I),
http://ec.europa.eu/enterprise/reach/ghs_legislation_en.htm (volume 2, annexe 1 )
Chromium
Chronic toxicity
DACTARI
Element
Symbol
Isotopes
51Cr
WHO
RN water guide value (Bq/L)
chemical water guide value (mg/L)
CMR classification
IARC (1 to 4)
0.05 (total Cr)
-
EPA
-
RfD (reference dose) mg/kg/d
NOAEL mg/kg/d
Risk phrases
Risk group (Delacroix)
Specific activities : 51Cr (1g = 3.42 1015 Bq)
IARC carcinogenicity to humans:
C:1
C : 2A
C : 2B
C:3
C:4
10000
CEE
Non carcinogen
Critical effect
Carcinogenic to humans
Probably carcinogenic to humans
Possibly carcinogenic to humans
Unclassifiable as to carcinogenicity for humans
Probably not carcinogenic for humans
Radiotoxic groups (Delacroix et al., 2002) :
G 1 : Exemption < 104 Bq
G 2 : Exemption < 105 Bq
G 3 : Exemption = 106 Bq
G 4 : Exemption = 107 Bq
G 5 : Exemption > 108 Bq
Chromium
Cr
Chemical compound
Chromium (VI) C : 1
Chromium (III) C : 3
Chromium (VI) C : 1-2
/
Chromium (VI) C : A(inh)
C : D(oral)
Chromium (III) C : D(oral)
Target organs :
Cr (III) liver, spleen
Cr(VI) liver, bone, kidneys
Chromium (VI) : 3 10-3
Chromium (III) : 1.5
Chromium (VI) K2CrO4 : 2.5
Chromium (III) Cr2O3 : 1468
Chromium (VI) CrO3 :
R49-R25
4