Iodine
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 inorganic compounds
Main organic compounds
Main industrial compounds (solution)
Biological role
Main isotopes
Iodine
I
53
126.9
Halogens
B. Courtois (1811)
Greek iodes meaning "violet"
[Kr] 4d10 5s2 5p5
4.94 g/cm3
113.7°C
184.3°C
Soft
2.66
2.20 Å
4-6
-I (I-), 0 (I2), I (IO-), V (IO3-), VII (IO65-)
+ 0.54 (I2/I-), +1.19 (IO3-/I2)
Caliche (calcium carbonate)
KI, AgI, NaI, CsI, CuI, ICN, IF7, IF5, PbI2, …
Thyroxine and triiodothyronine (thyroid hormones)
CH3I
Iodides (I-), Iodates (IO3-), Iodine (I2)
Present in thyroid hormones (thyroxine)
123I (T1/2 = 13.2 h, EC) medicine (1g = 7.14 1016 Bq)
125I (T1/2 = 59.4 d, EC, γ) medicine (1g = 6.42 1014 Bq)
129I (T1/2 = 1.6 107 y, β, ) (1g = 6.53 106 Bq)
131I (T1/2 = 8 d, β, γ) medicine (1g = 4.6 1015 Bq)
Iodine
Acute toxicity
DACTARI
Element
Symbol
Iodine (all soluble compounds)
Iodine
I
LD 50 (mg/kg) (rat/oral)
Classification LD50*
3.3 - 22 g/kg
NC
References
Fractional absorption : fA (ICRP 100)
Materno-fœtal transfer (ICRP 88)
INRS (FT 207), HSDB, WHO (2003)
1
3-4
*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 )
Iodine
Chronic toxicity
DACTARI
Element
Symbol
125I
WHO
RN water guide value (Bq/L)
chemical water guide value (mg/L)
CMR classification
IARC (1 to 4)
10
Isotopes
129I
1000
Iodine
I
Chemical compound
131I
10
Radioiodines shortlife C : 1
CH3I C : 3
CH3I C : 3
-
CEE
EPA
Non carcinogen
Critical effect
Target organs : Thyroid
RfD (reference dose) mg/kg/d
NOAEL mg/kg/d
0.01
Risk phrases
Risk group (Delacroix)
3
2
3
# Specific activities : 125I( 1g = 6.42 1014 Bq) – 129I (1g = 6.53 106 Bq) – 131I (1g = 4.6 1015 Bq)
IARC carcinogenicity to humans:
C:1
C : 2A
C : 2B
C:3
C:4
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