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Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

This endpoint is covered by the category approach for soluble iron salts (please see the section for physical and chemical properties for the category justification/report format).

Environmental iron levels

Values for the Chemical Safety Assessment

The following table summarizes the levels considered as background concentrations in the present assessment. These background concentrations can be used in the environmental risk assessment.

Table: Environmental medium concentrations (upper level) of iron used for Chemical Safety Assessment (CSA)

Urban air Marine water Surface freshwater, dissolved Freshwater sediment Soil
[ng Fe/m³] Reference [µg Fe/L]  Reference [µg Fe/L]  Reference [g Fe/kg dw] Reference [g Fe/kg dw] Reference
 6000 WHO 2003  ca.5* OECD 2007  66 Gaillardet et al 2003  20 Vangheluwe et al 2010  20 Vangheluwe et al 2010

* calculated from ca. 10 µg/L, as hydroxide

It should be noted that some of the figures may deviate from those in table A3.1 of the SIAR (SIDS Initial Assessment Report, OECD 2007) document, which are given below. Nonetheless the above listed environmental levels are in comparable ranges.

Table: Summary of background concentrations & levels in biota from SIAR (OECD 2007, Table A3.1)

Matrix or organism

Typical concentration

(order of magnitude only)

Earth’s crust

5 %


Approx. 5 %*

Atmosphere – background

1 ng/m³

Atmosphere - urban

6000 ng/m³

Sediment – fresh water and marine

4.5 % d.w.*

River water – background

Approx. 1 mg/L (total)

Sea water – background

Approx. 10 µg/L, as hydroxide

Plants – roots

4000 mg/kg d.w.


200 mg/kg d.w.

Marine sediment organisms

Up to approx. 500 mg/kg d.w.

Marine algae

Up to approx. 500 mg/kg d.w.

Marine crustacean

Up to approx. 500 mg/kg d.w.


Up to approx. 500 mg/kg d.w.

Marine fish

5 – 30 mg/kg d.w.

Terrestrial animals

Typically up to 600 mg/kg d.w.

* Values deviate from those to be used in the chemical safety assessment given above

Natural occurrence of iron

Iron is the fourth most abundant element in the Earth's crust accounting for approximately 5 % by weight (Wildermuth 2004). Iron is found in various minerals (as ferric chloride, ferrous chloride, ferric sulphate, ferrous sulphate and their mixtures, oxides and sulphides) and in nearly all soils, sediments and mineral waters. Iron levels range from 0.01 mg/L in seawater up to 0.1 – 10 mg/L in fresh water, 0.5 – 5 % in soil and 1 – 9 % in sediments (Drever 1982, Hem 1970, Horne 1978, Kabata-Pendias & Pendias 1984, Khalid et al 1977, Lindsay 1979, Morel 1993, Stumm & Morgan 1981). Overall, the data show that iron is present naturally in abundance in all environmental compartments, apart from water, where solubility of the hydroxide and oxides is a limiting factor. The dissolved concentrations of iron tend to be low whereas sediment concentrations can be high.

Mobilization of natural iron from soils

Johnson et al (2007) summarize the mobilization of iron from soils with reference to Schnitzer (1969) as follows: “Hydrous iron(II) oxides [FeO(OH)] are generally red–brown gels and are the major constituents of soil. The major iron ores found in nature are haematite (Fe2O3), magnetite (Fe3O4), limonite [FeO(OH)] and siderite (FeCO3). Iron in crustal rocks is mobilized by weathering of iron silicates and carbonates. The weathering products are oxidized and hydrolyzed to insoluble ferric hydroxides and hydrous oxides that are then transported within the aquatic environment.”

  • Drever JI (1982). The geochemistry of natural waters; Prentice-Hall, Englewood Cliffs, NJ, U.S.A.
  • ECHA European Chemicals Agency (2008). Guidance on information requirements and chemical safety assessment Appendix R.7.13-2: Environmental risk assessment for metals and metal compounds. 74 p.
  • Gaillardet J, Viers J, Dupré B (2003). Trace elements in river waters. IN: Drever JI (Ed) Surface waters and Ground water, Weathering, and Soils, Treatise on Geochemistry. Vol 5 Elsevier ( Amsterdam), pp 225-272.
  • Hem JD (1970). Study and interpretation of the chemical characteristics of natural water, 2nd ed.
  • Horne RA (1978). The Chemistry of our Environment. John Wiley and Sons, New York, U.S.A.
  • Johnson I, Sorokin N, Atkinson C, Rule K, Hope S-J (2007). Proposed EQS for Water Framework Directive Annex VIII substances: iron (total dissolved). ISBN: 978-1-84432-660-0. Science Report: SC040038/SR9. SNIFFER Report: WFD52(ix). Product Code SCHO0407BLWB-E-E. Self-published by Environment Agency, Almondsbury, Bristol BS32 4UD, U.K. 65 p.
  • Kabata-Pendias A, Pendias H (1984). Trace elements in soils and plants; CRC Press, Boca Raton, FL, U.S.A.
  • Khalid RA, Gambrell RP, Verloo MG, Patrick WH (1977). Transformations of heavy metals and plant nutrients in dredged sediments as affected by oxidation reduction potential and pH; U.S. Army contract N DACW39-74-C-0076.
  • Lindsay WL (1979). Chemical equilibria in soils; John Wiley and Sons, New York, U.S.A.
  • Morel FMM (1983). Principles of aquatic chemistry; John Wiley and Sons, New York, U.S.A.
  • OECD Organisation for Economic Co-operation and Development (2007). SIDS Initial Assessment Report for SIAM 24. OECD, Paris, France, 17-20 April 2007. 138 p.
  • Schnitzer M (1969). Reactions between fulvic acid, a soil humic compound, and inorganic soil constituents. Soil Science Society of America Proceedings 33:75–81.
  • Stumm W, Morgan JJ (1981). Aquatic chemistry, 2nd ed.; John Wiley and Sons, New York, U.S.A.
  • Vangheluwe M, Vercaigne I, Vandenbroele M, Shtiza A, Heijerick D (2010). White Paper on exposure based waiving for iron and aluminium in soil and sediments. ARCHE, Stapelplein 70, Box 104, 9000 Gent, Belgium.
  • WHO World Health Organization (2003). Iron in Drinking-Water. Background document for development of WHO Guidelines for Drinking-water Quality. WHO, Geneva, 1996. 4 p. WHO/WSH/03.04/08.
  • Wildermuth E, et al (2004). Iron compounds. IN: Bohnet M et al (Eds). Ullman's Encyclopedia of Industrial Chemistry. 7th Edition. Wiley, New York, U.S.A. Web-version, Release 2004.