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Environmental fate & pathways

Monitoring data

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monitoring data
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The FOREGS study is a recent European reference for ambient metal concentrations in the environment covering the whole of the EU with the same methodology.

Data source

Reference Type:
study report

Materials and methods

Test guideline
no guideline followed
Principles of method if other than guideline:
Systematic study of the EU environment , sampled in a 70km x 70kmgrid, on locations, not specifically influenced by identified sources. as such, ambient metal levels are determined throughout the EU with a same methodology.
GLP compliance:
not specified
Type of measurement:
other: ambient background concnetration
surface water

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Test material form:
other: total In concentration measured
Details on test material:
freshwaters sampled all over the EU

Results and discussion

other: Europe
Substance or metabolite:
other: element
< 0.002 µg/L
Remarks on result:
other: 50P
Details on results:
Indium values in stream water range from <0.002 to 0.015 μg l-1, with a median value below the detection limit of 0.002 μg l-1. More than 90% of the data are less than the analytical limit of quantification, so only the highly anomalous values are clearly resolved, and proper interpretation of the results is impossible.
A few isolated enhanced indium values instream water occur in the Netherlands and in northern Germany on glaciofluvial terrains, in central and eastern Germany, and in Sicily (Italy).

Any other information on results incl. tables

In neutral aqueous solutions, indium forms a number of insoluble compounds, such as In(OH)3, In2S2, In(CO3)3 and InPO4. Indium in acid solutions may form several ionic species, e.g., InCl2+ and In(OH)2+, which are precipitated in the pH range of 5 to 9. Several organic anions, e.g., oxalate, are also capable of complexing indium. Compounds of trivalent indium are the most stable and only the trivalent ion is stable in aqueous solution. Compounds of lower oxidation states undergo oxidation in the presence of water to form In3+ and elemental indium. There are very few data on indium concentrations in natural water; in sea water the solubility appears to be controlled by In(OH)3 in equilibrium with In(OH)4-. In river water, indium is likely to occur in ultra-trace amounts, mainly in the form of small colloidal particles, which are efficiently removed in estuaries and coastal water by salt-induced flocculation and settling.

Applicant's summary and conclusion

Test carried out according to standard protocol, test results consistent, thus reliable for concluding on endpoint.
Executive summary:

The FOREGS study measured recent "ambient background" total Indium concentrations in streamwaters all over the EU. the 50P value observed was < 0.002 µg In/l.